Hormone Therapy and Risk of Lung Cancer: A Meta-Analysis

Background: The association between hormone therapy (HT) use and lung cancer risk is inconsistent in epidemiological studies. This meta-analysis was conducted to examine the association between HT and lung cancer risk. Methods: We searched MEDLINE (PubMed), EMBASE, and the Cochrane Library in April 2008. All articles searched were independently reviewed and selected by two evaluators according to predetermined inclusion and exclusion criteria. Results: We included a total of 11 studies (8 case-control studies and 3 prospective cohort studies), involving a total of 220,599 participants. When all studies were pooled, the odds ratio (OR) of HT use for lung cancer risk was 0.87 (95% confidence interval (CI) 0.74-1.02). In subgroup meta-analyses, there was no association among cohort studies (relative risk (RR) 1.01; 95% CI 0.74-1.38), while there was a significant association between HT use and lung cancer risk among case-control studies (OR 0.81; 95% CI 0.68-0.97) based on a random-effects model. No significant association between HT use and lung cancer risk was observed in most of the subgroup meta-analyses by methodological quality of study, type of HT use, duration of HT use, and histology of lung cancer, while significant protective effects were observed among former and never smokers except for current smokers. However, cumulative meta-analyses based on year of publication showed a distinct trend toward a protective effect of HT use on lung cancer risk in the recent studies. Conclusions: Overall, the findings of this meta-analysis do not support the hypothesis that there is a link between HT use and lung cancer risk. Our findings should be evaluated in further prospective cohort studies.