Ingested asbestos in filtered beer, in addition to occupational exposure, as a causative factor in oesophageal adenocarcinoma

Oesophageal adenocarcinoma has become much more common over the past 50 years, particularly in Britain, with an unexplained male to female ratio of > 4:1. Given the use of asbestos filtration in commercial brewing and reports of its unregulated use in British public houses in the 1970’s to clear draught beer “slops”, we have assessed the hypothesis that ingested asbestos could be a causative factor for this increased incidence. Importantly, occupational asbestos exposure increases the risk of adenocarcinoma but not squamous cell carcinoma of the oesophagus. The presence of asbestos fibres was consistently reported in filtered beverages including beers in the 1970s and asbestos bodies have been found in gastrointestinal tissue, particularly oesophageal tissue, at autopsy. There is no reported association between the intake of alcohol and oesophageal adenocarcinoma but studies would mostly have missed exposure from draught beer before 1980. Oesophageal adenocarcinoma has some molecular similarities to pleural mesothelioma, a condition that is largely due to inhalation of asbestos fibres, including predominant loss of tumour suppressor genes rather than an increase of classical oncogenic drivers. Trends in incidence of oesophageal adenocarcinoma and mesothelioma are similar, rising rapidly over the past 50 years but now plateauing. Asbestos ingestion, either from beer consumed before around 1980, or from occupational exposure, seems a plausible causative factor for oesophageal adenocarcinoma. If this is indeed the case, its incidence should fall back to a low baseline by around 2050.