A Guide For Delineation Of Lymph Nodal Clinical Target Volume In Radiation Therapy

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A Guide For Delineation Of Lymph Nodal Clinical Target Volume In Radiation Therapy

  1. 1. Giampiero Ausili Cefaro ∙ Carlos A. Perez ∙ Domenico Genovesi Annamaria Vinciguerra (Eds.) A Guide for Delineation of Lymph Nodal Clinical Target Volume in Radiation Therapy
  2. 2. Giampiero Ausili Cefaro ∙ Carlos A. Perez Domenico Genovesi ∙ Annamaria Vinciguerra (Eds.) A Guide for Delineation of Lymph Nodal Clinical Target Volume in Radiation Therapy With 184 Figures and 12 Tables 123
  3. 3. Giampiero Ausili Cefaro, MD Domenico Genovesi, MD Department of Radiation Oncology Department of Radiation Oncology “G. d’Annunzio” University School University Hospital of Medicine Chieti Chieti Italy Italy Annamaria Vinciguerra, MD Carlos A. Perez, MD Department of Radiation Oncology Department of Radiation Oncology University Hospital Washington University Chieti St. Louis, MO Italy USA Translation from the Italian edition: “Guida per la contornazione dei linfonodi in radioterapia”. First edition: October 2006 © 2006 Il Pensiero Scientifico Editore All rights reserved in all countries ISBN 88-490-0173-8 ISBN 978-3-540-77043-5 e-ISBN 978-3-540-77044-2 DOI 10.1007/978-3-540-77044-2 Library of Congress Control Number: 2008927198 © 2008 Il Pensiero Scientifico Editore This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from the copyright holder. Violations are liable to prosecution under the German Copyright Law. The use of general descriptive names, registered names, trademarks, etc. in this publication does not im- ply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Product liability: the publishers cannot guarantee the accuracy of any information about dosage and application contained in this book. In every individual case the user must check such information by consulting the relevant literature. Cover design: Frido Steinen-Broo, eStudio Calamar, Spain Production & Typesetting: le-tex publishing services oHG, Leipzig, Germany Printed on acid-free paper 987654321 Springer.com
  4. 4. To our patients
  5. 5. Preface Image-guided 3D Conformal or Intensity Modu- by the various classification systems, which might lated Radiation Therapy aims to deliver high doses be hard to find in scans performed without contrast of radiation to the tumor, while trying to maintain medium. dose levels to healthy tissue within tolerable limits. Together with experienced radiologists for each Therefore, it is of key importance to define the dif- anatomical region, we have developed a set of stan- ferent target volumes, gross tumor volume (GTV), dards for the acquisition of planning CT images, clinical target volume (CTV), planning target vol- standardizing the parameters for scan performance ume (PTV), and organs at risk (OARs), on the basis and those concerning patient positioning and im- of in-depth knowledge of the human anatomy, of mobilization. anatomicoradiological aspects, and of anatomical In the second section of the book we describe the and geometric variations during the radiation plan- role and importance of radiological imaging in tar- ning and treatment. get definition, including lymph nodes, especially for We have prepared this guide to meet the needs image-guided radiation therapy (IGRT). of radiation oncologists: our intention is to pro- In the third section, radiologists and radiation vide them with guidelines for identifying and de- oncologists have identified and defined the lymph fining the lymph node structures to be included in nodes in the planning CT scans, concurrently iden- the treatment plan. Meeting this need also implies tifying and numbering anatomical landmarks. Con- responding to findings in the literature, which, as sultation of the CT images reproduced in this book, regards lymph node structures, reveal differences in starting from the head and neck region down to the contouring practices not only among different ra- pelvic region, is facilitated by a flipping page which diotherapy centers, but also, quite often, among ra- makes it possible to read the anatomicoradiological diation oncologists working in the same center. tables while viewing the scans. The book, after providing a brief anatomical de- While we are fully aware that our work is far scription of the human lymphatic system, reviews from having resolved all the issues of lymph nodal the main anatomical classifications which take into area identification, including taking into account the account lymph drainage pathways in the various variability of each patient’s physical shape, we hope it regions and describe the progression pathways of will prove to be a useful tool for young and, if we may the various types of cancer. We use well-established venture, also for not-so-young radiation oncologists classifications for the head and neck region and the and be an appropriate support in the delicate phase mediastinum, while we employ more recent or still of radiation treatment planning. evolving classifications for the abdominal and pelvic Giampiero Ausili Cefaro regions. We also provide reference tables that facili- Carlos A. Perez tate the identification of the lymph nodes described Domenico Genovesi Annamaria Vinciguerra
  6. 6. Contents Section I 1.4.4 Sacral or Presacral Lymph Nodes . . . 10 General Considerations . . . . . . . . . . . . . . . . . . . 1 1.4.5 Inguinal Lymph Nodes . . . . . . . . . . . . . 10 1 Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Lymph Node Classification . . . . . . . . . 11 1.1 Head and Neck Region . . . . . . . . . . . . . . 3 2.1 Head and Neck Region . . . . . . . . . . . . . 11 1.1.1 Occipital Lymph Nodes . . . . . . . . . . . . . 3 2.2 Mediastinal Region . . . . . . . . . . . . . . . . 13 1.1.2 Mastoid or Retroauricular 2.3 Upper Abdominal Region . . . . . . . . . . 20 Lymph Nodes . . . . . . . . . . . . . . . . . . . . . . 3 2.4 Pelvic Region . . . . . . . . . . . . . . . . . . . . . . 26 1.1.3 Parotid Lymph Nodes . . . . . . . . . . . . . . . 4 1.1.4 Submandibular Lymph Nodes . . . . . . . 4 3 Anatomicoradiological 1.1.5 Submental Lymph Nodes . . . . . . . . . . . . 4 Boundaries . . . . . . . . . . . . . . . . . . . . . . . 29 1.1.6 Facial Lymph Nodes . . . . . . . . . . . . . . . . 5 3.1 Head and Neck Region . . . . . . . . . . . . . 29 1.1.7 Sublingual Lymph Nodes . . . . . . . . . . . . 5 3.2 Mediastinal Region . . . . . . . . . . . . . . . . 30 1.1.8 Retropharyngeal Lymph Nodes . . . . . . 5 3.3 Upper Abdominal Region . . . . . . . . . . 34 1.1.9 Anterior Cervical Lymph Nodes . . . . . 5 3.4 Pelvic Region . . . . . . . . . . . . . . . . . . . . . . 34 1.1.10 Lateral Cervical Lymph Nodes . . . . . . . 5 1.2 Thoracic Region . . . . . . . . . . . . . . . . . . . . 6 4 Planing CT: Technical Notes . . . . . . . . 39 1.2.1 Parietal Lymph Nodes . . . . . . . . . . . . . . . 6 1.2.2 Visceral Lymph Nodes . . . . . . . . . . . . . . 7 1.3 Upper Abdominal Region . . . . . . . . . . . 7 Section II 1.3.1 Abdominal Visceral Lymph Nodes . . . 8 Target Volume Delineation 1.3.2 Lumboaortic Lymph Nodes . . . . . . . . . . 8 in Modern Radiation Therapy . . . . . . . . . . . . 43 1.4 Pelvic Region . . . . . . . . . . . . . . . . . . . . . . . 8 1.4.1 Group of the Common Iliac Lymph 5 Critical Importance of Target Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Definition, Including Lymph Nodes, 1.4.2 Group of the Internal Iliac Lymph in Image-Guided Radiation Therapy 45 Nodes (or Hypogastric) . . . . . . . . . . . . . 9 5.1 Target Volume and Critical Structure 1.4.3 Group of the External Iliac Lymph Delineation . . . . . . . . . . . . . . . . . . . . . . . 47 Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5.2 Delineation of Lymph Node Volumes 53
  7. 7. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy 5.3 Implications of Target Definition 7 Mediastinal Lymph Nodes ........ 97 for Innovative Technology in Contemporary Radiation Therapy . . . 56 8 Upper Abdominal Region 5.4 Quality Assurance . . . . . . . . . . . . . . . . . 56 Lymph Nodes . . . . . . . . . . . . . . . . . . . . 113 5.5 Cost Benefit and Utility . . . . . . . . . . . . 57 5.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . 59 9 Pelvic Lymph Nodes . . . . . . . . . . . . . . 137 10 Digitally Reconstructed Section III Radiographs (DRRs) . . . . . . . . . . . . . . 161 Axial CT Radiological Anatomy . . . . . . . . . 61 6 Head and Neck Lymph Nodes . . . . . 63 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 X
  8. 8. Contributors Antonietta Augurio, MD Antonella Filippone, MD Department of Radiation Oncology Department of Radiology University Hospital University Hospital Chieti Chieti Italy Italy Nicola Filippo Basilico, MD James A. Purdy, PhD Department of Radiation Oncology Department of Radiation Oncology University Hospital University of California, Davis Medical Center Chieti Sacramento, CA Italy USA Raffaella Basilico, MD Pietro Sanpaolo, MD Department of Radiology Department of Radiation Oncology University Hospital Regional Oncological Hospital, CROB Chieti Rionero in Vulture Italy Italy Marco D’Alessandro, MD Maria Luigia Storto, MD Department of Radiation Oncology Director of Radiology Department University Hospital “G. d’Annunzio” University School of Medicine Chieti Chieti Italy Italy Angelo Di Pilla, MD Maria Taraborrelli, MD Department of Radiation Oncology Department of Radiation Oncology University Hospital University Hospital Chieti Chieti Italy Italy
  9. 9. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy Armando Tartaro Lucia Anna Ursini, MD Professor of Radiology Department of Radiation Oncology “G. d’Annunzio” University School of Medicine University Hospital Chieti Chieti Italy Italy XII
  10. 10. S ec t io n I General Considerations
  11. 11. Anatomy 1 1.1 Head and Neck Region • Anterior and lateral cervical lymph nodes of the neck, located anterior and lateral to the neck, The head and neck region [1, 2] has a dense lym- respectively phatic network which, through the jugular, spinal accessory, and transverse cervical nodes under the 1.1.1 Occipital Lymph Nodes jugular-subclavian axis, drains lymph from the skull base to the thoracic duct. They are adjacent to the occipital artery. Rouvière Lymph drainage of the anatomical structures distinguishes them into superficial, subfascial, and belonging to this region is ipsilateral, apart from submuscular. tonsil, soft palate, basal tongue, posterior pharyn- The superficial nodes are located at the level of geal wall, and, especially, nasopharynx, all of which the insertion of the sternocleidomastoid and the drain bilaterally. Vocal folds, paranasal sinuses, and trapezius muscles; the subfascial nodes are situated middle ear do not have lymph vessels, or have them above the splenius muscle; and the submuscular in limited number. nodes are located below the splenius muscle. According to Rouvière, head and neck lymph They receive lymphatics from the occipital area nodes are clustered in groups or form chains that of the scalp and from the skin and deep regions of are satellites of the main blood vessels (Fig. 1.1). the upper nape. These nodal groups are listed below: • The pericervical ring, which includes six nodal 1.1.2 Mastoid or Retroauricular groups surrounding the upper neck: Lymph Nodes – Occipital nodes – Mastoid or retroauricular nodes They are located on the superficial aspect of the an- – Parotid nodes terior and superior insertions of the sternocleido- – Submandibular nodes mastoid muscle. – Submental nodes They receive lymphatics from the skin of the me- – Facial nodes dial aspect of the ear, the back of the temporal re- • Sublingual and retropharyngeal lymph nodes, gion, and the parietal area of the skull. located medial to the pericervical nodal ring 3
  12. 12. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy Fig. 1.1 a,b Main head and neck nodes. a Lateral view. b Anteroposterior view 1.1.3 Parotid Lymph Nodes 1.1.4 Submandibular Lymph Nodes They are divided into: These are deep nodes, anatomically located in the • Superficial nodes. They are located in front of submandibular cavity, adjacent to the salivary gland the tragus, along the superficial temporal vessels. and the anterior facial vein. Rouvière divided them • Extraglandular subfascial nodes. They are lo- into five groups: periglandular, perivascular, retro- cated in the parotid cavity immediately below the vascular, retroglandular, and intracapsular. fascia. They receive lymph collectors from the lower lip, • Deep intraglandular nodes. They are scattered lateral chin, cheek, gums, teeth, internal eyelids, within the parotid gland, close to the external anterior tongue, submandibular gland, sublingual jugular vein and the facial nerve. gland, and floor of mouth. They receive lymphatics from the parotid, the frontal 1.1.5 Submental Lymph Nodes and temporal regions, lacrimal gland, upper eyelid, lateral half of the lower eyelid, tympanic membrane, They are located superficially at the level of the Eustachian tube, auricle, external auditory meatus, suprahyoid region, on the lower aspect of the my- nose, upper lip, cheek, and gums in the molar area. lohyoid muscle. 4
  13. 13. Anatomy 1 They drain the chin, lower lip, cheeks, gums, low- 1.1.10 Lateral Cervical Lymph Nodes er incisors, floor of mouth, and tip of tongue. They are divided into: 1.1.6 Facial Lymph Nodes • Superficial (external jugular chain). They follow the external jugular vein. They are located along the course of the facial lymph • Deep. They are located in the carotid region and vessels, which follow the facial artery and vein; they the supraclavicular cavity. They extend posterior- include the buccinator, mandibular, infraorbital, ly under the trapezius muscle, while downward and zygomatic nodes which receive lymphatics and forward they reach below the clavicle to the from adjacent areas. anterior chest. According to Rouvière’s classifica- tion three chains are distinguished: 1.1.7 Sublingual Lymph Nodes 1. Internal jugular chain, satellite of the vein: it includes an anterior and a lateral group. The These are inconstant and are located along the anterior lymph nodes run anterior to the jugu- course of the collector vessels of the tongue. lar vein, while the lateral ones follow the lateral wall of the vein, extending from the posterior 1.1.8 Retropharyngeal Lymph Nodes belly of the digastric muscle to the crossing of the omohyoid muscle passing behind the They are distinguished into medial, located along vein in the lower portion. The internal jugular the lymphatics of the posterior aspect of the phar- chain drains the anterior portion of the head ynx, above the hyoid bone, and lateral, at the level and neck, nasal cavity, pharynx, ear, tongue, of the lateral masses of the atlas, in contact with the palate, salivary glands, tonsils, and thyroid. lateral margin of the posterior pharyngeal wall. 2. Spinal accessory nerve chain: it follows the They receive lymph from the nasal cavity, para- lateral branch of the nerve in the posterior tri- nasal sinuses, palate, middle ear, nasopharynx, and angle of the neck. It runs under the trapezius oropharynx. muscle, starting from the posterior margin of the sternocleidomastoid muscle to the upper 1.1.9 Anterior Cervical Lymph Nodes margin of the supraspinous fossa. It receives lymph from the occipital, postauricular, and They are located below the hyoid bone, between the suprascapular nodes and from the posterior two vascular-nervous bundles of the neck. They are and lateral nape, lateral neck, and shoulder. divided into two groups: 3. Transverse chain of the neck (supraclavicu- 1. Anterior jugular chain. It is located below the lar): it follows the transverse artery. It is lo- superficial cervical fascia along the course of the cated transversally, from the lower margin of anterior jugular vein. the spinal accessory chain to the junction of 2. Juxtavisceral lymph nodes. They are located the internal jugular and subclavian veins. It re- frontal to the larynx (prelaryngeal), the thyroid ceives lymph from the accessory spinal chain, (prethyroid), and the trachea (pretracheal), and the breast region, the anterior and lateral neck, on the lateral aspects of the trachea (recurrent and the upper limb. chains). They drain larynx, thyroid, trachea, and esophagus. 5
  14. 14. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy 1.2 Thoracic Region heads of the ribs; they are also called paraverte- bral nodes. They drain lymphatic vessels from the Thoracic lymph nodes [3] are divided into parietal thoracic wall, which receive lymph from the pari- and visceral. etal pleura and from the lymphatic vessels of the spinal cord and paravertebral grooves. 1.2.1 Parietal Lymph Nodes • Diaphragmatic lymph nodes. Located in the diaphragmatic convexity, they are grouped in • Internal thoracic lymph nodes. They form two the loose cellular tissue at the base of the peri- chains, on either side of the posterior aspect of the cardium. They are divided into an anterior group, sternum, from the xiphoid process to the first rib, behind the xiphoid process; a right lateral group along the course of the internal thoracic vessels. at the level of the diaphragmatic orifice of the They receive lymph collectors from the skin of inferior vena cava; a left lateral group, near the the anterior thoracic wall, the anterior intercostal phrenic nerve; and a posterior group behind the spaces, the epigastric area, the medial breast, and diaphragmatic crura. They receive lymphatic ves- the anterior diaphragmatic lymph nodes. sels from the diaphragm. • Intercostal lymph nodes. They are located in the posterior portion of intercostal spaces, near the Fig. 1.2 a,b Main visceral mediastinal nodes. a Superficial view. b Deep view 6
  15. 15. Anatomy 1 1.2.2 Visceral Lymph Nodes vessels from the lungs and heart. They are divid- ed into: Rouvière divided the visceral lymph nodes of the – Lymph nodes of the pulmonary pedicle, lo- chest into four groups (Fig. 1.2): cated between the origin of the bronchus and 1. Anterior mediastinal or prevascular nodes. the mediastinal pleural reflection They run between the sternum and the heart, an- – Subcarinal nodes, situated below the carina terior to the great vessels. They receive lymphat- – Peritracheal nodes, located on the anterior ics from the thymus, heart, and trachea. and lateral aspects of the trachea and a few 2. Posterior mediastinal or juxtaesophageal posteriorly nodes. They are located between the posterior 4. Intrapulmonary lymph nodes. They follow the aspect of the pericardium and the vertebral col- bronchial divisions in the lungs. umn: they are divided into pre- and retroesopha- geal nodes. They drain the lateral and posterior 1.3 Upper Abdominal Region lymph nodes and the esophagus. 3. Peritracheobronchial lymph nodes. They are Abdominal lymph nodes [1, 3, 4] can be divided into very numerous and are located around the tra- two main groups: visceral nodes and lumboaortic chea and main bronchi. They receive lymphatic nodes (Fig. 1.3). Fig. 1.3 a,b Main abdominal lymph nodes. a Perigastric region. b Lymph nodes along principal abdominal vessels 7
  16. 16. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy 1.3.1 Abdominal Visceral Lymph Nodes • Postaortic group. These nodes are located poste- rior to the aorta and anterior to the third-fourth Important lymph node chains are grouped along the lumbar vertebrae. lymphatic pathways from the abdominal organs: • Coronary chain (left gastric lymph nodes). It 1.4 Pelvic Region runs along the lesser gastric curvature and the left gastric artery. Lymphatic drainage of the pelvis [1, 3, 4] is common- • Gastroepiploic chain (right gastric lymph nodes) ly divided into two chains: parietal and visceral. The along the greater gastric curvature. parietal lymphatics include the lymphatic vessels of • Splenic or lienal chain (pancreaticolienal chain) the skin and the superficial fascia of the anterior and along the upper pancreas and at the hilum of posterior pelvic walls. The visceral lymphatic chains spleen. include the lymphatic vessels draining the urogeni- • Hepatic chain (hepatic lymph nodes). It runs tal region, the rectum, and the peritoneum. along the hepatic artery and the retropancreatic In addition to the lymph nodes situated in common bile duct. strictly visceral locations, the pelvic visceral lymph • Superior and inferior mesenteric chains. They nodes also comprise the following groups of nodes run between the mesenteric layers. The lymph (Fig. 1.4) [5]. nodes of these chains are especially numerous at the level of the jejunum where they run along the 1.4.1 Group of the Common course of the branches of the mesenteric artery Iliac Lymph Nodes and the root of the mesentery. It consists of three nodal chains: 1.3.2 Lumboaortic Lymph Nodes 1. Lateral 2. Intermediate They can be divided into eight subgroups according 3. Medial to their position with respect to the aorta and the vena cava. Below, we list the subgroups of the nodes The lateral chain is an extension of the lateral chain located around the aorta. of external iliac nodes and is located lateral to the • Lateroaortic group (bilateral). The right lat- common iliac artery. The intermediate chain con- eroaortic subgroup can be further divided into: sists of the nodes of the lumbosacral fossa, which aortocaval, lateral caval, precaval, and postcaval is delimited anteriorly by the common iliac vessels, subgroups, all adjacent to the vena cava. Lat- laterally by the psoas muscle, medially by the lum- eroaortic lymph nodes receive afferents from the bosacral vertebrae and posteriorly/inferiorly by the common iliac lymph nodes and the lumbar, sper- ala of sacrum. The lymph nodes can be located be- matic, and utero-ovarian lymphatics. tween the common iliac artery and veins. The me- • Preaortic group. These nodes are located ante- dial chain is located in the triangular area formed rior to the aorta, immediately below the origin of by the two common iliac arteries, from the aortic the superior and inferior mesenteric arteries, and bifurcation to the bifurcation of the internal and ex- they receive afferent lymphatics from the rectum, ternal iliac arteries. The lymph nodes of the sacral colon, small intestine, pancreas, stomach, liver, promontory are included in this chain. and spleen. The common iliac lymph nodes receive afferents 8
  17. 17. Anatomy 1 other. However, we can distinguish two different nod- al chains: the anterior nodes, located anterior to the hypogastric vessels near the origin of the umbilical and obturator arteries, and the lateral sacral nodes, located along the course of the lateral sacral arteries, anterior to the first and second sacral foramen. The internal iliac nodes receive the gluteal and ischial lymphatics, the obturator lymphatics, and the visceral pelvic lymphatics (coming from rectum, bladder, prostate, seminal vesicles, deferent ducts, uterus, and vagina). 1.4.3 Group of the External Iliac Lymph Nodes This group includes the lymph nodes located around the external iliac vessels, and includes three nodal chains: 1. Lateral 2. Intermediate 3. Medial Fig. 1.4 Main pelvic lymph nodes The lateral chain includes the nodes located lateral to the external iliac artery and medial to the psoas muscle. The intermediate chain includes the nodes located between the external iliac artery and veins. from the internal and external iliac nodes, presacral The medial chain includes the nodes located me- nodes, and some lymphatics coming directly from dial and posterior to the external iliac vein. pelvic viscera. The lymphatics of the common iliac There are controversies concerning the denomi- nodes ascend toward the para-aortic nodes. nation of the medial chain nodes, which are also known as obturator lymph nodes. These nodes are 1.4.2 Group of the Internal Iliac Lymph adjacent to the obturator vessels and, according to Nodes (or Hypogastric) some authors, should not belong to the external iliac nodes, but rather to the internal iliac nodes. Howev- The internal iliac nodes include several nodal chains er, other authors [6] consider medial chain nodes as which run along the various visceral branches of the being functionally linked to the external iliac chain internal iliac artery, such as the uterine artery, the and located in an area delimited superiorly by the prostatic branches of the inferior and middle rectal external iliac vein, posteriorly by the internal iliac arteries, the superior and inferior gluteal arteries, artery followed by the pelvic ureter, and inferiorly and the internal pudendal artery. These nodes are by the obturator nerve. In surgical terminology they difficult to distinguish since they are adjacent to each are referred to as obturator lymph nodes, but should 9
  18. 18. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy not be confused with the small, isolated obturator 3. Lower lateral group lymph node located in the internal foramen of the 4. Lower medial group obturator canal, in the lower portion of the hom- onymous fossa. This single lymph node is function- The lower medial and lower lateral nodes drain the ally linked to the internal iliac chain throughout its superficial lymphatics from the lower limb. The efferent vessels. upper lateral nodes receive superficial lymphatics The external iliac nodes receive inguinal lym- from the lateral gluteal region and from the lateral phatics, deep lymphatics from the anterior and sub- and posterior subumbilical region of the abdomi- umbilical portion of the abdominal wall, circumflex nal wall. The upper medial nodes drain the exter- iliac lymphatics, and part of the genitourinary lym- nal genitalia, the anus, the superficial perineum, the phatics. medial gluteal region, and the anterior subumbilical abdominal wall. 1.4.4 Sacral or Presacral Lymph Nodes The deep inguinal nodes run along the common femoral vessels, within the femoral canal, medial to They are located in the anterior aspect of sacrum, the femoral vein, and drain into the medial chain on either side of the rectum. They drain lymphatics of external iliac nodes. They are separated from the from the rectum and the pelvic wall. group of superficial inguinal nodes by fascial planes which are not clearly visible on computed tomogra- 1.4.5 Inguinal Lymph Nodes phy (CT) images. The inguinal ligament at the ori- gin of inferior epigastric vessels and circumflex iliac The lymph nodes of the inguinofemoral region can vessels is used as a landmark for distinguishing the be divided into superficial and deep nodes. deep inguinal nodes from the medial chain of the The superficial inguinal nodes are located in external iliac nodes. the subcutaneous tissue anterior to the inguinal The deep inguinal nodes drain lymphatics from ligament and run along the course of the superficial the superficial inguinal lymph nodes, the glans, (distal) femoral vein and saphenous vein. They can the clitoris, and some deep lymphatics of the lower be further subdivided into four areas indicated by limb. two imaginary, vertical and horizontal lines cross- ing at the level of the saphenofemoral junction: 1. Upper lateral group 2. Upper medial group 10
  19. 19. Lymph Node Classification 2 The presence in our body of a rich network of • Pelvic region, we referred to the distribution of lymph vessels and numerous lymph node stations lymph node groups relative to the main arteries. prompted several authors to draw up classifications that would take into account lymph drainage path- 2.1 Head and Neck Region ways in the various districts and would be useful for describing tumor progression pathways. For nearly four decades, the most commonly used The lymph node classifications of different ana- classification of cervical lymph nodes was that de- tomical regions, mostly prepared by surgeons, have veloped by Rouvière [2] in 1938, based on a previous provided valuable help for the execution and stan- classification by Trotter (1930) [9] which was based dardization of surgical procedures, offering an ef- on an earlier study by Poirer and Charpy in 1909 fective tool for ensuring their reproducibility. [10]. This classification defined lymph node areas With the development of new radiotherapy tech- based on anatomical limits established through pal- niques, especially conformal radiotherapy, radia- pation or surgical dissection. tion oncologists have also started using these clas- In subsequent years, the need was felt for a clas- sifications to define the nodal clinical target volume sification based on new clinical and pathophysi- (CTV) [7, 8] that appears to be increasingly selec- ological considerations, specifically, in relation to tive. surgical neck dissection techniques; consequently, We have considered the following classifications several new classification systems were proposed for lymph node contouring on CT: [11–14]. • Head and neck region, classification of the In 1991 the AAO-HNS classified neck lymph American Head and Neck Society/American nodes into levels, following a system originally Academy of Otolaryngology Head and Neck Sur- proposed by the Memorial Sloan-Kettering Can- gery (AHNS/AAO-HNS, 1998, Robbins classifi- cer Group (New York) [15]. This classification, also cation). known as the Robbins classification [16], distin- • Mediastinal region, American Joint Committee guishes six levels: on Cancer/International Union Against Cancer • IA, submental lymph nodes (AJCC/UICC) classification, 1996 (Mountain • IB, submandibular lymph nodes and Dresler). • II, upper jugular lymph nodes • Upper abdominal region, classification of the • III, middle jugular lymph nodes Japanese Gastric Cancer Association (JGCA). • IV, lower jugular lymph nodes 11
  20. 20. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy • V, posterior triangle lymph nodes whose members also included the radiologist Peter • VI, anterior compartment lymph nodes M. Som, who was tasked with defining the radio- logical margins of the various levels. The commit- It considers the lymph nodes that are removed dur- tee decided to continue using the six-level system ing neck dissections. The lymph nodes that are not (thus excluding the introduction of a level VII for commonly removed, such as retropharyngeal, pa- upper mediastinal lymph nodes) and to indicate rotid, buccal, and occipital nodes, are not included the lymph nodes through their anatomical sites in the Robbins classification. Subsequently, this clas- (e. g., retropharyngeal, parotid, buccal, retroau- sification was recommended by the UICC [17]. ricular, and suboccipital nodes). The main changes In 1992, in the TNM classification of malignant concerned the revision of the classification of neck tumors, the division of the head and neck lymph dissections, and the proposal of a further subdivi- nodes into 12 groups was proposed, based on the sion of levels II and V into IIA–IIB, separated by descriptions made by Rouvière [18]: the spinal accessory nerve, and VA–VB, divided by 1. Submental nodes a plane defined by the inferior margin of the cricoid 2. Submandibular nodes cartilage [20–23]. 3. Upper jugular lymph nodes Each of these sublevels defines a site with a dif- 4. Middle jugular lymph nodes ferent clinical implication in the event of metastatic 5. Lower jugular lymph nodes involvement. For instance, level II subclassifica- 6. Dorsal cervical nodes along the spinal acces- tion is justified by the fact that level IIB is mostly sory nerve involved in oropharyngeal and nasopharyngeal tu- 7. Supraclavicular nodes mors, while it is less often involved in neoplasms 8. Prelaryngeal and paratracheal nodes of the oral cavity, larynx, and hypopharynx. Thus, 9. Retropharyngeal nodes when tumors occur in the latter sites, without clini- 10. Parotid nodes cal involvement of sublevel IIA, it is not necessary 11. Buccal nodes to include level IIB in the dissection [20–23]. This 12. Retroauricular and occipital nodes is especially important if we consider the possible dysfunctions of the trapezius muscle due to ma- In 1997, the fifth edition of the cancer staging hand- nipulation of the spinal accessory nerve performed book of the AJCC [19], introduced, in addition to for removing level IIB nodes. Similar surgical con- the Robbins classification, a further level including siderations apply to level IA which is removed only the lymph nodes below the suprasternal notch. Al- in the presence of neoplasms of the floor of mouth, though they are not located in the neck but in the lips, anterior mobile tongue, or anterior alveolar upper mediastinum, lymph nodes belonging to this mandibular arch. The subclassification into VA and level can be involved in head and neck cancer (e. g., VB is warranted by the fact that neoplasms that are subglottic, hypopharyngeal, and thyroid tumors). the main cause of metastatic lymph nodes in those In 1998, 10 years after the start of the classifica- sites originate from the nasopharynx, the orophar- tion project, the AHNS in collaboration with the ynx, and skin structures of the posterior scalp for AAO-HNS, updated the original classification sys- level VA, and from the thyroid for level VB (Fig. 2.1; tem of 1991 to account for the changes in head and Table 2.1). neck cancer staging introduced by the AJCC [19]. Recently a group of authors [24] has proposed a K. Thomas Robbins headed the AHNS committee, further division of level VA into two sections, VAs 12
  21. 21. Lymph Node Classification 2 Fig. 2.1 Graphic representation of the six levels of lymph nodes accord- ing to the Robbins classification. Adapted from Robbins KT, Atkinson JLD, Byers RM, et al. (2001) [23] (superior) and VAi (inferior), separated by a hori- apex of level V are not necessary and should only zontal plane defined by the upper margin of the be considered in some skin cancers of the posterior body of the hyoid bone, at the level of the lower two scalp and neck. thirds of the spinal accessory nerve. The distinction The same authors also introduced the division, between the posterior edge of sublevel IIB and the considered by Robbins [20], of level IV into IVA apex of sublevel VA is not clear, and is virtually im- (lymph nodes located deep into the sternal head possible during most neck dissections. Indeed, for of the sternocleidomastoid muscle) and IVB (deep complete sublevel IIB removal, even the most ex- into the clavicular head of the sternocleidomastoid perienced surgeons usually also remove the upper muscle). In the past, Byers et al. [27] had also de- portion of sublevel VA. Already in 1987, Suen and fined a level IIIB including lymph nodes situated far Goepfert [25] had proposed inclusion of the apex of posterior to the internal jugular vein. the portion that would be later defined sublevel VA, in sublevel IIB, thus considering that the upper edge 2.2 Mediastinal Region of level V is adjacent to the lower part of the spinal accessory nerve. Similar to the head and neck region, for the medi- Moreover, the upper part of sublevel VA only astinal region there are different classification sys- contains the superficial suprafascial occipital lymph tems which have been updated over the years. nodes and, in smaller number, the subfascial and In 1967, Rouvière [3] classified pulmonary lymph submuscular lymph nodes located close to the oc- nodes dividing them into four groups: cipital insertion of the sternocleidomastoid muscle. 1. Anterior mediastinal group These lymph nodes receive lymph drainage from the 2. Posterior mediastinal group skin of the mastoid and occipital regions and are not 3. Peritracheobronchial group usually involved in head and neck tumors, except in 4. Intrapulmonary group cases of skin cancer. In most head and neck carcino- mas, dissection and/or radiation therapy [26] of the 13
  22. 22. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy Table 2.1 – Robbins classification Level Name Description Regions drained IA Submental Lymph nodes within the triangular boundary of the anterior belly of the Floor of mouth, anterior nodes digastric muscles and the hyoid bone oral tongue, anterior mandibular alveolar ridge, and lower lip IB Submandibular Lymph nodes within the boundaries of the anterior and posterior bellies Oral cavity, anterior nasal nodes of the digastric muscle, the stylohyoid muscle, and the mandibular body. cavity, and soft tissue It includes the pre- and postglandular nodes and the pre- and postvascu- structures of the mid- lar nodes. The submandibular gland is included in the specimen when the face, and submandibular lymph nodes within this triangle are removed gland IIA–IIB Upper jugular Lymph nodes located around the upper third of the internal jugular vein Oral cavity, nasal cavity, nodes and adjacent to spinal accessory nerve extending from the level of the nasopharynx, orophar- skull base to the level of the inferior border of the hyoid bone. The anterior ynx, hypopharynx, (medial) boundary is the lateral border of the sternohyoid muscle and the larynx, and parotid gland stylohyoid muscle, and the posterior (lateral) boundary is the posterior border of the sternocleidomastoid muscle IIA lymph nodes: Lymph nodes located anterior (medial) to the vertical plane defined by the spinal accessory nerve IIB lymph nodes: Lymph nodes located posterior (lateral) to the vertical plane defined by the spinal accessory nerve III Middle jugular Lymph nodes located around the middle third of the internal jugular vein Oral cavity, nasopharynx, nodes extending from the inferior border of the hyoid bone to the inferior border oropharynx, hypophar- of the cricoid bone. The anterior (medial) boundary is the lateral border of ynx, and larynx the sternohyoid muscle, and the posterior (lateral) boundary is the poste- rior border of the sternocleidomastoid muscle or the sensory branches of the cervical plexus IV Lower jugular Lymph nodes located around the lower third of the internal jugular vein Hypopharynx, cervical nodes extending from the inferior border of the cricoid bone to the clavicle. The esophagus, and larynx anterior (medial) boundary is the lateral border of the sternohyoid muscle and the posterior (lateral) boundary is the posterior border of the sterno- cleidomastoid muscle or the sensory branches of the cervical plexus VA–VB Posterior triangle This group is comprised predominantly of the lymph nodes located along Nasopharynx and nodes the lower half of the spinal accessory nerve and the transverse cervical oropharynx artery. The supraclavicular nodes are also included in this group. The superior boundary is formed by convergence of the sternocleidomastoid and trapezius muscles, the inferior boundary is the clavicle, the anterior (medial) boundary is the posterior border of the sternocleidomastoid muscle or the sensory branches of the cervical plexus, and the posterior (lateral) boundary is the anterior border of the trapezius muscle VA lymph nodes: Lymph nodes located above the horizontal plane defined by the inferior border of the cricoid cartilage. Included are the lymph nodes lying along the spinal accessory nerve VB lymph nodes: Lymph nodes located below the horizontal plane de- fined by the inferior border of the cricoid cartilage. In- cluded are the lymph nodes lying along the transverse cervical artery and the supraclavicular nodes, except the Virchow node which is located in level IV VI Anterior com- Lymph nodes in this compartment include the pre- and paratracheal Thyroid gland, glottic partment nodes nodes, precricoid (Delphian) node, and the perithyroidal nodes includ- and subglottic larynx, ing the lymph nodes along the recurrent laryngeal nerves. The superior apex of the piriform boundary is the hyoid bone, the inferior boundary is the suprasternal sinus, and cervical notch, and the lateral boundaries are the common carotid arteries esophagus Source: Adapted from Robbins KT, Clayman G, Levine PA, et al. (2002) [22] 14
  23. 23. Lymph Node Classification 2 Subsequently, two main classifications were pro- for its limited acceptance was the lack of an English posed: the classification of the AJCC adapted from translation until March 2000 [37]. Naruke [28–31] and that of the American Thoracic The AJCC produced a classification of 13 lymph Society (ATS) and the Lung Cancer Study Group node stations [38], however, it did not provide a de- (LCSG) [32–36]. scription of the anatomical boundaries of each sta- In 1978, Naruke suggested the use of an anatomi- tion: cal “map” in which the lymph node stations were • N2 nodes (within the mediastinum) numbered [29] and provided an anatomical defini- – Superior mediastinal nodes tion of 14 lymph node stations: 1. Highest mediastinal nodes 1. Superior mediastinal lymph nodes, located at 2. Upper paratracheal nodes the upper third of the trachea within the tho- 3. Pretracheal and retrotracheal nodes rax 4. Lower paratracheal nodes (including azy- 2. Paratracheal lymph nodes, corresponding to gos nodes) a level between stations 1 and 4, and situated – Aortic nodes along the lateral sides of the trachea 5. Subaortic (aortic window) 3. Pretracheal, retrotracheal, or posterior medi- 6. Para-aortic nodes (ascending aorta or phre- astinal, and anterior mediastinal lymph nodes nic) 4. Tracheobronchial nodes, in the lateral portion of – Inferior mediastinal nodes the junction between the trachea and the main 7. Subcarinal nodes bronchi (on the right side they are located at the 8. Paraesophageal nodes (below the carina) level of the azygos vein and on the left side they 9. Pulmonary ligament nodes are adjacent to the subaortic lymph nodes) • N1 nodes (nodes lying distal to the mediastinal 5. Subaortic lymph nodes pleural reflection) 6. Para-aortic lymph nodes 10. Hilar nodes 7. Subcarinal lymph nodes 11. Interlobar nodes 8. Paraesophageal nodes (below carina) 12. Lobar nodes 9. Pulmonary ligament lymph nodes 13. Segmental nodes 10. Hilar lymph nodes 11. Interlobar lymph nodes (the right interlobar In 1983 the ATS created a Committee on Lung nodes are classified, if necessary, into superior Cancer in order to draw up a “map” of regional and inferior) lymph nodes meeting the requirements of all 12. Lobar lymph nodes medical specialties concerned with lung cancer 13. Segmental lymph nodes [32]. The guidelines for the development of the clas- 14. Subsegmental lymph nodes sification were: avoid using the terms “mediastinal” and “hilar” since they are not specific from the The Japan Lung Cancer Society adopted this map- anatomicoclinical viewpoint; use the relationships ping and published a handbook for the classifica- with the main anatomical structures identifiable tion of lung cancer, providing detailed descriptions by mediastinoscopy (hence, on the right side: in- based on CT imaging and surgical findings, for each nominate artery, trachea, azygos vein, right main of the stations defined by Naruke. Although this bronchus, origin of the right superior lobe bronchus, manual has been widely used in Japan, it has not carina; on the left side: aorta, left pulmonary artery, been universally accepted. One of the main reasons ligamentum arteriosum, left main bronchus); and 15
  24. 24. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy favor the margins that can be visualized on a stan- 8. Paraesophageal nodes. Nodes dorsal to the dard chest X-ray or CT scan. posterior wall of the trachea and to the right The following definitions of regional lymph node or left of the esophageal midline. Retrotrache- stations for prethoracotomy staging were proposed: al but not subcarinal nodes are included. X. Supraclavicular nodes. 9. Right or left pulmonary ligament nodes. 2R. Right upper paratracheal (suprainnominate) Nodes within the right or left pulmonary liga- nodes. Nodes to the right of the midline of the ment. trachea between the intersection of the caudal 10R. Right tracheobronchial nodes. Nodes to the margin of the innominate artery with the tra- right of the tracheal midline from the level of chea and the apex of the lung. Highest right the cephalic margin of the azygos vein to the mediastinal nodes are included in this station. origin of the right superior lobe bronchus. 2L. Left upper paratracheal (supra-aortic) nodes. 10L. Left peribronchial nodes. Nodes to the left of Nodes to the left of the midline of the trachea the tracheal midline between the carina and between the upper margin of the aortic arch the left superior lobe bronchus, medial to the and the apex of the lung. Highest left mediasti- ligamentum arteriosum. nal nodes are included in this station. 11. Intrapulmonary nodes. Nodes removed in 4R. Right lower paratracheal nodes. Nodes to the the right or left lung specimen plus those dis- right of the midline of the trachea between the tal to the main bronchus. Interlobar, lobar, and cephalic margin of the azygos vein and the in- segmental nodes are included. In post-thora- tersection of the caudal margin of the brachio- cotomy staging they may be subdivided into cephalic artery with the right side of the tra- stations 11, 12, and 13, according to the AJCC chea. Some pretracheal and paracaval nodes classification. are included in this station. 4L. Left lower paratracheal nodes. Nodes to the In practice, the revisions to the AJCC classifications left of the midline of the trachea between the were as follows: upper margin of the aortic arch and the level – Stations 1, 2, 3, 5, 6, 7, 8, and 9 of the AJCC clas- of the carina, medial to the ligamentum arte- sifications have remained largely unchanged, riosum. Some pretracheal nodes are included but some have been renamed to adhere to the in this station. established guidelines. 5. Aortopulmonary nodes. Subaortic and para- – The pleural reflection is not taken as reference aortic nodes, lateral to the ligamentum arte- in the ATS classification because it is deemed riosum or the aorta or left pulmonary artery, not fixed and not radiologically identifiable. proximal to the first branch of the left pulmo- – The use of fixed anatomical landmarks is very nary artery. helpful to distinguish lymph nodes in critical 6. Anterior mediastinal nodes. Nodes anterior areas such as stations 4 and 10 (for example, to the ascending aorta or the innominate ar- 4R and 10R are separated by the azygos vein, tery. Some pretracheal and preaortic nodes are while 4L and 10L are separated by the level of included. the carina). 7. Subcarinal nodes. Nodes situated caudal to the tracheal carina but not associated with the A comparison between the two classifications is inferior lobe bronchus or the arteries within provided in Table 2.2 [32]. the lung. Ten years after these classifications were present- 16
  25. 25. Lymph Node Classification 2 Table 2.2 – Comparison between AJCC and ATS classifications Nodal AJCC classification ATS classification station 1 Highest mediastinal nodes Included in station 2 2 Upper paratracheal nodes Basically unchanged 3 Pretracheal and retrotracheal nodes If pretracheal, included in stations 2, 4, or 6 depending on anatomical location; if retrotracheal, they are included in station 8 4 Lower paratracheal nodes The boundaries of this “critical” station are defined 5 Subaortic nodes Called aortopulmonary to include the lymph nodes along the lateral as- pect of the aorta and the main or left pulmonary artery and the nodes of the aortopulmonary window 6 Para-aortic nodes Called anterior mediastinal nodes; they include some pretracheal and preaortic nodes 7 Subcarinal nodes Unchanged 8 Paraesophageal nodes Unchanged 9 Pulmonary ligament nodes Unchanged 10 Hilar nodes Called peribronchial on the left side and tracheobronchial on the right side 11 Interlobar nodes Classified as intrapulmonary 12 Lobar nodes Included in station 11 13 Segmental nodes Included in station 11 ed, the two systems were unified in the modified vascular and retrotracheal, para-aortic, subcarinal, classification of Naruke/ATS–LCSG. This classifica- and paraesophageal nodes. tion was adopted by the AJCC and by the UICC in In addition to the classifications illustrated above, 1996. other classifications have been developed by scien- In 1997 Mountain and Dresler [39, 40] published tific societies [41, 42] or groups of physicians [43]. the final version, which provides the anatomical Among these, the classification of the Japanese So- boundaries of the lymph node stations (Fig. 2.2). ciety for Esophageal Disease [41] has become quite This classification has had the merit of harmoniz- well known. ing the language of surgeons and pathologists in de- 105. Upper thoracic paraesophageal nodes. Lat- scribing the locoregional spread of lung cancer. eral to the upper thoracic esophagus, between The Mountain/Dresler unified classification in- the upper margin of the sternum and the tra- cludes 14 lymph node stations, identified by name cheal bifurcation. and number (Table 2.3). The lymph node stations 106. Thoracic paratracheal nodes. Lateral to the considered are those contained within the medi- thoracic trachea. astinal pleural reflection (called N2) and the hilar 107. Bifurcation nodes. Anterior to the esophagus, and intrapulmonary lymph nodes (called N1). N2 caudal to the tracheal bifurcation, and down to nodes include three groups: superior mediastinal the level of bifurcation of the main bronchi. nodes (1–4), aortic nodes (5, 6), and inferior me- 108. Middle thoracic paraesophageal nodes. diastinal nodes (7–9). The stations are bilateral (left Lateral and anterior to the middle thoracic and right) apart from the highest mediastinal, pre- esophagus (proximal portion between the 17
  26. 26. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy Fig. 2.2 AJCC/UICC classification by Mountain and Dresler. Mountain CF and Dresler CM (1997) [40] tracheal bifurcation and the esophagogastric This classification was modified and supplemented junction). in 1990 by Akiyama [44] who proposed the subdivi- 109. Pulmonary hilar nodes. In the pulmonary sion of esophageal lymph nodes into seven groups: hila around the vessels and main bronchi, after 1. Cervical lymph nodes their bifurcation. • Deep lateral nodes (spinal accessory nerve 110. Lower thoracic paraesophageal nodes. Lat- chain or level VB) eral and anterior to the lower thoracic esopha- • Deep external nodes (or level IV, lateral to the gus (distal portion between the tracheal bifur- internal jugular vein, including inferiorly the cation and the esophagogastric junction). supraclavicular nodes) 111. Diaphragmatic lymph nodes. Located around • Deep internal nodes (or level VI, medial to the the esophageal hiatus for 5 cm. jugular vein) 112. Posterior mediastinal nodes. Posterior to the 2. Superior mediastinal nodes esophagus, around the thoracic artery. • Recurrent laryngeal nerve lymphatic chain 18
  27. 27. Lymph Node Classification 2 Table 2.3 – AJCC/UICC classification by Mountain and Dresler Nodal station Description Superior mediastinal nodes 1 Highest mediastinal nodes Nodes lying above a horizontal line at the upper rim of the brachiocephalic (left innominate) vein where it ascends to the left, crossing in front of the trachea at its midline 2 Upper paratracheal nodes Nodes lying above a horizontal line drawn tangential to the upper margin of the aortic arch and below the inferior margin of no. 1 nodes 3 Prevascular and retrotracheal nodes May be designated 3A and 3P 4 Lower paratracheal nodes Nodes on the right: Located to the right of the midline of the trachea between a horizontal line drawn tangential to the upper margin of the aortic arch and a line extending across the right main bronchus at the upper margin of the upper lobe bronchus Nodes on the left: Lie to the left of the midline of the trachea between a hori- zontal line drawn tangential to the upper margin of the aortic arch and a line extending across the left main bronchus at the level of the upper margin of the left upper lobe bronchus They are both contained within the mediastinal pleura. For study purposes lower paratracheal nodes can be divided into superior (4s) and inferior (4i). No. 4s nodes are defined by a horizontal line extending across the trachea and drawn tangential to the cephalic margin of the azygos vein. No. 4i nodes are defined by the lower margin of no. 4s and the caudal margin of no. 4 Aortic nodes 5 Subaortic nodes (aortopulmonary Subaortic nodes are lateral to the ligamentum arteriosum or the aorta or left window) pulmonary artery and proximal to the first branch of the left pulmonary artery and lie within the mediastinal pleural envelope 6 Para-aortic nodes (ascending aorta or Nodes lying anterior and lateral to the ascending aorta and the aortic arch or phrenic) the innominate artery, caudal to a line tangential to the aortic arch Inferior mediastinal nodes 7 Subcarinal nodes Nodes lying caudal to the tracheal carina, but not associated with the lower lobe bronchi or arteries within the lung 8 Paraesophageal nodes (below the Nodes lying adjacent to the esophageal wall and to the right or left of the mid- carina) line, excluding subcarinal nodes 9 Pulmonary ligament nodes Nodes lying within the pulmonary ligament, including those in the posterior wall and lower inferior pulmonary vein N1 nodes 10 Hilar nodes The proximal lobar nodes, distal to the mediastinal pleural reflection and the nodes adjacent to the bronchus intermedius on the right 11 Interlobar nodes Nodes lying between the lobar bronchi 12 Lobar nodes Nodes adjacent to the distal lobar bronchi 13 Segmental nodes Nodes adjacent to the segmental bronchi 14 Subsegmental nodes Nodes adjacent to the subsegmental bronchi Source: Mountain CF and Dresler CM (1997) [40] 19
  28. 28. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy • Paratracheal nodes Table 2.4 – RTOG classification of lymph nodes drain- ing esophageal cancer • Nodes of brachiocephalic trunk • Paraesophageal nodes Station Description • Nodes of infra-aortic arch 1 Supraclavicular nodes 3. Middle mediastinal nodes 2R Right upper paratracheal nodes • Nodes of tracheal bifurcation 2L Left upper paratracheal nodes • Pulmonary hilar nodes 3P Posterior mediastinal nodes • Paraesophageal nodes 4R Right lower paratracheal nodes 4. Lower mediastinal nodes 4L Left lower paratracheal nodes • Paraesophageal nodes 5 Aortopulmonary nodes • Diaphragmatic nodes 6 Anterior mediastinal nodes 5. Superior gastric lymph nodes 7 Subcarinal nodes • Paracardiac nodes 8M Middle paraesophageal nodes • Nodes of lesser curvature 8L Lower paraesophageal nodes • Nodes of left gastric artery 9 Pulmonary ligament nodes 6. Celiac trunk nodes 10R Right tracheobronchial nodes 7. Common hepatic artery nodes 10L Left tracheobronchial nodes 15 Diaphragmatic nodes To help characterize the nodes of the esophageal 16 Paracardiac nodes region, the Radiation Therapy Oncology Group 17 Left gastric artery nodes (RTOG) proposed a classification [45] simply add- 18 Common hepatic artery nodes ing new lymph node stations to the already known 19 Splenic artery nodes ones for lung cancer staging (Table 2.4). 20 Celiac nodes 2.3 Upper Abdominal Region The first detailed description of upper abdominal region nodes was provided by Rouvière [3]. In 1962 the Japanese Research Society for Gastric cer sites, and analysis of survival with respect to the Cancer (JRSGC) published in Japanese the General involvement of the various lymph node stations. Rules for Gastric Cancer Study, which were used by In 1998 the JRSGC was transformed into the surgeons and oncologists for about 30 years with Japanese Gastric Cancer Association (JGCA) and several new editions. The first English edition [46] the 13th edition of the General Rules [48] was pub- was published in 1995 and was based on the 12th lished, together with the second English edition Japanese edition of the General Rules [47]. of the JGCA classification [49]. Both publications These publications introduced a classification introduced changes in gastric cancer staging, spe- of the lymph node stations draining the stomach. cifically as regards pathological staging and lymph These lymph nodes are numbered from 1 to 16 and node dissection [50]. The previous four-group clas- are classified into four groups according to the loca- sification system was replaced by a system including tion of the primary cancer site. Definition of these three groups distinguished in accordance with the groups derived from the results of studies on lym- gastric site of the primary cancer; a more accurate phatic spread patterns from different primary can- definition of lymph node groups 11 and 12 was pro- 20
  29. 29. Lymph Node Classification 2 vided; and a new lymph node dissection classifica- creas Society [51], the Liver Cancer Study Group of tion was proposed based on the lymph node groups Japan [52], and the Japanese Society of Biliary Sur- removed (D0-D1-D2-D3). gery) and the associated staging systems for tumors Lymph node stations according to the Japanese of the pancreas, of the hepatic and extrahepatic bil- classification are shown in Fig. 2.3 and listed in Ta- iary tracts, and of the liver have been subsequently ble 2.5, while their subdivision into three groups is modified [53–56]. shown in Table 2.6. For instance, the Japan Pancreas Society pub- Also for pancreatic, biliary, and hepatic regions, lished the first English edition of the Classification of lymph node classifications have been published by Pancreatic Carcinoma in 1996 [56]. This edition was the respective Japanese societies (the Japan Pan- based on the fourth Japanese edition of the General Fig. 2.3 a,b Illustration of the classification of regional lymph abdominal aorta. c Detail of the location of lymph nodes in the nodes of the stomach according to the Japanese Gastric Cancer esophageal hiatus of the diaphragm, of the infradiaphragmatic Association. a Anterior view with cross-section of stomach and nodes and para-aortic nodes. Japanese Gastric Cancer Associa- pancreas. b Detail of the location of the lymph nodes around the tion (1998) [49] 21
  30. 30. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy Table 2.5 – Classification of regional lymph nodes of the stomach according to the Japanese Gastric Cancer As- sociation (JGCA) Name Description 1 Right paracardial nodes Located at the level of the esophagogastric junction, along the branch of the left gastric artery 2 Left paracardial nodes Located to the left of the cardia. They also include the lymph nodes around the cardioesophageal branches of the inferior diaphragmatic artery 3 Nodes along the lesser gastric curvature On the lesser curvature of the stomach, along the lower branch of the left gastric artery 4 Nodes along the greater gastric curvature Located around the gastroepiploic arteries, they are therefore located close to the greater curvature of the stomach; they are subdivided, based on blood flow, into right-side nodes (4d nodes along the right gastroepiploic vessels), around the right epiploic artery beyond the level of the first collat- eral leading to the stomach, and left-side nodes (4s). The left-side nodes are further subdivided into proximal (4sa nodes along the short gastric ves- sels), located at the level of the short vessels, and distal (4sb nodes along the left gastroepiploic vessels), located along the left gastroepiploic artery 5 Suprapyloric nodes Located around the right gastric artery and close to the upper pylorus, downward lymph nodes 3 6 Subpyloric nodes Located at the level of the lower pylorus and around the right gastroepiploic artery, from its point of origin to the origin of the lateral branch heading toward the greater gastric curvature 7 Nodes along the left gastric artery Located at the level of the left gastric artery, between its origin from the celiac trunk and its left end at the level of the stomach, where it divides into its two terminal branches 8 Nodes along the common hepatic artery Located along the common hepatic artery, from its point of origin to the hepatic artery, at the point of origin of the gastroduodenal artery; they are subdivided into: – 8a anterosuperior group – 8p posterior group 9 Nodes around the celiac artery Located around the celiac trunk; they include the lymph nodes around the origins of the hepatic artery and splenic artery 10 Nodes at the splenic hilum Located at the level of the splenic hilum, beyond the tail of the pancreas; they are separated from lymph nodes 4sb through the first gastric collateral of the gastroepiploic artery 11 Nodes along the splenic artery They include the lymph nodes located along the splenic artery, the celiac trunk, and the final portion of the tail of pancreas; they are subdivided into: – 11p proximal – 11d distal 12 Nodes of hepatoduodenal ligament They are divided into three subgroups: – 12a along the hepatic artery, located at the level of the upper left of the hepatic pedicle and of the hepatic artery proper – 12b along the bile duct, on the right side of the common hepatic artery and the lower common bile duct – 12p behind the portal vein, located posterior to the portal vein 13 Posterior pancreaticoduodenal nodes Located on the posterior aspect of the head of the pancreas 14a Nodes along the superior mesenteric Located along the superior mesenteric artery, at the root of the mesentery artery 14v Nodes along the superior mesenteric vein Located along the superior mesenteric vein, at the root of the mesentery 15 Nodes along the middle colic vessels Located around the middle colic artery 22
  31. 31. Lymph Node Classification 2 Table 2.5 – (continued) Classification of regional lymph nodes of the stomach according to the Japanese Gastric Cancer Association (JGCA) Name Description 16a1 Nodes of the aortic hiatus 16a2 Nodes around the abdominal aorta (from the upper margin of the celiac trunk to the lower margin of the left renal vein) 16b1 Nodes around the abdominal aorta (from They include the lymph nodes around the abdominal aorta; they are the lower margin of the left renal vein to bordered laterally by the corresponding renal hila the upper margin of the inferior mesen- teric artery) 16b2 Nodes around the abdominal aorta (from the upper margin of the inferior mesen- teric artery to the aortic bifurcation) 17 Nodes on the anterior aspect of the pan- Located on to the anterior aspect of the head of the pancreas creatic head 18 Nodes along the inferior margin of the Located along the inferior margin of the pancreas pancreas 19 Infradiaphragmatic nodes Located below the diaphragm 20 Nodes of the esophageal hiatus of the diaphragm 110 Paraesophageal nodes of the lower chest Included in the Japanese stomach tumor classification when invasion of the esophagus occurs 111 Supradiaphragmatic nodes 112 Posterior mediastinal nodes Table 2.6 – Groupings of the regional lymph nodes of the stomach (groups 1–3) according to the Japanese Gastric Cancer Association Lymph nodes Location LMU/MUL LD/L LM/M/ML MU/UM U E+ MLU/UML 1 Right paracardial nodes 1 2 1 1 1 2 Left paracardial nodes 1 Met 3 1 1 3 Nodes along the lesser curvature 1 1 1 1 1 4sa Nodes along the short gastric vessels 1 Met 3 1 1 4sb Nodes along the left gastroepiploic vessels 1 3 1 1 1 4d Nodes along the right gastroepiploic vessels 1 1 1 1 2 5 Suprapyloric nodes 1 1 1 1 3 6 Infrapyloric nodes 1 1 1 1 3 7 Nodes along the left gastric artery 2 2 2 2 2 Met: lymph nodes regarded as distant metastasis, E+: lymph node stations reclassified in case of esophageal invasion, U, M, L, D: indicate the different parts of the stomach (U upper third, M middle third, L lower third) and invasion sites (D duodenum). If more than one side of the stomach is involved, the different sides must be listed by decreasing degree of involvement, with the first letter indicating the side in which the bulky tumor is located Source: Japanese Gastric Cancer Association (1998) [49] 23
  32. 32. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy Table 2.6 – (continued) Groupings of the regional lymph nodes of the stomach (groups 1–3) according to the Japa- nese Gastric Cancer Association Lymph nodes Location LMU/MUL LD/L LM/M/ML MU/UM U E+ MLU/UML 8a Nodes along the common hepatic artery (anterosuperior 2 2 2 2 2 group) 8b Nodes along the common hepatic artery (posterior group) 3 3 3 3 3 9 Nodes around the celiac artery 2 2 2 2 2 10 Nodes at the splenic hilum 2 Met 3 2 2 11p Nodes along the proximal splenic artery 2 2 2 2 2 11d Nodes along the distal splenic artery 2 Met 3 2 2 12a Nodes of the hepatoduodenal ligament (along the hepatic 2 2 2 2 3 artery) 12b Nodes of the hepatoduodenal ligament (along the bile 3 3 3 3 3 duct) 12p Nodes of the hepatoduodenal ligament (behind the portal 3 3 3 3 3 vein) 13 Nodes on the posterior aspect of the pancreatic head 3 3 3 Met Met 14a Nodes along the superior mesenteric artery Met Met Met Met Met 14v Nodes along the superior mesenteric vein 2 2 3 3 Met 15 Nodes along the middle colic vessels Met Met Met Met Met 16a1 Nodes of the aortic hiatus Met Met Met Met Met 16a2 Nodes around the abdominal aorta (from the upper 3 3 3 3 3 margin of the celiac trunk to the lower margin of the left renal vein) 16b1 Nodes around the abdominal aorta (from the lower margin 3 3 3 3 3 of the left renal vein to the upper margin of the inferior mesenteric artery) 16b2 Nodes around the abdominal aorta (from the upper mar- Met Met Met Met Met gin of the inferior mesenteric artery to the aortic bifurca- tion) 17 Nodes on the anterior aspect of the pancreatic head Met Met Met Met Met 18 Nodes along the inferior margin of the pancreas Met Met Met Met Met 19 Infradiaphragmatic nodes 3 Met Met 3 3 2 20 Nodes in the esophageal hiatus of the diaphragm 3 Met Met 3 3 1 110 Paraesophageal nodes in the lower chest Met Met Met Met Met 3 111 Supradiaphragmatic nodes Met Met Met Met Met 3 112 Posterior mediastinal nodes Met Met Met Met Met 3 Met: lymph nodes regarded as distant metastasis, E+: lymph node stations reclassified in case of esophageal invasion, U, M, L, D: indicate the different parts of the stomach (U upper third, M middle third, L lower third) and invasion sites (D duodenum). If more than one side of the stomach is involved, the different sides must be listed by decreasing degree of involvement, with the first letter indicating the side in which the bulky tumor is located Source: Japanese Gastric Cancer Association (1998) [49] 24
  33. 33. Lymph Node Classification 2 Rules for the Study of Pancreatic Cancer published in only difference is that some lymph node groups are 1993 [55] (the previous Japanese editions had been further subdivided, specifically: published in 1980 [51], 1982 [53], and 1986 [54]). In • Lymph nodes 12 (nodes of the hepatoduodenal 1997, the Review Committee of the General Rules ligament) are further subdivided into: for the Study of Pancreatic Cancer made a compari- – 12a1 and 12a2, 12b1 and 12b2, 12p1 and son between the Japanese classification and the fifth 12p2 (where numbers 1 and 2 differentiate edition of the UICC classification [57]. On this basis, the lymph nodes into superior and inferior it started preparing the fifth edition of the General groups, respectively) Rules, taking into consideration the limitations and • Lymph nodes 13 (posterior pancreaticoduode- advantages of both classifications. Unfortunately, nal) are further subdivided into: when in 2002 the fifth edition of the General Rules – 13a (superior group) and 13b (inferior group) was published, at the same time the sixth edition of • Lymph nodes 14 (nodes along the superior mes- the UICC classification was released, and it was not enteric artery) are further subdivided into: possible to include in the new General Rules [58, – 14a: Nodes at the origin of the superior mes- 59] the changes introduced in the latest edition of enteric artery the UICC classification. – 14b: Nodes at the origin of the inferior pan- The classifications proposed do not differ as to creaticoduodenal artery the nomenclature and numbering from the classifi- – 14c: Nodes at the origin of the middle colic cation of lymph node stations of the stomach, which artery we have therefore taken as reference for the entire – 14d: Nodes at the origin of the jejunal arteries upper abdominal region. For instance, the classi- • Lymph nodes 17 (anterior pancreaticoduodenal) fication of the main lymph node stations draining are further subdivided into: the pancreas includes lymph nodes already listed for – 17a (superior group) and 17b (inferior group) gastric cancer from 5 to 18 (Fig. 2.4) [60, 61]. The Fig. 2.4 Main lymph node sta- tions draining the pancreas. SMA superior mesenteric artery, IPD inferior pancreatoduodenal artery, MC middle colic artery, J jejunal artery. Adapted from Pedrazzoli S, Beger HG, Obertop H et al. (1999) [61] 25
  34. 34. A Guide for D elineation of Lymph Nodal Clinical Target Volume in R adiation Therapy 2.4 Pelvic Region narrow, making it difficult to evaluate the anatomi- cal boundaries of individual lymph node stations; As mentioned by Gregoire [6], lymph drainage of detailed pathological examination of these lymph the pelvis has been described in anatomy and sur- nodes is moreover altered by infiltrating fatty and gery textbooks but, unlike other anatomical re- fibrous tissue and by inflammation. gions, such as the head and neck and mediastinum As for the lymph nodes draining the female geni- regions, there is no universally accepted classifica- talia, after the initial description of the lymphatic tion. The lack of a standard nomenclature largely system made by Reiffenstuhl [62] in 1964 and Plentl derives from the technical difficulties involved in and Friedman [63] in 1971, an attempt to establish a the identification, surgical dissection, and anatomi- classification of the lymph nodes of interest to gyne- copathological evaluation of pelvic lymph nodes. cological oncology was made by Mangan et al. [64]. For instance, the nodes located along the pelvic These authors proposed a system including nine walls are continuously connected to the internal and major lymph node groups: external iliac vessels and therefore cannot be char- • Group 1. Para-aortic lymph nodes acterized distinctly. Moreover, the surgical field is • Group 2. Common iliac lymph nodes Table 2.7 – Subdivision of paraaortic and pelvic lymph nodes Type Description Para-aortic lymph nodes Paracaval nodes Located to the right of the vena cava Precaval nodes Located anterior to the vena cava Postcaval nodes Located posterior to the vena cava when the vein is mobilized to the left Deep intercavoaortic nodes To the right of the aorta, between the aorta and the vena cava, above the lumbar vessels Superficial intercavoaortic nodes To the right of the aorta, between the aorta and the vena cava, below the lumbar vessels Preaortic nodes Anterior to the aorta Para-aortic nodes Lateral to the aorta Postaortic nodes Posterior to the aorta Pelvic lymph nodes Common iliac nodes Around the common iliac vessels – Medial subgroup – Superficial lateral subgroup – Deep lateral subgroup In a space delimited laterally by the psoas muscle, medially by the common iliac vein and by the two iliolumbar veins, and posteriorly by the ischiatic nerve and by the origin of the obturator nerve External iliac nodes Internal iliac nodes Deep obturator nodes Superficial obturator nodes Presacral nodes Parametrial nodes 26
  35. 35. Lymph Node Classification 2 • Groups 3 and 4. External iliac lymph nodes aortic lymph node dissection in patients affected • Group 5. Obturator lymph nodes by gynecological tumors, in order to evaluate the • Group 6. Inferior gluteal lymph nodes number of nodes present in each lymph node group • Group 7. Hypogastric lymph nodes (internal and review existing nomenclature [65]. This study iliac) divided para-aortic nodes into eight groups and pel- • Groups 8 and 9. Presacral lymph nodes vic nodes into seven groups (Table 2.7). We agree with Gregoire [6] in believing that the While these studies played a key role for the un- pelvic lymph node classification most suitable for derstanding of the lymphatic pathways of ovarian radiotherapy planning is the one that associates tumors, this classification was not widely adopted. lymph node groups with the distribution of the In 1992 a study was published on pelvic and para- main arteries. For this classification, see Chapter 1. 27

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