Background A number of epidemiologic studies show a decreased risk of non-melanoma cancer in Parkinson's disease (PD). Cigarette smoking is less prevalent in PD and hence the risk of smoking related neoplasia such as lung and colon would be expected to be decreased in PD. A link is shown between decreased physical activity and colorectal cancer. Increased dietary intake of iron increases colorectal cancer risk and iron deposition in the basal ganglia is a feature of PD. Thus common mechanisms may be involved in both disorders. Our study looks at a cohort of surgically treated PD patients to see if there is an altered risk of colorectal cancer among them.

Method In our population of patients fitted with a deep brain stimulator between 2002 and 2010, we searched for causes of death confirmed against death certificates and a histological diagnosis of colorectal cancer in the patient records.

Results Of 22 patients who had died, 3 had a diagnosis colorectal cancer. 1 more died of a carcinoembryonic antigen positive cancer of unknown origin.

Discussion From UK national statistics, colorectal cancer accounts for between 2.7 and 3.2% of all deaths. Although the small number of deaths in our cohort requires careful interpretation of the results, 14% of our cohort having a diagnosis of colorectal cancer suggests that the lifetime risk of colorectal cancer is not reduced in PD patients. This observation merits further investigation in a larger cohort of PD patients.