Esophageal cancer is a neoplasm of tissues lining the esophagus. Histologically, this neoplasm may be of two types: squamous cell carcinoma that begins in the flat cells lining the esophagus, and adenocarcinoma which begins with the esophageal secretory cells. In its initial stages, esophageal cancer may not present with any serious symptoms, thereby delaying its diagnosis. In later stages, affected patients may present with pain while swallowing, a feeling of food getting stuck in the throat, weight loss, and chronic cough with occasional coughing up of blood. Since most of these symptoms are general in nature, and could be a part of many other conditions, correct diagnosis assumes great importance. Most people affected with esophageal cancer are diagnosed in their fifth to seventh decades of life. The condition is also more prevalent among people of African origin than among Caucasians. Squamous cell carcinoma is seen to be more frequent in people who smoke or chew tobacco, consume alcohol, are infected with human papilloma virus, have chronic scarring of the esophagus due to some previous injury, or suffer from a genetic condition called tylosis. On the other hand, people who are affected with Barett's Esophagus, a condition characterized by intestinal metaplasia towards the esophagus, are at an increased risk for developing adenocarcinoma of the esophagus.
First step in the diagnosis of esophageal cancer is usually an X-ray analysis. Barium swallow as well as endoscopy are also used to further support the diagnosis. Confirmation of the condition usually involves a biopsy of esophageal tissue collected through endoscopy. Since this form of carcinoma has a high rate of malignancy, physicians may also check for any spread of the cancer. This is usually performed through a CAT scan or a bone scan. As in most other neoplasms, treatment is either in the form of surgery, where a part of the esophagus is removed, radiation therapy, chemotherapy, laser therapy, or electrocoagulation. Prognosis depends upon the stage at which the cancer is diagnosed. Of those diagnosed at the earliest stage, about 80-90% have a 5-year survival rate. Unfortunately, there are no early detection tests for the condition. However, people at high risk, such as those affected with Barett's Esophagus are advised to regularly check themselves up for any neoplastic tissue changes.
As in most cancers, several tumor suppressor and anti-apoptotic genes have been implicated in the genetics of esophageal cancer. These genes include TP53 (Tumor Protein 53), TP15, TP16, Cyclin D1, and BCL-2. Polymorphisms in both ALDH2 (Aldehyde Dehydrogenase 2) gene that are common in certain Asian populations have been shown to confer an increased risk to the development of esophageal cancer. In addition, a locus on chromosome 17q25 has been found to be associated with tylosis related esophageal cancer.