Anti-p53 antibodies in patients with Barrett's esophagus or esophageal carcinoma can predate cancer diagnosis

Barrett's esophagus

Intestinal metaplasia in Barrett's esophagus is a major risk factor for esophageal adenocarcinoma, a tumor whose incidence rate has more than tripled in the United States over the past 2 decades. Studies have identified a number of molecular abnormalities that may be involved in the progression from dysplasia to cancer in Barrett's esophagus, including altered expression of cadherins and catenins; inactivation of tumor-suppressor genes, such as p53, p21, p27, and p16; and increased activity of the enzymes cyclooxygenase-2 and inducible nitric oxide synthase. Studies on the role of Helicobacter pylori in the pathogenesis of intestinal metaplasia at the gastroesophageal junction have yielded contradictory results. It appears, however, that gastric infection with strains of H. pylori containing a cagA gene associated with cytotoxin expression may protect against the development of dysplasia and adenocarcinoma in Barrett's esophagus. The role of ablation therapy for Barrett's esophagus remains controversial, largely because thermal and photochemical ablative techniques often leave foci of intestinal metaplasia behind.

Esophageal cancer

Carcinoma of the esophagus and gastroesophageal junction continues to be an aggressive cancer with poor prognosis, despite improved surgical results and the potential benefit of combined multimodality regimens. Additional data seem to confirm the rising incidence of adenocarcinoma, although users of nonsteroidal anti-inflammatory drugs seem to have a decreased risk. Much attention is focused on detecting high-grade dysplasia and early carcinoma with promising results using red fluorescence after preceding 5-aminolevulinic acid (ALA) sensitization. Positron emission tomography made a major breakthrough and seems to be superior to computed tomography in detecting distant metastasis as well as lymph node metastasis. Endoscopic ablation of early carcinoma results in promising early results, but a major issue remains the EUS discrimination between Tis-T1a and T1b, as the latter is frequently associated with lymph node metastasis. In the field of molecular biology, research is unraveling the role of cadherins and catenins in the mechanism underlying cell adherence, cell movement, and progress toward tumor formation. Mutations of p53 are correlated with loss of apoptosis and form an early step in progress toward carcinoma as well as mutations of other tumor-suppressing genes (eg, p16 and Rb mutations). Detection of such mutations may become useful prognostic indicators, but illustrate the genetic polymorphism influencing the susceptibility to carcinoma. Several lines of evidence suggest that the stabilizing or overriding of p53 mutant cancer cells and restoration of the wild-type tumor suppressor gene p53 may improve results of DNA damaging treatment modalities. Further research in this field may lead to new forms of anticancer therapy.

Barrett's Esophagus and Barrett's Associated Neoplasia: Etiology and Pathologic Features

BACKGROUND: The incidence of Barrett's esophagus (BE) has been increasing in recent years. Patients with BE have 30- to 125-fold increased risk of developing adenocarcinoma. New techniques allowing early diagnosis, in addition to the identification of markers capable of predicting tumor progression, are needed. METHODS: The authors discuss the diagnostic features of BE and BE-associated neoplasia. RESULTS: BE can exhibit different types of metaplastic mucosa, but only the specialized (intestinal) mucosa has the potential to progress to dysplasia and carcinoma. The problems associated with diagnosing BE and with predicting the behavior of this condition are outlined. CONCLUSIONS: Studies are underway to identify molecular markers capable of predicting which BE patient will progress to carcinoma. Brush cytology and flow cytometry may become useful tools in the early detection of this disease.