Postmenopausal Hormone Therapy is Associated with in Situ Breast Cancer Risk

Background: The relationship between postmenopausal hormone therapy (HT) and invasive breast cancerhas been extensively investigated, but that with breast carcinoma in situ (BCIS) has received relatively littleattention. The aim of our present study was to review and summarize the evidence provided by longitudinalstudies on the association between postmenopausal HT use and BCIS risk.
Methods: A comprehensive literaturesearch for articles published up to May 2012 was performed. Prior to performing a meta-analysis, the studies wereevaluated for publication bias and heterogeneity. Relative risk (RR) or odds ratio (OR) values were calculatedusing 14 reports (8 case–control studies and 6 cohort studies), published between 1986 and 2012.
Results: Therewas evidence of an association between ever postmenopausal estrogen use and BCIS based on a random-effectsmodel (RR = 1.25, 95% confidence interval (CI) = 1.01, 1.55). However, we found no strong evidence of anassociation between ever postmenopausal estrogen combined with progesterone use and BCIS using a randomeffectsmodel (RR = 1.55, 95% CI = 0.95, 2.51). Furthermore, our analysis showed a strong association between“> 5 years duration” of estrogen or estrogen combined with progesterone use and BCIS. Furthermore, currentuse of any HT is associated with increased risk of BCIS in cohort studies. Additional well-designed large studiesare now required to validate this association in different populations.