Esophageal cancer5111214 Epidemiology

More than 99 percent of esophageal tumors are of the malignant variety. However, esophageal cancer is relatively uncommon in the United States, with an annual rate of less than 10 per 100,000. Most are diagnosed between the sixth and the eighth decade of life, and, in general, men are two to four times more likely to be afflicted than females. Nevertheless, it is a lethal problem— once diagnosed, the overall 5-year survival rate is typically less than 10 percent,

Figure 8-6 The characteristic radiographic finding of an esophageal leiomyoma on barium esophagogram, showing a smooth concave filling defect, created by a well-defined lesion, with sharp, intact mucosal shadow with abrupt angle where the tumor meets the normal esophageal wall. (Source: Courtesy of William Thompson, M.D., and Anamaria Gaca, M.D., Department of Radiology, Duke University Medical Center.)

Figure 8-6 The characteristic radiographic finding of an esophageal leiomyoma on barium esophagogram, showing a smooth concave filling defect, created by a well-defined lesion, with sharp, intact mucosal shadow with abrupt angle where the tumor meets the normal esophageal wall. (Source: Courtesy of William Thompson, M.D., and Anamaria Gaca, M.D., Department of Radiology, Duke University Medical Center.)

and it is responsible for approximately 10,000-12,000 deaths per year in the United States. Internationally, esophageal cancer is much more prevalent, accounting for greater than 300,000 new cases per year. It is endemic in certain parts of the world. For example, in northeast Iran and in parts of northern

China, there are well over 100 new cases per 100,000 population each year. Furthermore, esophageal cancer has also been consistently one of the top 10 leading causes of cancer deaths worldwide.

Etiologic and Risk Factors

Based on epidemiologic studies, alcohol and tobacco use are strongly associated with esophageal cancer; individuals having a strong history of using both of these substances are 25-100 times more likely to develop esophageal cancer. Also implicated as causative factors are nitrosamines, foods contaminated by fungi and yeast that produce mutagens, ingestion of hot beverages causing chronic irritation of the esophageal mucosa, betel leaf, slaked lime, and resin from the acacia. Premalignant esophageal conditions include acha-lasia, reflux and radiation esophagitis, Barrett esophagus, caustic burns, Plummer-Vinson syndrome, leukoplakia, esophageal diverticula, and familial keratosis palmaris et plantaris (tylosis).

Histologic Cell Types

Although malignant esophageal tumors can be any one of several histologic cell types, including anaplastic small cell or oat cell carcinoma, adenoid cystic carcinoma, malignant melanoma, and carcinosarcoma, the most common cell types are squamous cell carcinoma and adenocarcinoma.

Squamous Cell Carcinoma

Worldwide, squamous cell carcinoma represents approximately 95 percent of all esophageal cancers. Squamous cell carcinoma is a malignant tumor of the epithelial type, and it originates from the mucosa of the esophagus. Most cases of squamous cell esophageal cancer are in stage III or IV at the time of diagnosis. Squamous cell carcinomas typically occur in the upper and middle third of the esophagus, although in about 30 percent of patients, they are found in the distal third. There are four gross pathologic growth patterns: fungating, ulcerating, infiltrating, and polypoid. The fungating squamous cell carcinoma is the most common, representing about 60 percent of esophageal cancer of the squamous cell type; the polypoid variety is the least common (less than 5 percent of the cases), but it is associated with the best 5-year survival rate (about 70 percent).

Adenocarcinoma

The incidence of adenocarcinoma has dramatically increased recently, especially in industrialized countries. In fact, adenocarcinoma has now surpassed squamous cell carcinoma as the most common type of esophageal cancer in the United States. Unlike squamous cell carcinoma, adenocarcinoma afflicts Whites 4 times more frequently than Blacks; male are affected more than female. Adenocarcinoma typically occurs in the distal third of the esophagus, and it originates from submucosal glands or from columnar epithelium that is heterotopically located or has formed from metaplastic degeneration. Esophagus with columnar-type epithelium that has replaced the normally present squamous cell epithelium is called Barrett esophagus. Three different types of columnar epithelium can be found in Barrett esophagus—specialized intestinal metaplasia, gastric fundic type, and junctional type—of which specialized intestinal metaplasia is the most frequently seen as well as the most strongly associated with dysplasia and carcinoma in Barrett esophagus. The malignant cells of adenocarcinoma, as compared to normal cells from which they originated, have a characteristic reduced cyto-plasmic-to-nuclear ratio. Individuals with Barrett esophagus are 40 times more at risk for developing esophageal adenocarcinoma than the general population; it is estimated that adenocarcinoma arises from 8 to 15 percent of patients with Barrett esophagus. The finding of dysplasia in Barrett mucosa is essentially synonymous with carcinoma in situ and is an indication for surgical resection.

Definition and Clinical Presentations

Patients with esophageal cancer may initially present with nonspecific retrosternal discomfort and indigestion. With time, progressive dysphagia is the chief complaint, occurring in 80-95 percent of patients who eventually are diagnosed with esophageal cancer. Weight loss ensues as a result of poor nutritional intake due to dysphagia or odynophagia, or as a consequence of metastatic spread of the malignancy. Other symptoms and signs include hematemesis, when the mucosal surface of the tumor becomes ulcerated, and coughing or hoarseness, especially when the tumor involves the cervical esophagus.

Diagnostic Tests

Plain radiographs will sometimes provide nonspecific clues, such as abnormal azygoesophageal recess, mediastinal widening, posterior tracheal indentation, that might suggest the presence of esophageal tumor. Barium esophagogram, which should be ordered in anyone with the complaint of dysphagia, is helpful in determining the size, the extent, and the location of the tumor and in demonstrating the presence of any obstruction or fistulas. Today, endoscopy with biopsy is the gold standard in confirming the presence of the malignancy and establishing a tissue diagnosis; often, it is the method by which carcinoma in situ or early stage cancer is detected through routine surveillance in patients with high-risk factors. A CT scan is done to evaluate any possible involvement of regional lymph nodes and any distant metastases. Positron emission tomography (PET) imaging, using fluorodeoxyglucose (FDG) that is preferentially taken up by malignant cells, can be used in supplementing the information obtained from CT scan and other studies; the advantage of PET imaging is the superior sensitivity for detecting distant metastases. Endoscopic ultrasound (EUS) is a technology that has been popularized recently because of its ability to more accurately assess both the depth of tumor invasion (T status) and the status of periesophageal lymph nodes. The accuracy of T stage determination by EUS has been shown to be between 60 and 90 percent.

Staging

Once the diagnosis of esophageal cancer is made by barium esopha-gogram and esophagoscopy, establishing the stage of the cancer is important in deciding the appropriate therapeutic options. Clinical staging can be accomplished based on many of the diagnostic studies (e.g., CT scan, PET imaging, and/or EUS) mentioned earlier; determining the pathologic staging will have to wait until a surgical specimen is available. The staging system most commonly used worldwide is the TNM format devised by the American Joint Committee on Cancer (AJCC) (Table 8-2).5 T indicates the level of primary tumor invasion into the esophageal wall; N denotes the absence or presence of regional lymph node involvement; and M indicates whether there is distant metastasis or not. The overall 5-year survival rate is approximately 5 percent for esophageal cancer; based on the staging system, the

5-year survival rate is 50-55 percent for stage I, 15-38 percent for stage II,

6-17 percent for stage III, and less than 5 percent for stage IV.

Treatment

Despite the advances in surgery, chemotherapy, and radiation therapy, there has been little success in consistently achieving long-term survival for patients with esophageal cancer. Much of this might be due to the limitation of early detection of esophageal cancer. This is evidenced by the fact that more than three quarters of the patients who underwent surgical resection already have stage III or IV cancer. Furthermore, when a curative resection is documented, the 5-year survival rate is still only 30 percent. Therefore, the primary goal of any treatment is to provide symptomatic relief, most frequently from dysphagia, and at least to restore the patient's ability to comfortably swallow liquids.

The methods of palliative treatment include dilatation, stenting, photo-dynamic therapy, external-beam and intracavitary radiation therapy, and endoscopic laser therapy. The average length of survival with any of these palliative measures is less than 6 months. Palliative surgery using colon interposition or reversed gastric tube to bypass unresected esophagus have been used and are associated with at least a 25 percent operative mortality and a survival that averages only 6 months.

In patients with localized esophageal cancer, a more definitive operation provides the best chance of long-term survival. Three general approaches are available. First, a left thoracoabdominal approach (Sweet operation) can be used for distal esophageal tumors (Fig. 8-7). This operation allows the best

Table 8-2 The TNM Staging System Devised by the AJCC

Definition of TNM

Primary tumor (T)
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