People with Parkinson's disease may have double the risk for melanoma

Parkinson's disease is a brain disorder that causes tremors and difficulty with movement and walking. It affects about one million people in the United States.

"Past studies linking Parkinson's disease and melanoma have not been conclusive, so we wanted to explore a larger group of studies to see whether the link was consistent," said study author Honglei Chen, MD, PhD, with the National Institute of Environmental Health Sciences, a division of the National Institutes of Health in Research Triangle Park, N.C., and a member of the American Academy of Neurology.

The research examined 12 studies conducted from 1965 and 2010 that looked at the possible association between Parkinson's disease and melanoma. Most of the studies had fewer than 10 cases with both conditions.

The study found that men with Parkinson's disease were twice as likely as those without Parkinson's to have melanoma. Women with Parkinson's disease were one-and-a-half times as likely to be diagnosed with the dangerous form of skin cancer compared to women without Parkinson's. There was no clear link found between Parkinson's and non-melanoma skin cancer.

"Parkinson's disease patients in general have a lower risk for cancer, smoking-related cancers in particular, but they may have a higher risk for melanoma. One possible explanation for the link between Parkinson's and melanoma is that the two diseases may share some genetic or environmental risk factors," Chen said. "However, our understanding of this link is very preliminary."

The study was supported by the National Institute of Environmental Health Sciences.