The additional risk of endometrial cancer associated with unopposed estrogen use in women with other risk factors

We analyzed data from a population-based case-control study of endometrial cancer. Our goal was to identify a subgroup of women in whom the additional cancer risk associated with unopposed estrogen use was sufficiently small so as to not be a deterrent to taking a hormone preparation of this type. R esearchers interviewed women with endometrial cancer (N = 553) and controls (N = 752) regarding hormone use. The additional risk of endometrial cancer associated with unopposed estrogen use did not vary substantially in the p resence or absence of hypertension, parity, oral contraceptive use, or smok ing. The results suggest that, although heavier women may experience a grea ter risk of endometrial cancer associated with unopposed estrogen use (8.2 per 1,000 per year) than lighter women (4.2 per 1,000 per year), long-term users in the latter group nonetheless face a substantial absolute increase in risk. We conclude that subdividing women on the basis of the presence or absence of other known risk factors for endometrial cancer fails to deline ate a subgroup that is exempt from the increased risk of this cancer associ ated with use of unopposed estrogens. 83.6% of estrogen users reported taki ng conjugated estrogens.