There is a link between Parkinson’s disease and melanoma, with possible etiologies including family history and common genetic susceptibility, according to recently published study results.
“Given that [levodopa] is a substrate in melanin synthesis, there existed a concern that this therapy [for Parkinson’s disease] might cause melanoma,” researchers from the University of Minnesota Medical School, Minneapolis, wrote.
The researchers conducted a literature search of PubMed and Google Scholar to identify possible etiological links explaining the connection between Parkinson’s disease (PD) and melanoma. Search terms included “Parkinson’s disease, Parkinson’s, melanoma, melanoma + Parkinson’s disease, alpha-synuclein and melanoma” and other combinations of those words.
There was an overall 27% decreased risk for cancer diagnoses in patients with PD (relative risk = 0.73; 95% CI, 0.63-0.83). There were “uncharacteristically high” rates of co-occurrence of PD and breast cancer (1.24 standard incidence ratio) and of PD and melanoma (1.95 standard incidence ratio).
A family history of melanoma was related to a higher risk for PD: a first-degree relative with melanoma was associated with higher risk of PD for women (RR = 1.75; 95% CI, 1.1-3.9) and for men (RR = 2.1; 95% CI, 1-3.1).
Lighter hair and skin color also were related to a higher risk for PD. A Nurses’ Health Study of 130,000 study participants from 1980 to 2002 showed a relative risk of 1 for black hair (reference); 1.4 for brown hair; 1.61 for blonde hair; and 1.93 for red hair.
Pigmentation genes in neural-derived cells, pesticides, MC1R polymorphisms and abnormal cellular autophagy were other possible connections identified in the studies.
“Both PD and melanoma are likely multifactorial diseases including genetic and environmental risk factors, and further research will be needed to completely evaluate this link,” the researchers concluded. “It is prudent that dermatologists be aware of this increased risk of melanoma and explain this risk to their patients with PD and recommend them sun protection, self-surveillance and periodic skin check-up.” – by Bruce Thiel
Disclosure: The researchers report no relevant financial disclosures.