Menopausal hormone therapy and risk of lung cancer-Systematic review and meta-analysis.

OBJECTIVES Lung cancer rates increase among women in many regions of the world. To explore whether menopausal hormone therapy (MHT) plays a role. METHODS We conducted a systematic search of the literature and performed meta-analyses of cohort studies (C), case-control studies (CC), randomized controlled trials (RCTs), and cancer registry studies (CR) to analyse the impact of estrogen therapy (ET), estrogen/progestin therapy (EPT) and any hormone therapy (HT) on lung cancer risks. We explored associations between ever-use of therapies and risks, analysed annual changes of risk, and the impact of therapies on histological subtypes. We calculated summary odds ratios, relative risks, 95% confidence intervals (CI; fixed-effects model), and assessed heterogeneity across studies. Eighteen studies were eligible (9 CC, 4 C, 3 RCT, 2 CR). RESULTS We found a significant increase of risk - 76.2% - in non-smoking women with adenocarcinoma (CI 1.072-2.898) reporting ever-use of HT. Estrogen plus progestin therapy does not change the risk; however, the pooled analysis of 2 RCTs points at an increased risk (RR 1.359; CI 1.031-1.791). Our further results should be interpreted with caution as significances were found in analyses only when smoking and non-smoking women, various hormone regimens, or histological subtypes, respectively, were pooled. CONCLUSIONS Dedicated studies designed to more adequately delineate the role of MHT are necessary to substantiate whether use of MHT is a risk factor for this or other types of lung cancer.