Swiss researchers say so
Researchers working at the University of Basel conducted a retrospective study on a large number of subjects using the research database of UK GPs (UK General Practice Research Database). They compared the diagnoses of cancer between the patients diagnosed with Parkinson’s disease between 1994 and 2005 and a similar sample of subjects who did not have the disease. The risk of cancer was 23% lower in patients with Parkinson’s disease. In particular, the risk of a malignant tumor related to smoking, such as lung or bladder carcinoma, was 53% lower and the risk of hematological malignancy was 68% lower. The only exception was melanoma.
Source: Becker C et al Parkinsonism Relat Disord online 27 november 2009