TNM Staging Atlas with Oncoanatomy, 2e

CHAPTER 21. Thoracic Esophagus

PERSPECTIVE, PATTERNS OF SPREAD, AND PATHOLOGY

Although the esophagus is thought of as a thoracic organ, cancers of the esophagus can arise in the neck and abdomen as well as the chest.

PERSPECTIVE AND PATTERNS OF SPREAD

Esophageal cancers vary in their presentation, depending on the anatomic site of origin: cervical, thoracic, or abdominal. This long, tubular structure is subject to a variety of stresses beginning with smoking and alcohol abuse and terminating with acid reflux and hiatal hernia. The histopathologic types reflect their histogenic origin (Table 21.2).

The incidence of esophageal cancers is approximately 16,640 new cases with an appalling 80% mortality rate unless the cancer is detected in its early stages. In some regions of the world, there is a very high prevalence, namely, northern provinces of China (20% of all cancer deaths), the Transkei province in South America (50% of all cancers), and the Gonbad region of northern Iran (200 times that of the United States). Numerous risk factors exist as aforementioned. Of interest is the early esophageal staging system. The Japanese have evolved an early staging system because of their increased and intensive screening and because this cancer is endemic in the Far East.

image

The concern for esophageal cancer is ulceration and perforation, which can lead to numerous disastrous complications, depending on the surrounding anatomy: in the upper third, tracheoesophageal fistulas, in the middle third, aortoesophageal perforation can lead to a fatal and rapid exsanguination, and in the lower third, pericardial tamponade can result in pulsus paradoxus and heart failure (Fig. 21.2Table 21.2).

The malignant gradient is high throughout, with more survivors in the cervical segment decreasing intrathoracically and least at the gastroesophageal junction because of the ease of cancer spread to infradiaphragmatic sites.

There are a wide variety of mediastinal tumors due to different origins of many tissues. The mediastinum is divided into four distinct compartments and each are prone to specific neoplasms. The anterior superior compartment contains the thymus and lymph nodes. Thus thymomas, thymic carcinomas, Hodgkin's lymphoma (HL), and non-Hodgkin's lymphomas are more common. The middle compartment contains the heart, which uncommonly is involved in neoplastic transformation into sarcomas. The anterior inferior compartment may give rise to germ cell tumors or germinomas that differentiate into different cell lives. The posterior compartment is prone to neurogenic tumors, from pediatric neuroblastomas to neurofibromas.

The esophagus transverses the posterior mediastinum and is the major site prone to develop squamous cell cancers, and at the cardia junction, to develop stomach adenocarcinomas.

image

Figure 21.1| A squamous cell carcinoma with a typical pattern of infiltration.

image

Figure 21.2 | Patterns of spread. T categories. The patterns of spread and the primary tumor classification are similarly color coded: Tis, yellow, cancer in situ of mucosa; T1, green (infiltrates the submucosa); T2, blue (penetrates to the muscularis propria); T3, purple (reaches the subserosa); and T4, red (invades through the serosa into a neighboring viscera). A. Coronal: Invasion into trachea and bronchi. B. Sagittal: Invasion into aorta. The concept of visualizing patterns of spread to appreciate the surrounding anatomy is well demonstrated by the six-directional pattern i.e. SIMLAP Table 21.2.

PATHOLOGY

The thoracic esophagus is largely a stratified squamous epithelium that gives rise to squamous cell carcinomas and is similar to the mucous membrane of the upper digestive passage, which has a rich network of submucosal lymphatics and capillary loops. The lower esophagus is prone to develop adenocarcinoma owing to Barrett epithelial islands of gastric mucosa (Fig. 21.1Table 21.1). This variety of cancer is presented separately, with digestive system cancers of the abdomen.

image

TNM STAGING CRITERIA

TNM STAGING CRITERIA

Esophageal staging has remained consistent with some changes in T and N categories. The only histologic difference from other hollow digestive system sites is the presence of an adventitia instead of a serosa. This allows for distensibility of the esophagus to accommodate a food bolus because, in its normal collapsed state, it appears on computed tomography (CT) to have a straw-like lumen of a few millimeters. T1 is mucosal, T2 muscular, T3 adventitial, and T4 is into the surrounding structures (Fig. 21.2).

SUMMARY OF CHANGES SEVENTH EDITION AJCC

• Tumor location is simplified, and esophagogastric junction and proximal 5 cm of stomach are included.

• Tis is redefined and T4 is subclassified into T4a resectable, T4b unresectable.

• Regional lymph nodes are redefined. N is subclassified according to the number of regional lymph nodes containing metastasis.

• M is redefined.

• There are separate stage groupings for squamous cell carcinoma and adenocarcinoma.

• Stage groupings are reassigned using T, N, M, and G classifications.

• Thoracic esophagus addressed the T-oncoanatomy of the mediastinum, and in turn emphasizes the importance of mediastinal lymph nodes (Fig. 21.3A). The more common neoplasms of the mediastinum include Hodgkin's (H) lymphoma, NH lymphomas. The esophageal tube is a hollow serial organ that encompasses the entire thorax, entering at the thoracic inlet and exits at the diaphragm. The T stage refers to depth of penetration of its wall:

• T1 submucosa

• T2 muscularis propria (externa)

• T3 adventitia

• T4 adjacent structures

• N stage criteria have changed and depend on node number.

• Stage groups are different with the four stage groups mushrooming into eight stage groups.

• Histopathology: Squamous cell cancer and adenocarcinoma each have their separate staging systems.

• Tumor grade and tumor location have been added, introducing more parameters into the staging system.

The TNM Staging Matrix is color coded for identification of Stage Group once T and N stages are determined (Table 21.3).

image

image

Figure 21.3A | The importance of early detection of esophageal cancer is noted in intramucosal and submucosal phases.

THORACIC ESOPHAGUS SQUAMOUS CELL

image

Figure 21.3 | TNM staging diagram. Esophageal cancers are the introduction to hollow organs with multilayered muscle walls lined by an epithelial mucosa on the inside and adventitia or serosa outside. Vertical presentation of stage groupings, which follow the same color code for cancer advancement, are organized in horizontal lanes: Stage 0, yellow; I, green; II, blue; III, purple; IVA, red; and metastatic stage IVB, black. Definitions of TN are on left and stage grouping is on the right. The histologic section of the esophageal wall illustrates the cancer invasion into and through the wall layers (Fig. 21.1). Note the nodal distribution is from the neck to the abdomen although the esophagus is a thoracic organ.

T-ONCOANATOMY

ORIENTATION OF THREE-PLANAR ONCOANATOMY

The isocenter chosen for the esophagus is at the thoracic T9/T10 level to signal the termination of primary sites in the thorax and simultaneously introduce the beginning of the digestive system. T9/T10 is the level of the esophageal opening in the diaphragm; T8 is for the level of the opening for the vena cava; and T12 is the stomal opening for the aorta (Fig. 21.4).

T-oncoanatomy

• Coronal: The T-oncoanatomy of the esophagus consists of three principal regions: cervical, thoracic, and cardiac portions (Fig. 21.5). The cervical esophagus extends from the pharyngeal–esophageal junction (the cricopharyngeal sphincter) inferiorly to the level of the thoracic inlet, about 18 cm from the upper incisor teeth. The upper and midthoracic esophagus extends from the thoracic inlet to a point 10 cm above the esophagogastric junction, which is usually at the level of the lower border of the esophagus to the cardiac orifice of the stomach, which is about 40 cm from the upper incisor teeth (Fig. 21.5A).

• Sagittal: The esophagus is a muscular tube consisting of two layers of smooth muscle, one longitudinal and the other horizontal, and this is carried through into the rest of the gastrointestinal system. Peristalsis is initiated with swallowing and the major function is to propel food into the stomach. There are two sphincters in the esophagus: the cricopharyngeal muscle and the cardiac sphincter at the cardia of the stomach. These sphincters have been extensively studied from the physiologic point of view and are common sites of both benign and neoplastic disease (Fig. 21.5B).

• Transverse: The esophageal opening of the diaphragm is anterior and to the left (T10) of the aorta (T12); note the esophagus in between the right and left layer of the mediastinum. The course of the esophagus is from slightly to the right of the midline to the left as it pierces the diaphragm through its own opening. It is in continual contact with the right lung; on the left side, the aorta is in continual contact with the left lung. The azygos vein provides a partial shield on the right side and posteriorly. Pulmonary veins are expected to be in more intimate contact because they drain to the left atrium, which is posterior to the ventricle. The thoracic duct is posterior to the esophagus along its course, which is the reverse of the esophagus coursing from the right side of midline to the left as it ascends. When the esophagus comes in front of the descending aorta, it is suspended by the mesoesophagus, which allows it to curve forward before its passes through the diaphragm (Fig. 21.5C).

image

Figure 21.4 | Orientation of T-oncoanatomy. The anatomic isocenter for three-planar oncoanatomy is placed in the midline and at the T9/T10 level at the dome of the diaphragm. A. Coronal. B. Sagittal.

image

Figure 21.5 | T-oncoanatomy. Connecting the dots: Structures are color coded for cancer stage progression. The Color Code for the anatomic sites correlates with the color code for the stage group (Figure 21.3B) and patterns of spread (Figure 21.2) and SIMLAP table (Table 21.2). Connecting the dots in similar colors will provide an appreciation for the 3D Oncoanatomy.

N-ONCOANATOMY AND M-ONCOANATOMY

N-ONCOANATOMY

The American Joint Committee on Cancer (AJCC)/International Union Against Cancer numbering of cervical mediastinal lymph nodes is consistent with IASLC lymph node map for lung cancers. Abdominal lymph nodes are numbered separately, and it differs from the International Anatomic Terminology.

The regional lymph nodes for the cervical esophagus are the cervical and supraclavicular nodes. For the thoracic esophagus, the regional nodes are the adjacent mediastinal lymph nodes. Non regional nodal involvement is considered distant metastasis. Retrograde and prograde lymphatic spread usually places all of the lymph node stations in the neck, mediastinum, and abdomen at risk. One of the major problems with control of this cancer is the frequency with which lymph node invasion occurs and the rapidity of its dissemination to the other distant anatomic areas. Esophageal cancer is therefore not only a disease of the chest, but also of the neck and abdomen. Because of its lymphatic drainage, esophageal cancer is a formidable tumor to encompass by locoregional modalities of therapy (Fig. 21.6Table 21.4).

Since the esophagus extends the entire vertical length of the thorax, the patterns of spread vary with the segment in which the cancer arises. Customarily the thoracic esophagus is divided into three segments: The upper third extends from the thoracic inlet to the level of the tracheal bifurcation; the middle third lies between the carina and 5 cm above the diaphragm; and the lower third includes the esophagogastric junction.

M-ONCOANATOMY

A rich plexus of venous anastomoses exists with stomach, liver, pancreas, and adrenals. Therefore, the liver, lung, and adrenals are the most common sites of distant metastases. Remote metastasis from the carcinoma of the esophagus, although ultimately fatal, often carries a better prognosis than when the primary lesion has extended locally outside the esophagus into mediastinal structures, a condition that is rapidly fatal.

image

image

Figure 21.6 | Orientation of N-oncoanatomy. A. Mediastinal sentinel nodes vary depending on location of cancer. Paracarinal and subcarinal nodes are frequently involved. B. The percentage of positive lymph nodes found at surgery for esophageal carcinoma in the upper, middle, and lower esophagus. (B: From Akiyama H, Tsurumaru M, Kawamura T. Principles of surgical treatment of carcinoma of the esophagus: Analysis of lymph node involvement. Ann Surg 1981;194(4):438–446, with permission.)

STAGING WORKUP

RULES FOR CLASSIFICATION AND STAGING

Clinical Staging and Imaging

The esophagus is inaccessible to physical examination, and endoscopy is limited as to depth of invasion. Imaging is critical to evaluation of staging (Table 21.5). Endoscopic ultrasound is of greatest value for superficial invasion of the muscular wall. CT provides the assessment of invasion into surrounding structures and regional lymph nodes in the mediastinum (Fig. 21.7). Metastatic disease in lung and liver can be examined with spiral CT at the same time. Magnetic resonance imaging (MRI) can be useful when invasion of mediastinal lymph nodes and structures is in doubt and needs to be resolved. Positron emission tomography (PET) can provide an overview if disseminated metastasis is suspected.

Pathologic Staging

All pathologic specimens from clinical invasive procedures—bronchoscopy, mediastinoscopy, mediastinotomy, thoracentesis, and thorascopy—are applicable. The thoracotomy and resection of primary and lymph nodes are the mainstay of pathologic staging. Preferably, six nodes should be examined.

Oncoimaging Annotations

• Ninety percent of adenocarcinomas occur near the esophagogastric junction.

• Double-contrast studies can recognize mucosal and submucosal lesions.

• CT, endoscopic ultrasound (EUS), and MRI provide a complete picture of invasion. EUS is more accurate in staging penetration of five esophageal layers in its walls, and CT is better for detection of invasion to adjacent structures.

• PET is better for finding metastases.

• EUS demonstrates hyperechoic alternately with hypoechoic layers of esophageal wall.

• MRI and Gd-DTPA shows extensions into mediastinal and diaphragmatic tissues.

• CT can assess the probability of aortic invasion by tumor invasion around aorta (i.e., 45% unlikely, 45% to 90% suspicious, more than 90% highly likely).

• Obliteration of small triangle of fat between aorta, esophagus, and spine predicts for aortic invasion.

image

PROGNOSIS AND CANCER SURVIVAL

• Tracheobronchial invasion is seen if the trachea's concave (inwardly bowed) appearance replaces convex (outwardly bowed).

• Pericardial thickening, pericardial effusion, and inward deformity are indicators of pericardial invasion.

• Lymph node invasion is suspected if lymph node is 1 cm in size but also for retrocrural nodes greater than or 6 mm, supraclavicular nodes greater than or 5 mm, and gastrohepatic nodes greater than or 8 mm.

PROGNOSIS

The limited number of prognostic factors are listed in Table 21.6.

image

Figure 21.7 | Axial CTs of T9 and T10 level correlate with the T-oncoanatomy transverse section (Fig. 21.5C). Oncoimaging with CT is commonly applied to staging cancers, often combined with PET to determine true extent of primary cancer and involved lymph nodes. Mediastinal window. 1, left ventricle; 2, papillary muscle; 3, right ventricle; 4, ventricular septum; 5, azygos vein; 6, hemiazygos vein; 7, esophagus.

CANCER STATISTICS AND SURVIVAL

The esophagus accounted for 16,640 new cancer cases and 15,475 cancer deaths (93%), with a 5-year survival rate improvement from 1950 to 2010 of 11%. Currently, relative 5-year survival for all stages is 14%, but when localized improves to 50% (Fig. 21.8).

image

Figure 21.8 | Five year survival for thoracic esophagus. (Data from Edge SB, Byrd DR, Compton CC, et al., AJCC Cancer Staging Manual, 7th edition. New York, Spinger, 2010.)

image

SECTION 3

Abdomen Primary Sites

image



If you find an error or have any questions, please email us at admin@doctorlib.info. Thank you!