EVALUATING THE ENDOMETRIUM IN WOMEN ON TAMOXIFEN, A PILOT-STUDY TO COMPARE A GOLD STANDARD WITH AN OLD STANDARD

Our purpose was to compare the response of a progesterone challenge te st to endometrial histology in asymptomatic postmenopausal breast canc er patients on tamoxifen. Forty-eight asymptomatic (amenorrheic) postm enopausal breast cancer patients on 20 mg of tamoxifen daily for at le ast 6 months participated in the study. Patients underwent endometrial biopsy followed by ingestion of 10 mg daily of medroxyprogesterone ac etate (Provera) for 10 days. Biopsy samples were considered positive f or estrogen effect if they revealed proliferative endometrium, endomet rial hyperplasia, or endometrial cancer. The progesterone challenge te st was considered positive if the patient experienced vaginal bleeding within 10 days following completion of the Provera regimen. Three of the 48 women had positive progesterone challenge tests after endometri al biopsy. In each case, the corresponding histology was positive for estrogen effect. Positive estrogen effect was highly correlated with a positive progesterone challenge test [sensitivity 100%, 95% confidenc e interval (CI) = 0.44-1.00], while a negative estrogen effect was hig hly correlated with a negative progesterone challenge test (specificit y 100%, 95% CI = 0.92-1.00). The progesterone challenge test reliably predicted when the endometrium was unstimulated by tamoxifen and detec ted those women who histologically displayed endometrial stimulation. The progesterone challenge test could act as a readily available and c ost-effective tool for endometrial screening in asymptomatic postmenop ausal women on tamoxifen.