Post op rt in oral cavity cancers

1. POST OP RADIOTHERAPY IN
ORAL CAVITY CANCER
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2. Anatomy
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3. Radiological anatomy
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4. Overview
 Cancers of oral cavity - 30% of head and neck
region tumors & 3% of all cancers
 Lips - most commonly involved
 90 % of oral cavity - cancers are moderately
differentiated squamus cell carcinoma
 Oral cavity cancer - 11th most common
cancer in the world
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5. Clinical Presentation
 Non healing painless ulcer, painful in advanced stage
 Ulcero proliferative or exophytic growth
 Cervical lymphadenopathy
 Trismus
 Dysphagia, odynophagia
 Bleeding from oral cavity
 Distant mets – lungs, liver, bones, brain
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6. Pre-treatment Workup
 History and physical examination, complete
head and neck exam
 Biopsy
 CE-MRI and/or CECT face & neck
 CT Chest
 FDG PET-CT in stage III/IV
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7. Staging- AJCC 8th edition
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9. Treatment Goals
 Cure
 Preservation or restoration of form and
function
 Minimize sequelae of treatment
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10. Factors affecting choice of treatment
Tumor factor
Size
Site
Location
Depth of invasion
Grade
Previous treatment
Patient factor
Age
General condition
Performance status
Previous treatment
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11. Treatment options
 Surgery
 Radiotherapy
 Chemotherapy
 Targeted therapy
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12. Treatment of Choice
 Stage I and II : single modality treatment
(surgery or radiotherapy) is effective and
preferable
 Stage III and IV : multimodal therapy is
essential
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13. NCCN Guidelines Version 1.2018
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14. Adverse risk features:
 Extra-nodal extension,
 Positive margins,

 pT3 or pT4 primary,
 N2 or N3 nodal disease,
 Nodal disease in levels IV or V,
 Peri-neural invasion, Vascular embolism,
Lymphatic invasion
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15. 15-Apr-18

16. Surgical management
 Most commonly treated with surgery in early stage
 Successful treatment relies on effective management of
regional lymphatics as well as primary cancer
 Elective neck surgery - in patient with clinically negative
neck node
 Therapeutic neck dissection – clinically apparent nodal
disease
 Early stage T1/2 No tumor : Wide excision +/ - ND
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17. Surgical management oral cavity
 Trans-oral approach
 Trans cervical (pull through)
 Mandibulectomy
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18. Surgical approach depends on
Tumor site- approximate with gingiva and periosteum, Marginal
mandibulectomy
Tumor extent- Rim Mandibulectomy
Sagittal mandibulectomy
Proximity to mandible or maxilla
Need for neck dissection
Need for reconstructive surgery
Marginal
mandibulectomy
Segmental
mandibulectomy 15-Apr-18

19. Radiotherapy
 Radical : early stage
 Palliative : advanced stages
 Combined therapy
 Preoperative (neoadjuvant)
 Postoperative (adjuvant)
 Mode of delivery -
 External beam radiation therapy (EBRT)
 Brachytherapy
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20. Radiotherapy alone
 T1 and early T2 tumors
 Combined approach – including EBRT and interstitial
brachytherapy is often recommended
 The normal tissue toxicity may render radiation therapy a
less attractive option or single modality treatment
 Sites- lip, floor of mouth, oral tongue
 The outcome for advance lesion of the oral cavity (T3 and
T4) are less than satisfactory with either surgery or
radiation alone
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21. Adjuvant (Post-op) RT
Aims :
To prevent local recurrence
To control occult disease in the cervical lymph nodes that were not
resected surgically
Indications :
-Presence of nodal disease with exptracapsular spread.
-Presence of involved surgical margin
-Excision margin less than 5 mm
-Stage III/IV
-Perineural or vascular invasion
-Poor differentiation
-Soft tissue invasion
-Mandibular bone involvement 15-Apr-18

22. Factors that determine adjuvant t/t
 Adequacy of Surgery
 Margin
 Lymph nodes dissected
 Gross & microscopic characteristics of the primary lesion
 Gross & microscopic characteristics of dissected lymph
nodes
 Patterns of spread
 Frequency and pattern of lymph node involvement
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23.  Buccal Mucosa lesions
involve the buccinator
muscle and buccal fat pad
 Alveolar and retromolar
trigone lesions involve bone
early;
 Mandibular canal and
inferior alveolar nerve /
maxillary antrum and floor of
nose – potential routes &
sites of spread, respectively.
 Bone Involvement :
Absence of fixation to bone /
small size of a mandibular
lesion, does not rule our
bone involvement.
 ITF
Yao et al IJROBP 2007 :
55 pts, oral cancer alone
Mostly post-op IMRT
2/9 locoregional failures in ITF
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24. Post op RT
RTOG 73-03 :
 Locally advanced H & N cancers
 Preop (50 Gy) vs Postop (60 Gy)
 Oral cavity also had definitive RT arm (65-70 Gy) followed
by surgery if residual cancer
 Head Neck Surg 1987;10:19-30
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25.  RTOG 73-03
 277 patients
 10 year follow-up
 Improved locoregional control in post-op RT arm
(65%) vs. pre-op RT (48%, p=0.04)
 Trend toward improved survival : 38% vs 33%, p=0.10)
 Surgical and radiation therapy complications “similar”
 IJROBP 1991;20:21-8.
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26.  RTOG 7303 established 60 Gy as post-op RT dose
 MD Anderson performed prospective randomized trial
evaluating RT dose for 240 patients with resected stage
III/IV cancers of oral cavity, oropharynx, hypopharynx,
larynx
 180 cGy fractions
 Dose ranged from 52.2 Gy to 68.4 Gy
 IJROBP 1993; 26:3-11.
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27.  Patients receiving <54 Gy had significantly higher failure rate
 No dose response beyond 57.6 Gy except for patients with
extracapsular nodal spread
 ECE+ needed at least 63 Gy
 “Clusters” which predicted increased risk of failure
 oral cavity primary,
 positive/close margins,
 nerve invasion,
 >2 positive nodes, largest node >3 cm,
 treatment delay >6weeks,
 Zubrod performance status>2
 Moderate to severe complications seen in 7.1%; more if RT dose
>63 Gy
 Dose escalation above 63 Gy “does not appear to improve the
therapeutic ratio”
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28. Post-operative chemo-radiotherapy
 Shift in the treatment paradigm
 RTOG9501 and EORTC 22931 – all the patient with
resected head and neck cancer with positive margin
or extranodal extension should be assigned to
combined chemoradiation approach using concurrent
cisplatin
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29. Patient Selection Criterion
EORTC 22931 only
EORTC 22931 and RTOG
9501 RTOG 9501 only
Stage III/IV disease
Surgical margins
microscopically involved
Two or more
positive lymph
nodes
Positive lymph nodes at
levels IV or V in patients
with tumors arising from
oropharynx or oral cavity
Extracapsular extension in
positive lymph nodes
Vascular embolisms
Perineural infiltration
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30.  Post op RT alone v/s
 Post op RT + Cisplatin 100 mg/m2 on weeks 1, 4 and 7
 EORTC Trial - 334 patients were treated. There was a
significant benefit for 3 yr overall survival ( 61% v 49%)
 DFS, LRC, and time to progression favoring the CRT
arm.
 Although acute functional mucosal reactions were
worse in the CRT arm than the RT arm, there were no
differences seen in late toxicities.
 RTOG 459 high risk patients - similar results
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32. Treatment techniques
 Conventional – 2D
 3DCRT
 IMRT
 IGRT
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33. Techniques of RT
 Carcinoma of the oral cavity - opposed lateral fields,
using either 2D or 3D CT-based techniques
 During simulation and treatment patients are commonly
immobilized with a thermoplastic mask
 Placed in supine position with a bite block (for oral
tongue and floor of mouth cases) to depress the tongue
away from the palate
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34. . For patients with a short neck, the shoulders are
depressed by having the patient pull on a tensioning
device looped beneath the feet
 Generally, the oral cavity tumor bed and upper echelon
lymph nodes are included within the initial lateral fields
 The upper border of the field is positioned to provide a
1.5- to 2-cm border on the tumor bed
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36.  The inferior border - thyroid notch, just above the true vocal cords
 The posterior border - mid-vertebral body level if level V nodal coverage is
not required
 The nodal volume should include level Ia-Ib, II, and III
 Advanced neck disease or risk of positive level V lymph nodes, where the
posterior chain requires radiation, the initial fields should be set behind
the C1 vertebral body spinous process
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37.  The portals are then reduced at approximately 45 Gy to spare
high dose to the spinal cord
 If + ve cervical lymph node metastases, or high-risk disease, then
the lower neck will also be treated
 In this case, a single half-beam-blocked anteroposterior field is
matched to the inferior border of the opposed lateral fields at the
level of the thyroid notch
 An anterior larynx block is used, which protects not only the central
larynx from unnecessary radiation dose, but also protects against
spinal cord overdose due to three-field overlap
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38.  Megavoltage beams with an energy range between 4 and
6 MV are most suitable for treatment of cancers involving
the oral cavity
 Cobalt-60 (similar average energy to that from 4 MV
linear accelerators) remains a very acceptable radiation
delivery unit for cancers in this region owing to the small
lateral separation distances in the head and neck area
 When higher energy beams are used, bolus material
may be necessary to bring dose to the surface as
required for tumors that extend to the skin
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39.  Postoperative radiation the most common dose
fractionation is 1.8 to 2.0 Gy per day
 Dissected tissues that harbored the original tumor should
generally receive on the order of 60 Gy
 Close or positive microscopic margins or extracapsular
nodal extension, a 4 to 6 Gy localized boost should be
considered
 Gross residual disease, either further surgical resection
or focal boosting up to 70 Gy is advisable
 Low risk (i.e., clinically or pathologically uninvolved
necks) should receive on the order of 50 to 54 Gy 15-Apr-18

40. CRT - Work Flow
 CT simulation
 Target Volume Delineation
 Planning
Plan Approval
Treatment plan Verification
Treatment Execution
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41. Conformal Radiotherapy
Immobilization Devices used
•Head Rest alone
•POP with Head Rest
•Mouth Bite, Nasion & Chin
support
•Thermoplastic Moulds
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42. Immobilization
 Cast is fixed to the couch top or base plate in at least 3
places
 Mouth bite - pushes the tongue inferiorly when irradiating
the hard palate or upper alveolus and separate the roof of
the mouth from the inferior oral cavity when irradiating the
tongue
 Pull the shoulders inferiorly
 Anterior and lateral reference
marks made on the mould
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43. Head and Neck Immobilization devices
3
Clamp
4
Clamp
5
ClampRandom Errors with different Fixation devices
Radiotherapy
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44. CT Simulation & Data Acquisition
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45. Target Delineation
 Images are transferred from CT Simulator to TPS
where Target delineation is done. OAR
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46. Treatment Planning
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47. Plan verification and Approval
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48. Treatment implementation
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49. IMRT in Oral Cavity
Ideal candidate
 T1 to T4 lesion
 < or = to N2b
 IMRT may not be required for all patient T1-2/N0
as bulk of parotid glands can be excluded from
opposed lateral portals.
 Patient with I/L +ve neck node IMRT may allow
dose limitation to C/L parotid gland
 In B/L (N2c) neck disease its difficult to spare the
parotid gland
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50. High risk CTV should include
 Primary tumor bed( based on preoperative
imaging, physical examination, operative finding)
 Grossly involved adenopathy
Intermediate risk CTV
 Pathologically + ve hemineck
 Nodal coverage for level I ,II, III, IV
Low risk CTV
 The uninvolved low or c/l neck
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51. 3DCRT v/s IMRT
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52.  CBCT (3 times/wk in 1 st week then 2 times/wk) or
Daily orthogonal portal images are implemented to
enhance daily set up reproducability
 PTV expansion on CTV may be limited to 2 to 5 mm
based on set up errors of institution
Dose :
 HR PTV – 60-66 Gy in @ Gy per fraction
 Microscopically +ve margin or ECE - 64-66 Gy
 IR PTV – 60 Gy
 LR CTV- 50-54 Gy
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53. Dose Limitation
 Spinal cord max dose < 45 Gy
 50% volume of each parotid < 20 Gy
 Mean parotid dose <26 Gy
 Mandible maximum (point dose) < 70 Gy
 Larynx Mean < 40 Gy
 Brain stem D Max < 54 Gy
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56. RT Complications
 Acute – within 3 months
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57. Radiation Dermatitis
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58. RT complications
 Late – After 6 months
 Xerostomia
 Dental caries
 Trismus
 Osteoradionecrosis
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