Diet, obesity and reflux in the etiology of adenocarcinomas of the esophagus and gastric cardia in humans.

Incidence rates for esophageal adenocarcinoma have increased >350% since the mid-1970s. Rates for gastric cardia adenocarcinoma have also increased, although less steeply. This led to the initiation of large population-based case-control studies, particularly in the United States and Sweden, aimed at identifying risk factors for these cancers. Results have been emerging from these studies, with the consistent finding that obesity and gastroesophageal reflux disease are important risk factors for these cancers. Analyses of dietary factors are also available and indicate that diets high in total fat, saturated fat and cholesterol are associated with an increased risk of these cancers, whereas several nutrients, particularly those found in plant foods (fiber, vitamin C, beta-carotene, folate), are associated with a reduced risk. Considering the incidence trends of these cancers and the trends in the prevalence of risk factors, the increasing prevalence of obesity in the United States likely accounts for some of the increased incidence. However, other contributors to the increasing trends have been suggested and will be discussed. Because diet, obesity and gastroesophageal reflux disease may not act independently in contributing to these cancers, current research is attempting to identify associations between the three risk factors and potential mechanisms of action to better understand the etiology of these cancers.