VANCOUVER, B.C. — Malignant melanoma is associated with Parkinson's disease, Dr. Darrell S. Rigel reported at the Sixth World Congress on Melanoma.
A case control study of 862 melanoma patients culled from 10 academic centers found that 3% also had Parkinson's disease, compared with only 1% of 862 age- and sex-matched controls, Dr. Rigel, of New York University, New York, said in a poster presentation.
Of the 351 subjects over the age of 60 years, 7% had Parkinson's disease, compared with 3% of the controls.
The study is the first to report an increased prevalence of any nonneoplastic disease in malignant melanoma patients, and it is consistent with reports that have suggested an increased incidence of melanoma in Parkinson's disease patients, Dr. Rigel said.
Parkinson's disease patients have been reported to have a lower rate of cancer overall, except for thyroid cancer and melanoma.
Possible reasons for the association include the fact that melanocytes and dopaminergic neurons are derived from the same embryonic tissue, that a particular cytochrome P450 polymorphism is associated with both diseases, and that neuromelanin and cutaneous melanin are similar.
It also has been suggested by some that levodopa plays a role, since there are shared pathways between the synthesis of dopamine and melanin, and the Physicians' Desk Reference lists levodopa as a contraindication in patients with suspicious skin lesions or a history of melanoma.
However, case control studies have suggested that the drug is not responsible for the association between melanoma and Parkinson's disease.