Article révisé par les pairs
Résumé : The MXT mouse mammary carcinoma is a new transplantable tumour which contains significant amounts of oestrogen receptors and shows a hormone-sensitive growth. We analyzed the response of the tumour to pharmacological doses of tamoxifen and oestrogens. Tamoxifen administration at doses ranging from 0.5 to 50 mg/kg produced a marked reduction of tumour growth. Furthermore, the drug considerably prolonged the survival of the animals. Uterus and vagina from treated mice displayed a histological pattern indicative of a strong oestrogenic stimulation. These endocrinological observations suggest that the antitumour effect of tamoxifen might be associated with its oestrogenic activity. In keeping with this view, we found that oestradiol and diethylstilboestrol (5 and 50 mg/kg) were more effective than tamoxifen. The data reported definitively demonstrate the efficacy of tamoxifen on hormone-sensitive mouse mammary tumours and that the antitumour potency of the drug is derived from its oestrogenic property.