PIP: It is the committee's opinion that estrogens may become a promotional agent in the development of endometrial cancer in a small percentage of patients receiving estrogens. Since it appears that within the next few years 50% of all women by the age of 50 will have had a hysterectomy, and the disease occurs at an average age of 60 years, many women will have been removed from risk and few women's years of life may be lost. The risk is further reduced by the fact that early discovery of cancer of the endometrium has a cure rate of approximately 95%. Physicians administering estrogens should observe their patients carefully and perform curettage promptly for abnormal bleeding. More sophisticated methods of assessing the postmenopausal uterus are needed. Although the risk of estrogen users developing cancer of the breast has not been conclusively determined, patients with areas of thickening and nodularities in the breast should not receive estrogens. Women with sizable cysts should not receive any estrogenic hormone, and special consideration should be given in cases with close family histories of breast cancer. The most important factors are careful physical examination made by the patient and her physician at intervals of 6 months to 1 year and mammography when indicated.