Barrett's esophagus and esophageal adenocarcinoma

Esophageal and gastric cardia adenocarcinomas have recently been the most rapidly increasing cancers in the United States. Effective cancer control decreases incidence by identifying and altering underlying risk factors, employs new agents to minimize cancer risk, and develops means of identifying earlier, more curable cancers through screening/surveillance.; This dissertation describes a series of four studies evaluating these factors. The first study evaluated the global incidence of disease, and evaluated whether esophageal adenocarcinoma and gastric cardia adenocarcinomas have similar disease distributions. It found marked disparities in cancer incidence between countries, suggesting that environmental factors substantially influence disease incidence. It also found differences in incidence distribution between esophageal adenocarcinoma and gastric cardia adenocarcinoma, indicating these cancers may have different risk factors. Second, endoscopic surveillance of esophageal adenocarcinoma's malignant precursor, Barrett's esophagus, is frequently performed to identify earlier, more treatable cancers; however, little data exists to support this practice. The second study evaluated whether, among patients with esophageal adenocarcinoma and known pre-existing Barrett's esophagus, performance of endoscopic surveillance was associated with improved survival after cancer diagnosis. It found surveillance was strongly associated with survival, with a 73% five-year survival rate among patients in surveillance vs. a 0% five-year survival rate among patients not in surveillance. The third study evaluated the literature for potential new agents effective at decreasing cancer incidence. This study performed a systematic review and meta-analysis of the association between aspirin or non-steroidal anti-inflammatory medication ingestion and esophageal cancer. This study found a protective relationship between aspirin/NSAID ingestion and esophageal cancer, a protective association for both esophageal adenocarcinoma and squamous cell carcinoma, and evidence of a dose effect. The final study evaluated the association between a potential risk factor (calcium channel blocker use) and Barrett's esophagus using pharmacy records from a health maintenance organization and a mailed questionnaire. This investigation found no association between calcium channel blocker use and Barrett's esophagus.; Combined, these studies substantially extend existing knowledge regarding the distribution of, risk factors for, potential agents for prevention of, and surveillance of esophageal adenocarcinoma and its premalignant precursor, Barrett's esophagus. They also raise several additional questions for future investigations.