Obesity and Oesophageal Cancer.

A substantial increase in the incidence of oesophageal adenocarcinoma has been observed in Western countries during the past 30 years, which may be related to the parallel rise of the obesity prevalence. On the other hand, incidence rates of oesophageal squamous cell carcinomas, the other major histological type of oesophageal cancer, have remained relatively stable. Epidemiological research of the past decades has identified obesity as risk factor for oesophageal adenocarcinoma. Studies investigating general obesity as assessed by body mass index (BMI) provide evidence for a strong positive association with oesophageal adenocarcinoma. Studies investigating abdominal obesity in relation to oesophageal adenocarcinoma observed also positive associations, which may be independent of general obesity. Some studies indicate that early life obesity is also associated with higher risk of oesophageal adenocarcinoma, but it is as to date unclear whether these associations are independent of adult obesity. Part of the positive association between obesity and oesophageal adenocarcinoma may be explained through obesity-related mechanical promotion of gastroesophageal reflux disease, which is one of the main risk factors for oesophageal adenocarcinoma. Other lines of evidence point to an independent role of metabolic pathways modulating cell proliferation, apoptosis and cell growth such as pro-inflammatory cytokines, adipokines and insulin resistance, the role of which in oesophageal carcinogenesis is, however, as to date insufficiently understood. Studies investigating obesity in relation to squamous cell carcinoma observed inverse relationships, but the underlying mechanisms remain unclear.