Progestin therapy of endometrial, breast and ovarian carcinoma. A review of clinical observations.

A survey of the literature shows that in studies employing standardized criteria to define the response to progestin therapy, an objective remission is achieved in about one-third of patients with endometrial and breast cancer, and it is much less frequent in ovarian malignancy. The response is seldom complete and it is mostly of a short duration. There is a tendency towards an increased response-rate with increased dosage of progestin, in both endometrial and breast carcinoma, while the route of administration appears to be of minor importance. The clinical benefit of adjuvant progestin therapy in endometrial cancer is unproven. Simultaneous therapy with progestin and cytotoxic drugs seems not to increase the survival figures obtainable by cytotoxic therapy alone. The antiestrogen tamoxifen has an established efficacy in all these malignancies. The spectra of tumors sensitive to tamoxifen and to progestin are not completely identical. The optimal combination of these drugs awaits results from prospective studies. Selection of patients for progestin therapy with a sufficient degree of accuracy is not feasible by use of clinical or histological parameters. On the other hand, estrogen receptor determination already has an established position in the clinical evaluation of the sensitivity of breast cancer to endocrine therapy. The assay of progestin receptors from endometrial carcinoma tissue also seems to give reliable information; correct prediction was observed in 86% when the receptor data from five studies with 105 progestin therapies were correlated with the treatment results.