Abstract
Biochemical properties, such as the activities of eight carbohydrate-metabolism-linked enzymes and four acid hydrolases, and histological characteristics of growing and regressing DMBA-induced mammary tumors of the SD-rat after ovariectomy or treatment of the host with hexesterol, tamoxifen, and 3,4-bis(3'-hydroxyphenyl)hexane were determined. Significant differences were found between growing and regressing tumors regardless of the treatment animals had been subjected to. Only few differences in biochemical parameters could be found within the group of tumors regressing due to the applied therapy. The histological signs of regressing tumors were very diverse, but no phenomenon typical of a specific treatment could be found. It cannot be decided whether the partial antiestrogen, 3,4-bis(3'-hydroxyphenyl)hexane unfolds its antimammary tumor activity by means of its estrogenic or its antiestrogenic potency. The hypothesis that estrogens inhibit mammary tumor growth by directing neoplastic cell metabolism toward secretion is not supported by these findings.