SHBG and breast cancer: The effect of both testosterone and SHBG on ER-stratified breast cancer has been previously studied [29], in which both total (OR = 1.19, 95% CI:1.12, 1.26) and bioavailable testosterone (OR = 1.23, 95% CI:1.12, 1.34) were associated with increased risk of ER-positive breast cancers.