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Increased prevalence of malignant melanoma and skin carcinoma before the diagnosis of Parkinson disease
A large follow-up study in Denmark showed a two-fold higher incidence of malignant melanoma in patients with diagnosis of Parkinson disease than in the general population. In a population-based case-control study, we investigated the prevalence of malignant melanoma and other cancers before a first hospitalization or out-patient visit for Parkinson disease. We used the National Danish Hospital Register to identify 8090 patients with a primary diagnosis of Parkinson disease. Each case was matched with 4 population controls selected at random from among inhabitants alive at the date of first hospital contact with the patient. Incident cases of cancer since 1943 were ascertained by linkage to the Danish Cancer Registry, and cancer histories of patients with Parkinson disease were compared with those of population controls. We observed an increased prevalence of malignant melanoma and skin carcinoma prior to the first hospital contact for Parkinson disease, with overall odds ratios of 1.44 (95% confidence interval, 1.03-2.01) and 1.26 (1.11-1.43), respectively. To the contrary, we observed a reduced prevalence of cancers of smoking-related sites in patients before their first hospital contact for Parkinson disease. In conclusion, the findings of an increased prevalence of
malignant melanoma and skin carcinoma before the diagnosis of Parkinson
disease weakens the hypothesis that these cancers are caused by therapy of Parkinson
disease. Our finding of a decreased prevalence of
smoking-related cancers preceding Parkinson disease is consistent with the
well-known higher risk of Parkinson disease among non-smokers.
Bibliographic reference:
Jørgen H. Olsen Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark
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