Parkinson Disease and Melanoma: Confirming and Reexamining an Association

Objective: To examine an association between melanoma and Parkinson disease (PD). Patients and Methods: Phase I: Rochester Epidemiology Project records were used to identify (between January 1, 1976, and December 31, 2013) patients with PD in Olmsted County, Minnesota, with 3 matched controls per case. After review, JMP statistical software with logistic regression analysis was used to assess the risk of preexisting melanoma in patients with PD vs controls. Phase II: All Rochester Epidemiology Project cases of melanoma were identified (between January 1, 1976, and December 31, 2014), with 1 control per case. A Cox proportional hazards model was used to assess the risk of developing PD after the index date in cases vs controls, and Kaplan-Meier analysis was performed to determine the 35-year cumulative risk of PD. A Cox proportional hazards model was used to assess the risk of death from metastatic melanoma in patients with melanoma without PD compared with those with PD. Results: Phase I: Patients with PD had a 3.8-fold increased likelihood of having preexisting melanoma as compared with controls (95% CI, 2.1-6.8; P<.001). Phase II: Patients with melanoma had a 4.2-fold increased risk of developing PD (95% CI, 2.0-8.8; P<.001). Kaplan-Meier analysis revealed an increased 35-year cumulative risk of PD in patients with melanoma (11.8%) compared with controls (2.6%) (P<.001). Patients with melanoma without PD had a 10.5-fold increased relative risk of death from metastatic melanoma compared with patients with melanoma with PD (95% CI, 1.5-72.2) (P=.02). Conclusion: There appears to be an association between melanoma and PD. Further study is warranted; but on the basis of these results, physicians may consider counseling patients with melanoma about PD risk and implementing cutaneous and ocular melanoma surveillance in patients with PD. (C) 2017 Mayo Foundation for Medical Education and Research