Oesophageal adenocarcinoma: the new epidemic in men?
ABSTRACT The last decades have witnessed an unprecedented rise in the incidence of oesophageal adenocarcinoma. This rise has mainly affected men, and current male-to-female sex ratio estimates range from 7-10 to 1. Major risk factors for oesophageal adenocarcinoma are gastro-oesophageal reflux disease and obesity, especially in combination. The prevalence of these risk factors has increased during the last decades, but there does not seem to be a marked differential distribution among men and women. However, reflux among men is more often associated with erosive reflux disease than it is among women. There is also evidence that male-type obesity, with a prominent abdominal distribution of fat, confers a greater risk increase for oesophageal adenocarcinoma than the female equivalent. Due to the marked male predominance and the finding that women tend to develop specialized intestinal metaplasia (Barrett's oesophagus) and adenocarcinoma at a later age than men, interest has been directed towards a potential aetiological role of reproductive factors and sex hormones. Breastfeeding has been found to be a protective factor for the development of adenocarcinoma, while no association has hitherto been established with other reproductive factors. Taken together, the male predominance in the incidence of oesophageal adenocarcinoma may partly be explained by the differential effect of the major risk factors reflux disease and obesity, but the mechanisms whereby this occurs need to be elucidated. Moreover, the association with breastfeeding indicates a need for extensive epidemiological studies to clarify a possible role of sex hormonal influence in the aetiology of oesophageal adenocarcinoma.