To summarize the review, the medical literature indicates that certain constitutional factors as well as the use of exogenous estrogen are associated with an increased risk of endometrial cancer. In addition, the absolute increase in the risk of this neoplasm with use of estrogen does not appear to be constant but depends upon the specific constitutional factors present. Therefore, particular caution should be exercised in prescribing replacement estrogens for women who already have an increased risk of endometrial cancer, such as those who are overweight or those who give a history of late onset of menopause. It should be noted, however, that the greatest absolute increase in risk with estrogen use appears to occur in women with no other known risk factors for the disease.