Tamoxifen-induced increase in cytosol progestin receptor levels in a case of metastatic endometrial cancer.

A patient with endometrial carcinoma metastatic to the groin has had serial cytosol estrogen (ERc) and progestin (PRc) receptor determinations during hormonal therapy. The primary lesion was well differentiated and a left iliac node metastasis had high ERc and borderline PRc levels. PRc levels increased substantially in a subsequently appearing right groin metastasis at three times during the clinical course when the patient was treated with the antiestrogen tamoxifen. The patient had a partial response to the first course of tamoxifen and at one later time briefly had stabilized disease on tamoxifen plus medroxyprogesterone acetate. Tamoxifen with and without progestin should be further evaluated in the treatment of endometrial carcinoma.