[Tamoxifen-induced progesterone receptors in breast tumors]

Estrogen and progesterone receptors were assayed in 86 patients with breast cancer following 7-day treatment with 20 mg tamoxifen. The results were compared with the data on the receptor status of 127 untreated patients with breast cancer. Mean progesterone receptor level was significantly increased whereas that of estrogen receptors was significantly decreased in patients aged 20-49 and 60-69 years. It is suggested that tumors in which stimulated progesterone receptor level is higher than 50 fmol/mg protein be considered hormone-dependent.