Meta-analysis of the relationship between Parkinson disease and melanoma

Abstract

Objective: To assess the epidemiologic evidence on melanoma in relation to Parkinson disease (PD) via systematic review and meta-analysis.

Methods: Epidemiologic studies on melanoma and PD were searched using PubMed, Web of Science, Scoups, and Embase (1965 through June 2010). Eligible studies were those that reported risk estimates of melanoma among patients with PD or vice versa. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using random-effects models.

Results: We identified 12 eligible publications on melanoma and PD: 8 had fewer than 10 cases with both PD and melanoma, and 7 provided gender-specific results. The pooled OR was 2.11 (95% CI 1.26-3.54) overall, 2.04 (1.55-2.69) for men, and 1.52 (0.85-2.75) for women. Analyses by temporal relationship found that melanoma occurrence was significantly higher after the diagnosis of PD (OR 3.61, 95% CI 1.49-8.77), but not before PD diagnosis (OR 1.07, 95% CI 0.62-1.84). Further analyses revealed that the lack of significance in the latter analysis was due to one study, which when excluded resulted in a significant association (OR 1.44, 95% CI 1.06-1.96). We also analyzed nonmelanoma skin cancers in relation to PD and found no significant relationship (OR 1.11, 95% CI 0.94-1.30).

Conclusions: Collective epidemiologic evidence supports an association of PD with melanoma. Further research is needed to examine the nature and mechanisms of this relationship.

Figure 1.. Association between melanoma and Parkinson disease (PD) according to temporal relationship

Subtotal = pooled odds ratios (ORs) within each subcategory. Overall = pooled OR for all studies. Squares indicate study-specific ORs; error bars indicate 95% confidence intervals (CIs); diamonds indicate ORs and 95% CIs from pooled analyses. One study that evaluated the occurrence of melanoma after PD diagnosis was excluded because no cases were observed.

Figure 2.. Association between melanoma and Parkinson disease (PD) by gender

Subtotal = pooled odds ratios (ORs) within each gender group. Overall = pooled OR for all studies where gender-specific data were available. Squares indicate study-specific ORs; error bars indicate 95% confidence intervals (CIs); diamonds indicate ORs and 95% CIs from pooled analyses. In men, reference 9 provided data separately for melanoma before and after PD diagnosis.

Figure 3.. Association between nonmelanoma skin cancers and Parkinson disease (PD)

Overall = pooled odds ratio (OR) for all studies that reported a risk estimate. Squares indicate study-specific ORs; error bars indicate 95% confidence intervals (CIs); diamonds indicate ORs and 95% CIs from pooled analyses. Reference 13 provided data separately for nonmelanoma skin cancers before and after PD diagnosis. Reference 19 provided data separately for men and women.

Figure 4.. Funnel plot of studies on melanoma and Parkinson disease

The log odds ratio (OR) from each study is plotted on the horizontal axis, and standard error (SE) on the vertical axis.