CHICAGO — The results of prospective screening for skin lesions in patients who have Parkinson's disease have suggested that melanoma may occur at a significantly higher rate in these patients, Dr. John M. Bertoni reported at the annual meeting of the American Neurological Association.
Previous reports have suggested an association between melanoma and Parkinson's disease, but all have been retrospective. The use of levodopa has been associated with melanoma in case series, but no controlled study has been conducted, according to Dr. Bertoni, a neurologist at Creighton University, Omaha, Neb.
If the results are confirmed, Parkinson's disease patients should probably have a dermatologic evaluation, but there is no evidence to suggest how often that might be necessary, he said at his poster presentation during the meeting.
Of 2,106 patients with confirmed idiopathic Parkinson's disease who were screened prospectively for skin lesions by a dermatologist at 26 U.S. and 5 Canadian sites, 24 (1.1%) were newly diagnosed with melanoma, according to Dr. Bertoni. Another 3.4% of the patients had a history of prior melanoma.
In comparison with prevalence statistics available from the National Cancer Institute's Surveillance, Epidemiology, and End Results registry during 1997–2001, Parkinson's disease patients were 2.2 times as likely to have melanoma as were individuals in the general U.S. population.
Parkinson's disease patients had an age-adjusted relative risk for melanoma that was 10.6 times higher than that of individuals who participated in the voluntary, free skin cancer screening programs that were sponsored by the American Academy of Dermatology during 1985–1999, he said. After adjustment for gender alone, melanoma was 8.3 times more likely to occur in patients with Parkinson's disease than in AAD screening program participants.
In Dr. Bertoni's current study, melanoma was significantly associated with more severe Parkinson's disease, older age, and the presence of a greater number of risk factors for melanoma. Most patients (85%) were currently using or had used levodopa, but use of the drug, or any other dopaminergic agent, was not significantly associated with an increased incidence of melanoma.
There are no clear reasons for what might be driving an increased risk of melanoma in Parkinson's disease patients, Dr. Bertoni said.