[Antiestrogens: a new endocrine treatment possibility in metastasizing breast neoplasms. Experiences of the Swiss Cooperative Cancer Study Group with tamoxifen].

The detection of specific hormone receptors in normal and tumor tissue has brought new insight into the mechanisms of action of hormones and anti-hormones. The Swiss Cooperative Cancer Study Group (SAKK) has evaluated the antitumor effect of the new antiestrogenic substance tamoxifen in metastatic breast cancer. 158 postmenopausal patients treated with 20 mg/d tamoxifen by mouth are evaluable at present time. Complete and good partial remissions were achieved in 39 patients (25%) largely with soft tissue but also lung and bone metastases. Tamoxifen was well tolerated and caused few serious complications such as thrombosis/pulmonary embolism and hypercalcemia. These results confirm already published experience with tamoxifen, which may replace the estrogens as the primary endocrine treatment in postmenopausal mammary carcinoma metastasizing to soft tissues, lung and bone.