Objective: To determine the risk of cancer before and after the diagnosis of motor neuron disease (MND), multiple sclerosis (MS), and Parkinson’s disease (PD).
Methods: Analysis of statistical database of linked statistical abstracts of hospital and mortality data in an area in southern England.
Results: Only people with PD showed a significant difference in the overall incidence of cancer compared to controls (rate ratio (RR) 0.76, 95 % confidence intervals 0.70-0.82 before PD; RR 0.61, 0.53-0.70, after PD). Rate ratios were close to one for cancer in patients after MND (0.98, 0.75-1.26) and after MS (0.96, 0.83-1.09). There were high rate ratios for malignant brain cancer (RR 7.4, 2.4-17.5) and Hodgkin’s lymphoma (5.3, 1.1-15.6) in patients diagnosed with MND after cancer. In people with MS, malignant brain cancer also showed an increased rate ratio both before hospital admission with a diagnosis of MS (RR 3.2, 1.1-7.6) and after (RR 2.4, 1.2-4.5). In people with PD, several specific cancers showed significantly and substantially reduced rate ratios for cancer, notably smoking-related cancers including lung cancer (RR 0.5, 0.4-0.7, before PD; 0.5, 0.4-0.8, after PD) but also cancers that are not strongly smoking-related including colon cancer (RR 0.7, 0.6-0.9, before PD; 0.5, 0.4-0.8, after PD).
Conclusions: People with MND, or MS, do not have an altered risk of cancer overall. There may sometimes be misdiagnosis between MND or MS and brain tumours. PD carries a reduced risk of cancer overall, of some smoking-related cancers, and of some cancers that are not smoking-related.