Anorexia is a common and well-known symptom of many types of cancer, but what about the risk of cancer among patients with an eating disorder? Previous studies have focused on the hypothesis that patients with anorexia nervosa might be at lower risk of cancer overall due to energy restriction. [1, 2]
However, a recent CSO-funded study in Scotland has shown that patients who have been admitted to hospital with an eating disorder in the past, are at higher risk of oesophageal cancer subsequently.  Although there have been case reports of oesophageal cancer occurring in patients with a history of eating disorder, this cohort study is the first
to report an increased risk of oesophageal cancer that is statistically significant.
The research team from NHS National Services Scotland and the University of Edinburgh followed up 3,617 patients who had been admitted to Scottish hospitals with an eating disorder between 1981 and 2011. The risk of oesophageal cancer was increased 6-fold in the study cohort, although all of the cases occurred in women with a history of anorexia nervosa.
Established risk factors for oesophageal cancer (alcohol, smoking, and nutritional deficiency) may be the most likely explanation, because the study cohort had higher than average rates of admission to hospital with alcohol-related conditions and chronic obstructive pulmonary disease (which is often associated with smoking). Although some people with eating disorders practice self-induced vomiting to control their weight, acid damage to the lining of the oesophagus seems a less likely explanation because none of the cases of oesophageal cancer were of the glandular subtype (adenocarcinoma), which has typically been associated with regurgitation of stomach acid in other studies.
Although these findings are interesting, it is important to note that the study was observational in nature, and quite limited in size. It will be important to see the results confirmed in other, larger studies, with longer follow-up.
Closely following publication of the Scottish study, a study from Sweden, Denmark and Finland has just been published, and the findings for oesophageal cancer are largely consistent with the results of the Scottish study.  The research team from the Nordic countries found a 5-fold increased risk of oesophageal cancer in women with anorexia nervosa compared to randomly selected comparisons. Taken together, these studies suggest that there may be a place for targeted health promotion, as well as maintaining a low threshold for investigation of symptoms suggestive of oesophageal cancer in patients with a history of anorexia nervosa.
Paradoxically, obesity is also associated with an increased risk of oesophageal cancer (adenocarcinoma). WCRF estimate that 31% of adenocarcinoma is related to body fatness.
The Scottish study reported in this article was supported by a grant from the Chief Scientist Office, Scottish Government (Grant number CZH/4/980).