Hormonal treatment of endometrial carcinoma: an overview and new development in biology.

Progestins are routinely used in the treatment of endometrial carcinomas with about 30% response rate. After a 10-12 month mean response time, the tumors begin to regrow. This clinical situation has been reproduced in the experimental model for human endometrial carcinomas, developed by us. The model consists of growth and maintenance of human endometrial carcinomas of different histologic grade and sex steroid steroid receptor content, in defined hormonal milieu, by serial transplantation in athymic nude mice. Biologically and clinically relevant information on the role of steroid receptors in eliciting hormonal responses, the effect of combination treatment with tamoxifen and progestin and the mechanism of resistance to this treatment after an initial response have been obtained. These studies form the basis for designing and testing rational treatment strategies for human endometrial carcinomas.