Systematic review of case-control studies: oral contraceptives show no effect on melanoma risk.

A systematic review of the research literature was conducted to elucidate the role of oral contraceptives (OCs) in the development of malignant melanoma. The retrieval systems MEDLINE and CANCERLIT identified 18 case-control studies of this relationship and study-specific odds ratios (ORs) were recalculated in the meta-analysis. These ORs ranged from 0.13 to 1.85; however the majority of studies yielded ORs within the 0.82-1.15 range. The summary ORs estimated from both fixed effects and random effects models were each 0.95; the 95% confidence intervals were 0.87-1.04 and 0.87-1.05 respectively indicating no association. Separate analyses of the OC-malignant melanoma association by year of study publication type of case group source of the control group and type of exposure ascertainment corroborated this lack of significant effect.