Endometrial carcinoma and oral contraceptive agents.

Six patients who took oral contraceptive agents for 5 to 18 years developed endometrial neoplasia. Endometrial adenocarcinoma occurred in 4 of these patients and severe adenomatous hyperplasia occured in 2. Five of the 6 patients took sequential agents; 1 patient used a combined agent. An additional patient who took Premarin and Provera sequentially developed adenocarcinoma of the endometrium. Eighteen cases of endometrial adenocarcinoma and 7 cases of adenomatous hyperplasia in patients with long-term sequential oral contraceptive use have previously been reported by others. Progestogens may not be completely protective against the endometrial cancer-causing potential of the estrogens, especially in the sequential regimens.