These women invariably have specific risk factors such as morbid obesity, chronic anovulation, and hereditary syndromes. Endometrial cancer is more common in white women when compared to black women. Uterine sarcomas, regardless of the histologic subtype, are more common in black women. Leiomyosarcomas tend to occur more often between the ages of 30-50, as compared to carcinosarcomas and endometrial stromal sarcomas, which have much higher incidence after age 50. Women with a history of pelvic radiation are at greater risk for carcinosarcomas, and to a lesser extent leiomyosarcomas.
Nulliparous women are at greater risk for both types of sarcomas.
There are protective effects noted with combination oral contraceptives. Past or current use of oral contraceptives prevents about 2,000 cases of endometrial cancer each year. For these patients, relative risk for developing endometrial cancer is approximately .5. Although smoking decreases the risk of endometrial cancer, its increased risk of lung cancer and other major morbidities far outweighs this benefit. While unopposed estrogens have an adverse effect in terms of risk, it is well known that progestins have a protective effect of the endometrium even when administered in combination with estrogen replacement.