Exploring the risk of melanoma in people with Parkinson's disease: a systematic review and meta-analysis.

INTRODUCTION The potential association between Parkinson's disease (PD) and melanoma has received increasing attention in the literature, yet its strength and direction remain incompletely understood. Previous studies vary considerably in diagnostic ascertainment, temporal relationship between the two conditions and analytic approach. This systematic review and meta-analysis aimed to evaluate this association while accounting for these methodological differences.

Methods

A comprehensive search of four databases from inception to May 25, 2025 was conducted. Methodological study quality was evaluated using Newcastle-Ottawa Scale and JBI Analytical Cross-sectional checklist. GRADE was applied to assess the overall certainty of evidence. A random-effects model with restricted maximum likelihood estimation and Hartung-Knapp adjustment was performed to calculate pooled odds ratios with 95% confidence intervals. Heterogeneity was assessed using I2.

Results

Eighteen studies met the inclusion criteria for this review, of which three were eligible for the meta-analysis. The pooled odds ratio was 2.55 (95% CI: 0.09-73.07). Although the point estimate was above the null, the confidence interval was extremely wide and included an OR of 1.0. Between-study heterogeneity was observed (I2 = 82.2%), and the certainty of evidence was rated as very low.

Conclusion

The available evidence regarding the association between PD and melanoma remains very uncertain. Although the pooled OR was above the null, the wide confidence interval, substantial heterogeneity and very low certainty of evidence prevent the drawing of firm conclusions regarding the magnitude or direction of this association. Current evidence is insufficient to support PD-specific melanoma screening recommendations, and further methodologically robust studies are warranted.