Sex hormone binding globulin and risk of breast cancer in postmenopausal women: a meta-analysis of prospective studies.

Previous studies on the association between sex hormone binding globulin (SHBG) level and risk of breast cancer in postmenopausal women reported conflicting results. A meta-analysis of prospective studies was performed to evaluate the association between SHBG level and risk of breast cancer in postmenopausal women. Pubmed (1980 to July 2014) and EMBASE (1988 to July 2014) were searched for eligible studies. Eligible studies were prospective cohort or nested case-control studies on the association between SHBG level and risk of breast cancer in postmenopausal women. Meta-analysis using random-effects model was performed to calculate the pooled risk ratios (RRs) with 95% confidence intervals (95% CIs). Of 946 studies identified, 26 prospective studies from 21 publications were finally included in the meta-analysis. In postmenopausal women, the pooled RR for breast cancer comparing highest with lowest categories of SHBG was 0.64 (95% CI 0.57-0.72, p<0.001, I(2)=6.5%). The pooled RRs were not obviously altered in the sensitivity analyses and subgroup analyses. In cumulative meta-analysis, a more significant association between SHBG level and risk of breast cancer in postmenopausal women was observed as evidence accumulated by publication year. There was no obvious risk of publication bias. High SHBG level is significantly associated with decreased risk of breast cancer in postmenopausal women, and it's a protective factor of breast cancer in postmenopausal women. © Georg Thieme Verlag KG Stuttgart · New York.