Relationship between sex hormone binding globulin and estrogen receptors in breast cancer.

It has been suggested that the level of sex hormone binding globulin (SHBG) is a better predictor of response of breast cancer to hormone treatment than the measurement of estrogen receptor (ER). However, no correlation of SHBG with ER status has been shown. To define the relationship between SHBG and the ER, the following study was undertaken. Fifty women with breast cancer and known ER status had SHBG measured by dextran-coated charcoal saturation analysis. The mean SHBG in all ER-positive patients was 20.7 +/- 2.4 (ng DHT bound/mL) and in all ER-negative patients was 11.5 +/- 2.0 (p less than 0.01). The mean premenopausal level of SHBG was 22.2 +/- 3.8 ng/mL and postmenopausal level was 20.0 +/- 5.7 ng/mL. There was no significant difference between these groups. ER-positive patients on tamoxifen had a SHBG of 29.8 +/- 9 ng/mL and ER-negative subjects on tamoxifen had a mean SHBG level of 8.3 +/- 3.4 ng/mL, p less than 0.01. ER-positive patients have a higher SHBG level than ER-negative patients; furthermore, this difference between ER-positive and ER-negative subjects was further demarcated by changes in SHBG after the subjects had been placed on tamoxifen.