This document provides an overview of esophageal cancer, including the two main histologic types (squamous cell carcinoma and adenocarcinoma), routes of tumor spread, imaging features on CT, and the TNM staging system. Key points include: - Esophageal cancer most commonly presents as squamous cell carcinoma or adenocarcinoma. Adenocarcinoma has a better prognosis and is more commonly found in the distal esophagus. - The cancer can spread locally via direct extension or lymphatically. Distant metastases most often involve the liver, lungs, bones and other sites. - CT is useful for staging by evaluating wall thickness, lymph nodes, and invasion of nearby structures.

1. Dr.Yash Kumar Achantani
OSR

2. Introduction
Esophageal cancer is the third most common gastrointestinal
malignancy and is among the 10 most prevalent cancers worldwide.
As with all other tumors, the outcome for patients with esophageal
cancer is strongly associated with the stage at initial diagnosis.
Surgical resection is currently the best curative treatment for
patients without distant metastases or locally advanced tumor
growth.
Patients with locally advanced disease have a poor prognosis despite
aggressive attempts at resection, and patients with distant
metastatic disease are considered to have an incurable disease.

3. HistologicTypes
of Esophageal Cancer
More than 90% of esophageal cancers are either squamous cell
carcinomas (SCCs) or adenocarcinomas.
SCCs are evenly distributed between the middle and lower
esophagus, whereas approximately three-fourths of all
adenocarcinomas are found in the distal esophagus.
Esophageal adenocarcinoma has a better longterm prognosis after
resection than does SCC.

4. General imaging findings of malignancy include
1.Stricture or mass with mucosal irregularity or ulceration at barium
esophagography.
2.Evidence of tumor spread with infiltration of the periesophageal
fat, lymphadenopathy, or distant metastases at cross-sectional
imaging.
Given the overlapping imaging features of esophageal malignancies,
the main role of radiology is staging.

5. Squamous Cell Carcinoma
SCC is a malignant tumor of epithelial cells with stratified squamous
differentiation that progresses from precursor lesions of intraepithelial
neoplasia . It is the most common esophageal neoplasm worldwide .
SCC of the esophagus is more common in men than in women and its
prevalence increases with age: Approximately 65% of patients are
men, and the peak age group is 60–74 years of age.
Tobacco and alcohol use are the major risk factors for SCC of the
esophagus. Other risk factors include a diet low in fresh fruit and
vegetables or high in nitrosamines, achalasia, celiac disease, acid or lye
burns, and Plummer-Vinson syndrome.

6. Progressive dysphagia, odynophagia, and weight loss are the most
common symptoms of SCC of the esophagus .
Patients with mediastinal tumor invasion may have chest pain
unrelated to swallowing.
The majority of SCCs involve the middle third of the esophagus,
followed by the lower third and then the upper third.
These tumors can exhibit a variety of gross morphologic patterns,
appearing as polypoid, flat, or ulcerated lesions.

7. CT features
At CT, esophageal cancer causes localized thickening of the
esophageal wall or a soft-tissue mass.
Wall thickening may be asymmetric in early esophageal cancer and
progress to circumferential involvement.
SCC demonstrates peak enhancement in the late arterial phase (35
seconds) compared with more gradual enhancement of the normal
esophagus.
CT plays an important role in staging of esophageal cancer, especially
in evaluating mediastinal invasion and distant metastatic disease,
and may show complications, such as esophageal obstruction and
tracheoesophageal fistula formation.

8. SCC of the esophagus in a 51-year-old man.
Axial contrast-enhanced CT image shows concentric thickening of
the esophageal wall.

9. SCC of the midesophagus in a 52-year-old man.
Contrast material– enhanced CT scan obtained at the level of the left
superior pulmonary vein shows a small, nodular protruding
lesion (arrow).

10. SCC of the esophagus in a 67-
year-old man.
a) Coronal contrast-enhanced
CT image shows marked
thickening of the upper
thoracic esophageal wall
with an abrupt transition
inferiorly (arrows).The
esophagus is otherwise
diffusely dilated from
achalasia.
b) (b, c) Sagittal (b) and axial (c)
contrast-enhancedCT
images show displacement
and indentation of the
trachea (arrowheads),
findings consistent with
tracheal invasion.

11. An involved lymph node (arrow
in c) shows peripheral
enhancement from central
necrosis.
(d) Axial fused PET/ CT image
shows avid uptake by the
esophageal carcinoma
obscuring the involved lymph
node.

12. SCC of the esophagus in a 63-year-old.
Axial contrast-enhancedCT image shows concentric thickening of the
esophageal wall. Contact of the tumor with greater than 90° of the aortic
circumference (arrows) is concerning for aortic invasion, and stranding of
the adjacent fat (arrowhead) is consistent with mediastinal invasion.

13. Adenocarcinoma
Esophageal adenocarcinoma is a malignant epithelial neoplasm that
almost always arises from malignant degeneration of underlying
Barrett epithelium.
Barrett esophagus is a premalignant condition in which there is
replacement of the normal stratified squamous epithelium in the
esophagus by columnar epithelium as a result of chronic
gastroesophageal reflux and reflux esophagitis.
Rarely, adenocarcinoma can also arise from heterotopic mucosa in
the upper esophagus at or near the thoracic inlet.
Since most patients with Barrett esophagus are asymptomatic, the
true frequency of adenocarcinoma is unknown.

14. Patients with early esophageal adenocarcinoma are either
asymptomatic or have symptoms from their underlying
gastroesophageal reflux disease.
Most patients have advanced disease at the time of clinical
presentation, and symptoms are similar to those in patients with
advanced SCC.
These tumors are usually located in the lower third of the thoracic
esophagus.
Unlike SCCs, esophageal adenocarcinomas have a marked tendency
to invade the gastric cardia and fundus by direct extension across the
gastroesophageal junction.

15. CT features
Adenocarcinoma of the esophagus may be indistinguishable from
SCC at imaging on the basis of morphologic findings, but the vast
majority of adenocarcinomas involve the lower third of the
esophagus, and these tumors are much more likely to invade the
stomach.
Cross-sectional imaging features of esophageal adenocarcinoma
are similar to those of SCC, including asymmetric or circumferential
wall thickening, and findings of regional and distant spread.

16. Esophageal adenocarcinoma in a 62-year-old man.
Coronal contrast-enhanced CT (d) and fused PET/CT (e) images show diffuse wall
thickening of the distal esophagus (arrows) and an enlarged periesophageal
lymph node (arrowhead) with FDG uptake.

17. Esophageal adenocarcinoma in a 59-year-old woman.
Axial contrast-enhancedCT image shows a mass projecting into the
esophageal lumen (arrows).The mass is outlined by foci of air.

18. Mucinous adenocarcinoma of the gastroesophageal junction in a 52-year-old man.
Axial contrast-enhanced CT image shows a low-attenuation mass with scattered
punctate calcifications (arrows) involving the gastroesophageal junction and lesser
curvature of the stomach.

19. Routes ofTumor Spread
Esophageal cancer is notorious for its aggressive behavior; it may invade
local, regional, or distant structures by various pathways, including direct
extension, lymphatic spread, and hematogenous metastasis.
Direct Extension.—Because the esophageal wall lacks a serosa and is
attached to neighboring structures by only a loose connective adventitia,
there is no anatomic barrier to prevent rapid local extension of the tumor
into the mediastinum.
As a result, esophageal cancer can easily spread to adjacent structures in
the neck or thorax.
Tracheobronchial invasion may result in tracheoesophageal or
bronchoesophageal Fistulas.

20. Lymphatic Spread.—The esophagus has an extensive lymphatic
drainage system that consists of two lymphatic plexuses, one arising in
the mucosa and the other in the muscular layer.
The flow of lymph in the upper two-thirds of the esophagus tends to be
upward, whereas that in the distal third tends to be downward; however,
all lymphatic channels intercommunicate, and there is bidirectional flow
in the tracheal bifurcation.
Therefore, although tumors in the distal esophagus are more likely to
metastasize to the abdomen, lymphatic spread of cancer in the upper or
midesophagus can also result in metastasis to celiac or other
intraabdominal lymph nodes.
Hematogenous Metastasis.—Hematogenous metastases are often
found in patients with advanced esophageal cancer.
The most common sites include the liver, lungs, bones, adrenal glands,
kidneys, and brain, in descending order of frequency of occurrence.

21. Staging
The clinical staging of esophageal cancer is assessed with theTNM
system.
The depth of tumor invasion determines the primary tumor stage (T).
Nodal status (N) is based on the presence or absence of involvement
of locoregional lymph nodes.
Distant metastases is based on the presence (M1) or absence of (M0)
metastases.

22. Primary tumor
The degree of primary tumor invasion is represented by theT
classification, which provides details regarding local tumor invasion
into the esophageal wall and advanced invasion into adjacent
structures.
TheT classification is one of the important prognostic factors in
patients with esophageal cancer because a higherT category is
associated with a greater likelihood of nodal metastatic disease.
Furthermore, in general practice, theT classification is crucial to
determining suitability for surgical resection and establishing a
treatment plan.

23. T1–T3 Classifications.—T1 tumors invade the lamina propria or
muscularis mucosae (T1a) or submucosa (T1b).T2 tumors invade the
muscularis propria, andT3 tumors involve the adventitia of the
esophageal wall.
CT is one of the noninvasive imaging modalities used for staging
esophageal cancer. Normal esophageal wall thickness at CT is usually
less than 3 mm when the esophagus is distended, and any thickness
greater than 5 mm is considered abnormal.
T1 orT2 esophageal cancer is usually seen as an asymmetric
thickening of the esophageal wall.
T3 esophageal cancer can be seen at CT as definite wall thickening or
as an esophageal mass that causes luminal obstruction.
However, the use of CT is limited for determining the exact depth of
tumor invasion into the esophageal wall.

24. T1a tumor. (a) Axial contrast-enhancedCT image at the level of the right
pulmonary artery shows a suspicious small nodular lesion in the midesophagus
(arrow), a finding that is not easy to detect without endoscopy.The lesion was
later confirmed to be squamous cell carcinoma.

25. T1b tumor. (a) Axial contrast-enhancedCT image at the level of the left atrium
shows asymmetric wall thickening in the midesophagus (arrow), a finding later
confirmed to be squamous cell carcinoma.

26. T2 tumor. (a) Axial contrast-enhancedCT image at the level of the left atrium
shows an intraluminal mass in the midesophagus (arrow), a finding later
confirmed to be squamous cell carcinoma.

27. T3 tumor. (a) Axial contrast-enhanced CT image at the level of the left inferior
pulmonary vein shows diffuse wall thickening in the lower esophagus and
periesophageal fat infiltration, findings later confirmed to be squamous cell carcinoma.
Obliteration of the fat plane between the mass and the left atrium or descending
thoracic aorta is equivocal (arrowheads), and the triangular fat space is preserved
(arrow).

28. T4 Classification.—In the seventh edition of theTNM staging
system,T4 tumors that invade adjacent structures include the new
subcategorizations ofT4a andT4b, which are based on tumor
resectability.
T4a tumors are resectable cancers that invade adjacent structures
such as the pleura-peritoneum, pericardium, or diaphragm.
T4b tumors are unresectable cancers that invade other adjacent
structures such as the aorta, carotid vessels, azygos vein, trachea, left
main bronchus, or vertebral body.
CT criteria for local invasion include loss of the fat planes between
the tumor and adjacent structures in the mediastinum and
displacement or indentation of adjacent mediastinal structures.

29. Pericardial invasion is suspected if CT images show obliteration of
the fat plane between the esophageal mass and pericardium,
pericardial thickening, pericardial effusion, or indentation of the
heart with a concave deformity.
A tracheobronchial fistula or direct extension into the lumen is an
unequivocal finding of airway invasion by the tumor.
Tracheobronchial invasion is also suspected if there is a discrete
indentation on the posterior wall or displacement of the trachea or
bronchus by the tumor.
Aortic invasion is suggested if the contact area between the tumor
and aorta is greater than 90° or if there is obliteration of the
triangular fat space between the esophagus, aorta, and spine
adjacent to the primary tumor.

30. T4b tumor with tracheobronchial invasion. (a, b) Axial contrast-enhanced CT images at
the level of the tracheal bifurcation and main-stem bronchi show diffuse wall thickening
in the midesophagus (*), a finding later confirmed to be squamous cell carcinoma.
Direct tumor extension into the carina and left main bronchus is seen as carinal blunting
(arrow in a) and luminal narrowing of the left main bronchus (arrow in b).

31. T4b tumor with aortic and bronchial invasion. Axial contrast-enhanced CT image at the
level of the right main pulmonary artery shows diffuse irregular wall thickening in the
midesophagus.The tumor contacts the descending thoracic aorta at greater than 90°
(arrowheads) and obliterates the triangular fat space between the esophagus and thoracic
aorta (arrow). Surgery confirmed squamous cell carcinoma.

33. Drawing illustrates the revisedTNM
staging system for esophageal cancer
(seventh edition).

34. Regional Lymph Nodes
The N classification, which considers regional lymph node
involvement, is the most important prognostic factor in esophageal
cancer because patients without lymph node involvement have a
better prognosis than those with nodal involvement.
The revised manual defines regional lymph nodes to include any
paraesophageal lymph nodes from the cervical nodes to the celiac
nodes.
The new N classification comprises N0 (no cancer-positive nodes), N1
(one or two cancer-positive nodes), N2 (three to six cancer-positive
nodes), and N3 (seven or more cancer-positive nodes).

35. At CT, normal lymph nodes are usually smaller than 1 cm in short-axis
diameter and have a smooth well-defined border, uniform
homogeneous attenuation, and a central fatty hilum.
Intrathoracic and abdominal lymph nodes larger than 1 cm and
supraclavicular lymph nodes larger than 5 mm in short-axis diameter
are considered metastatic lymph nodes.
However, normal-sized lymph nodes that contain microscopic
metastatic foci cannot be differentiated from nonmetastatic lymph
nodes at CT and can lead to understaging, and benign, enlarged,
inflammatory lymph nodes seen at CT may lead to overstaging.
In addition, metastatic lymph nodes adjacent to esophageal cancer
may not be detected because they are inseparable from the primary
tumor . If there are conglomerated lymph nodes, the number of
lymph node metastases cannot be accurately measured, and
determining the N category can be difficult.

36. N1 disease. (a) Axial contrast-enhanced CT image shows an enlarged right
supraclavicular lymph node (arrow) measuring 11 mm in short diameter.
Surgery confirmed squamous cell carcinoma with a malignant lymph node (N1 disease).

37. N2 disease. (a) Axial contrast-enhanced CT image at the level of the aortic arch shows
asymmetric wall thickening (*) in the upper esophagus and an enlarged paraesophageal
lymph node (arrow). Another small paraesophageal lymph node was also seen (not shown).
(b) Axial contrast-enhanced CT image shows an enlarged right supraclavicular lymph node
(arrow) measuring 32 mm in short diameter. Surgery confirmed squamous cell carcinoma
with three malignant lymph nodes (N2 disease)

38. N3 disease. (a) Axial contrast-enhanced CT image shows conglomerated lymph
nodes with encasement of the left gastric artery (arrow).

40. Regional lymph nodes according to
the seventh edition of the staging
manual for esophageal cancer.
1L = left supraclavicular, 1R = right
supraclavicular, 2L = left upper
paratracheal, 2R = right upper
paratracheal, 4L = left lower
paratracheal, 4R = right lower
paratracheal, 5 = aortopulmonary,
6 = anterior mediastinal, 7 =
subcarinal, 8L = lower
paraesophageal, 8M = middle
paraesophageal, 9 = pulmonary
ligament, 10L = left
tracheobronchial, 10R = right
tracheobronchial, 15 =
diaphragmatic, 16 = paracardial, 17
= left gastric, 18 = common
hepatic, 19 = splenic, 20 = celiac.
The posterior mediastinal lymph
node (3P) is not shown.

41. Distant Metastases
Tumor involvement through hematogenous metastases to distant
organs is defined as the M classification and is an important factor in
determining operability.
The new M classification is simply designated M0 or M1 according to
the absence or presence of distant metastasis, respectively.
CT has been widely used for detection of distant metastases in the
initial staging of newly diagnosed esophageal cancer. Liver metastases
usually appear at CT as hypoattenuating ill-defined lesions that are
best visualized during the portal venous phase of liver enhancement.

42. Pulmonary metastases usually are round, smooth-bordered, and
noncalcified at CT.
In the case of bone metastases, CT has a lower sensitivity.
Adrenal metastases may be seen at CT as focal heterogeneous
enlargement of the adrenal gland, a finding that must be
differentiated from benign adrenal adenomas.

43. Adenocarcinoma. (a) Axial contrast-enhanced CT image at the level of the left atrium
shows an eccentric mass in the midesophagus (*).The lesion involves periesophageal fat,
and the fat plane between the mass and the pericardium of the left atrium is not
preserved, findings suggestive ofT4a disease that were later confirmed to be
adenocarcinoma. (b) Coronal PET image shows intense FDG uptake in the primary tumor
in the midesophagus (straight arrow) and in the right retrocrural and left gastric lymph
nodes (arrowheads). Unexpected intense FDG uptake is seen in the left humeral head
(curved arrow), a finding consistent with M1 disease.

44. Cancer Location
The esophagus is classically divided into four regions: cervical, upper
thoracic, middle thoracic, and lower thoracic.
In the seventh edition of the staging system the cervical esophagus,
which is 15–20 cm from the incisors at esophagoscopy, begins at the
level of the cricopharyngeus muscle and ends at the level of the
sternal notch.
The upper thoracic esophagus, which is 20–25 cm from the incisors, is
bounded superiorly by the sternal notch and inferiorly by the azygos
arch.
The middle thoracic esophagus, which is 25–30 cm from the incisors,
extends from the level of the azygos arch to the level of the inferior
pulmonary vein.

45. The lower thoracic esophagus is 30–40 cm from the incisors and
extends from the level of the inferior pulmonary vein to the lower
esophageal sphincter.
An important factor in assessing cancer location is to determine the
position of the upper edge of the tumor in the esophagus, not the
position where the tumor occupies the largest volume.
Additionally, the new concept of tumors that occur in the
esophagogastric junction has been addressed in the seventh edition
and states that adenocarcinomas of the esophagogastric junction as
tumors that have their center within 5 cm proximal and distal to the
anatomic cardia.
Therefore, tumors in the esophagogastric junction are staged as
esophageal cancer if (a) the tumor’s epicenter is within the lower
thoracic esophagus or at the esophagogastric junction or (b) the
epicenter is within the proximal 5 cm of the stomach and the tumor
extends into the esophagus

47. Cervical esophageal cancer. (a) Axial contrast-enhanced CT image at the level of the
thyroid gland shows irregular circumferential wall thickening in the cervical
esophagus, with direct tumor extension into the posterior wall of the trachea
(arrow).The lesion was later confirmed to be squamous cell carcinoma. (b) Coronal
PET/CT image shows intense FDG uptake in the primary tumor (arrow).

48. Involvement of the esophagogastric junction. (a) Axial contrast-enhanced CT image shows
diffuse wall thickening around the esophagogastric junction and an equivocal paracardial
lymph node measuring 10 mm in short-axis diameter (arrow). (b) Coronal PET image
shows intense FDG uptake in the primary tumor (arrow), which involves the
esophagogastric junction. At surgery, the findings were confirmed to be squamous cell
carcinoma with a malignant lymph node.

49. Involvement of the gastric cardia. Axial (a) and coronal (b) CT images show diffuse wall
thickening in the proximal 5 cm of the stomach (arrowheads), a finding that extends into
the esophagogastric junction (arrows). In the seventh edition of the staging manual, this
tumor is classified as esophageal cancer rather than as gastric cancer.

50. In the seventh edition Stages are made according to the anatomicT,
N, and M classifications and also nonanatomic cancer characteristics,
including histopathologic cell type, histologic grade, and cancer
location.

52. Stage-based Management