Tamoxifen and malignant epithelial-nonepithelial tumours of the endometrium: report of six cases and review of the literature.

AIMS: To review the use of tamoxifen in malignant epithelial-nonepithelial tumours of the endometrium. Tamoxifen has been widely used for almost 20 years as adjuvant therapy for breast cancer. Large clinical trials have pointed out that long-term tamoxifen therapy increases the risk of uterine cancers. These tumours include endometrial carcinomas, stromal sarcomas, leiomyosarcomas as well as malignant mixed (epithelial-nonepithelial) tumours.

METHODS: We report here six more cases of malignant epithelial-nonepithelial tumours which, in addition to those reported in the literature, makes a total of 36 presented cases. The pathogenesis of such tumours remains unclear, but it has been claimed that unopposed oestrogenic stimulation due to the agonistic effect of tamoxifen might be involved, as in the case of endometrial carcinomas. Pelvic irradiation has also been incriminated, especiallly in women under 55 years of age.

RESULTS: Among 21 endometrial malignant epithelial-nonepithelial tumours associated with tamoxifen, seven occurred in women less than 55 years old. Five of them had previous pelvic irradiation. The data from the literature and from our series suggest that tamoxifen might favour the occurrence of malignant epithelial-nonepithelial tumours in women with breast cancer aged over 55 years, whereas in younger women both pelvic irradiation and tamoxifen might participate.