[Mechanism and classification of hormone therapy for human breast cancer studied by changes of SHBG binding capacity]

We determined SHBG titer before and during hormone therapy for breast cancer. The increased SHBG titer was 78 +/- 29 pmol/ml of plasma in DES responsive breast cancer. However that of DES non-responsive breast cancer was 31 +/- 22 pmol/ml of plasma (p less than 0.01). SHBG titer was increased during the administration of tamoxifen and was decreased during that of fluoxymesterone and after surgical hormone therapy. These results indicate that the mechanism of hormone therapy was due to a decreased free estradiol, which was caused by increased SHBG titer and resection of the ovarium or adrenal gland.