People with Parkinson's disease face an increased risk of the most deadly type of skin cancer, new research confirms.
Exams of more than 2,000 people with Parkinson's disease found that about 1 percent currently had melanoma, Dr. John M. Bertoni of the University of Nebraska Medical Center in Omaha and his colleagues found. Based on the findings, they say, people with the degenerative nerve disease should receive regular skin cancer screening.
A number of studies have found a higher risk for melanoma among people with Parkinson's disease, which occurs when brain cells that produce dopamine — a signaling chemical with many important functions in the brain — die off. But it hasn't been clear whether this increased risk is due to the drugs people take to treat Parkinson's disease or to the disease itself.
To investigate further, Bertoni and colleagues at 31 different centers across North America studied 2,106 patients with Parkinson's disease. The patients first underwent a neurological exam, and then at a second visit had a dermatologic exam, which included biopsies of any suspicious moles or growths.
The researchers found 20 localized melanomas among the study participants and four that had spread beyond the original site, while another 68 patients reported having a history of melanoma.
Among the patients living in the U.S., the likelihood of having melanoma was more than double that of the general U.S. population, the researchers found. When the findings were compared to statistics from skin cancer screening programs run by the American Academy of Dermatology, the researchers found a more than seven-fold increased risk of melanoma for U.S. Parkinson's patients.
Since the 1970s, a number of case reports have suggested that levodopa therapy for Parkinson's disease increases the risk of skin cancer. In the current study, nearly 85 percent of the patients had taken levodopa, but the researchers found no evidence that this drug was associated with melanoma risk.
This study, conclude Bertoni and colleagues, provides more evidence that melanoma occurs more often in patients with Parkinson's disease than in the population at large and "supports increased melanoma screening" in patients with Parkinson's disease.
According to the Mayo Clinic, a change in an existing mole or the development of an unusual growth on the skin could indicate melanoma. Watch for the following indications — the A-B-C-D-E guide developed by the American Academy of Dermatology:
• A is for asymmetrical shape.
• B is for irregular border.
• C is for changes in color — growths that have many colors or an uneven distribution of color.
• D is for diameter (moles larger than 1/4 inch).
• E is for evolving — moles than grow or changes color or shape.
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