Oral Contraceptives Use and Liver Cancer Risk: A Dose–Response Meta-Analysis of Observational Studies

Studies about the association between oral contraceptives use and liver cancer risk have generated controversial results. Therefore, a meta-analysis of cohort and case–control studies was performed to quantitatively summarize the existing evidence. Eligible studies were identified by a computer search of PubMed and Embase databases and handed-search of reference lists, without any limitations. Study-specific risk estimates (RRs) with 95% confidence intervals (CIs) were combined with random-effects model. A total of 17 articles were included in this meta-analysis. Overall, there was no statistically significant association between oral contraceptives use and liver cancer risk (RR: 1.23, 95% CI: 0.93–1.63). In a dose-analysis of meta-analysis, a linear relationship between oral contraceptives use and liver cancer risk (P for linearity = 0.391) was found, although this correlation was not statistically significant. Oral contraceptives use was not positively associated with the risk of liver cancer.