Steroid Hormone Levels in Patients with Advanced Breast Cancer during Therapy with Droloxifene: A Pilot Study

Antiestrogens, particularly tamoxifen, are effective in the treatment of pre- and postmenopausal women suffering from all stages of breast cancer. Unfortunately, many patients become resistant to tamoxifen during therapy, which allows the tumor to progress. Thus, a preclinical recognition of tumor progression, i.e. by monitoring serum hormone levels, could be worthwhile. The serum levels of dehydroepiandrosterone sulfate and estradiol of postmenopausal women with advanced breast cancer treated by the new antiestrogen droloxifene were therefore checked. However, only non-significant changes in the hormone levels during droloxifene therapy were observed, and no relation was found between hormone levels and the course of the disease, success or exhaustion of droloxifene application, or development of tumor progression. Our data do not confirm earlier findings reported in the literature that measurement of hormones seems to be suitable for an early indication of tumor progression during an antiestrogen therapy before its clinical manifestation.