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A large number of different tumors can involve the esophagus ( Table 5). The vast majority are extremely rare and often do not produce clinical disease. Unfortunately, the most common esophageal neoplasm is squamous cell carcinoma, which has a five-year survival rate (< 10%) that is among the lowest for any neoplastic disease.TABLE 5. Classification of esophageal tumors Benign tumors Malignant tumors Tumor-like lesions
Leiomyoma
is the most common benign esophageal tumor. Esophageal leiomyomas may
produce dysphagia and retrosternal chest pain, but in most cases are
asymptomatic. Unlike gastric leiomyomas, they rarely hemorrhage. On
barium x-ray a characteristic smooth, round luminal defect is seen
projecting from one wall. Its endoscopic appearance is a clearly
demarcated projection into the lumen; the overlying mucosa is normal.
Endoscopic biopsy is not helpful, as the lesion is submucosal and
cannot be reached with biopsy forceps. If leiomyomas are symptomatic,
surgical enucleation is indicated.
Squamous cell papillomas consist of
frond-like projections of the lamina propria that are covered by
squamous epithelium and develop at several sites simultaneously. They
rarely grow large enough to produce dysphagia. They occur in
association with acanthosis nigricans and tylosis. Except when
associated with tylosis, these lesions are not considered to be
precursors of squamous cell carcinoma. Fibrovascular polyps consist of a core of loose fibrous connective tissue, fat and blood vessels covered by a thick layer of squamous epithelium. Such a polyp may become quite large, with a very long stalk that permits the lesions to flop back and forth in the esophageal lumen. Patients with this lesion have presented with regurgitation of the free end of the polyp into the mouth; in other instances, the regurgitated polyp has caused sudden death by obstructing the larynx. Granular cell tumors are submucosal lesions with intact mucosal covering that are usually picked up incidentally at endoscopy. They may originate from neural elements. They rarely cause symptoms, although there have been occasional reports of dysphagia due to large granular cell tumors. There have also been rare reports of malignant granular cell tumors in the esophagus. Symptomatic tumors need to be removed surgically.
Carcinoma of the esophagus is a relatively uncommon malignancy in Canada, with only 3 to 4 new cases per 100,000 population per year in males and just over 1 new case per 100,000 population per year in females. Nevertheless, because of its poor prognosis, esophageal cancer ranks among the 10 leading causes of cancer death in Canadian men 45 years of age and older. Although several different types of primary and secondary malignancies can involve the esophagus (Table 5), squamous cell carcinoma and adenocarcinoma are by far the most common esophageal malignancies.
Adenocarcinoma used to make up approximately 10% of all esophageal cancers. However, its incidence has been increasing in recent decades such that now it comprises up to 30-40% of esophageal cancers in North America. Rarely, primary esophageal adenocarcinomas arise from embryonic remnants of columnar epithelium or from superficial or deep glandular epithelium. In most instances, adenocarcinoma arises from metaplastic Barrett's epithelium in the distal esophagus. Adenocarcinoma of the cardia of the stomach may also involve the distal esophagus and give the appearance that the cancer arises from the esophagus. The true incidence of Barrett's-related cancer is uncertain, but most studies suggest that patients with Barrett's esophagus will develop adenocarcinoma at a rate of about 0.5% per year. This is a significant problem given the large number of reflux patients with Barrett's metaplasia. Because dysplasia develops prior to frank carcinoma in Barrett's epithelium, most experts suggest that these patients should undergo surveillance endoscopy with multiple biopsies every one to two years to identify those who are likely to progress to cancer (Section 7). The clinical presentation and diagnostic evaluation of patients with adenocarcinoma of the esophagus are similar to squamous cell carcinoma (Section 12.2.2). These lesions are not radiosensitive and their response to various chemotherapeutic agents is not very satisfactory. Surgical resection or palliation with laser, photodynamic therapy, peroral dilation and/or stent placement are the preferred treatments. The prognosis is similar to that for gastric adenocarcinoma - i.e., an overall five-year survival rate of < 10%.
The occurrence of squamous cell carcinoma of the esophagus shows striking geographic variability, with high frequencies in certain regions of Iran, Africa, China and the former USSR. This has led to several theories concerning certain environmental agents that may be important etiologically (Table 6). In North America, squamous cell carcinoma is associated with alcohol ingestion, tobacco use and lower socioeconomic status. It is also significantly more common in blacks and in males. Characteristically these cancers extend microscopically in the submucosa for substantial distances above and below the area of the gross involvement. They also have a propensity to extend through the esophageal wall and to regional lymphatics quite early. Furthermore, they usually produce symptoms only when they have become locally quite advanced. For these reasons approximately 95% of these cancers are diagnosed at a time when surgical cure is impossible. In most studies, the mid-esophagus is the most common site of origin; however, others have reported distal cancers to be most common. The lungs and liver are the most common sites of distant metastases. Most patients present with progressive, predictable dysphagia and weight loss. Other symptoms include odynophagia, chest pain (which may radiate to the mid-scapular region), hoarseness (due to recurrent laryngeal nerve involvement) and blood loss. Pulmonary complications due to either direct aspiration or esophagorespiratory fistulas are also quite common during the course of the disease. Physical examination is usually negative aside from signs of weight loss. Hepatomegaly or enlarged cervical or supraclavicular lymph nodes may be detected in cases of disseminated metastases. Barium swallow is usually diagnostic, although small cancers can be missed in up to 30% of cases. Endoscopy with multiple directed biopsies combined with brush cytology is required to confirm the diagnosis. This should be followed by careful attempts to stage the disease prior to deciding on therapeutic intervention. In addition to a careful physical examination, chest x-ray and blood tests for transaminases, alkaline phosphatase and bilirubin, an ultrasound of the abdomen should be performed to look for liver metastasis. If this is negative, one should proceed to a CT scan of the thorax in order to define the extent of local spread. Unfortunately the CT scan lacks sensitivity in this regard. Endoscopic ultrasound appears promising in accurately assessing depth of tumor involvement and presence or absence of enlarged mediastinal lymph nodes. If the above investigations are negative, some experts recommend bronchoscopy, mediastinoscopy and scalene node biopsy prior to attempting surgical resection. Treatment results of squamous cell carcinoma of the esophagus are discouraging. Although it is traditionally taught that surgical resection is the only chance for a cure, there is no convincing evidence that "curative" surgery is better than "curative" radiotherapy. These tumors are quite radiosensitive; however, most centers give radiotherapy to patients who have advanced unresectable tumors or other health problems that make them poor surgical candidates. This understandably leads to very poor overall survival following radiotherapy. In the few reports where radiotherapy is used as the primary mode of therapy in patients who might otherwise be considered surgical candidates, the five-year survival rate is as high as 17%, which compares quite favorably to surgical results. Both forms of treatment have significant morbidity, and the mortality following esophageal resection is at least 10%. Controlled trials are needed, but in only a small proportion of the total population of esophageal cancer patients is cure a realistic goal. In the majority the disease is too far advanced. New regimens that combine radiotherapy and chemotherapy, with or without surgery, are currently being evaluated. The goal of treatment has to be palliation in most patients. Both radiotherapy and modified surgery can be used in this setting; however, other modalities are often necessary. The dysphagia can be relieved with peroral dilation, but in many patients this becomes exceedingly difficult as the disease progresses. If this is the case, a prosthetic device can sometimes be placed across the tumor to maintain luminal patency. These stents can work quite well, although tube blockage, tube migration and erosion through the esophageal wall are important complications. These prosthetic devices are the best treatment for an esophagorespiratory fistula. Endoscopic Nd-YAG laser therapy has been used to destroy tumors that obstruct the esophageal lumen. This appears to be a very useful form of palliation, but it is expensive and has not as yet been documented to be superior to dilation and stent placement. Photodynamic therapy has recently been approved for palliation of neoplastic dysphagia. This involves using a photosensitizing compound that accumulates in cancer cells, which leads to their destruction when they are exposed to light of a certain wavelength. The caring physician must also provide emotional support, nutritional support and adequate pain therapy for these unfortunate patients. TABLE 6. Esophageal squamous cell carcinoma: possible etiological factors Alcohol |
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