Hormone replacement therapy and lung cancer risk in women: a meta-analysis of cohort studies: Hormone replacement therapy and lung cancer risk.

Background: Discordant results about the causal relationship between hormone replacement therapy use (HRT) and lung cancer risk in women had been reported. We therefore conducted a meta-analysis of cohort studies to evaluate this association. Methods: The PubMed and Embase databases were searched. Fixed- or random-effects model was used to pool the study-specific relative risks (RRs) with corresponding 95% confidence intervals (CIs). Sensitivity analysis, publication bias, and subgroup analysis were performed. Results: A total of 13 cohort studies met the inclusion criteria. Combined results indicated that compared with nonusers, women with HRT use were at a decreased risk (RR: 0.95, 95% CI: 0.91-0.99, I-2=30.8%, P for heterogeneity=.137). In subgroup analysis by geographic area, smoking statue, type of hormones, and histology type of lung cancer, no significant association between HRT use and lung cancer was observed in most subgroups except in those studies which reported risk estimates adjusted for age, body mass index, smoking, and other confounders (RR: 0.95, 95 CI: 0.91-0.99, I-2=33.0%, P for heterogeneity=.214). Both Begg funnel plot and Egger test (P=.243) suggested no evidence for publication bias. Conclusion: Our meta-analysis suggests ever use of HRT is associated with a decreased risk of lung cancer in women.