PIP: The epidemiology of cancer of the endometrium is summarized. The findings are reported, and emphasis is on preventive approaches to cancer of the endometrium, particularly as to the role that physicians as well as women themselves can play. Attention is directed to incidence patterns, geographic distribution, age, race, time trends, survival rates, histopathologic consideration, and etiologic considerations (hormonal factors, obesity, diabetes mellitus, hypertension, and familial disposition). Recent reports indicate an increase in endometrial carcinoma, while the incidence of cervical carcinoma has substantially decreased. Endometrial cancer is usually a disease associated with postmenopausal women, mostly in the 6th and 7th decades, although rare cases have been reported in women under age 20 and over age 90. It is estimated that in 1981 there will be 38,000 newly diagnosed carcinomas of the endometrium and 3200 deaths due to endometrial carcinoma. There is little reliably comparable information available on endometrial cancer in different regions of the world. The incidence rate for endometrial cancer for U.S. white women is nearly double that for black women. For almost 4 decades before 1970 the incidence of cancer of the corpus uteri remained relatively stable. In a study conducted by Weiss et al. it was shown that the incidence of endometrial cancer increased by 34-75% between 1969 and 1973 in spite of a presumed increase in the rate of hysterectomy, which means a decreased population at risk during this same period. It is clear that obesity is a key risk factor for endometrial cancer, particularly as this obesity appears to be related to a high fat diet and consequently to higher levels of plasma urinary estrogens. It also appears that patients with heightened estrogenic stimulation reflected by a late menopause and heavy menstrual flow are at greater than average risk for endometrial cancer. As far as postmenopausal hormonal replacement therapy is concerned, the evidence appears strong that their use does increase the risk of endometrial cancer, particularly if such therapy is given for a long period of time and at relatively high doses. Possibly the ideal solution may be to give, when indicated, hormone replacement therapy at the least possible estrogen dose and together with progesterone, and to take the medication in cycles rather than on a constant basis.