Alcohol consumption and postmenopausal endometrial cancer: results from the Iowa Women's Health Study.

At least three case-control studies have examined the association between alcohol consumption and endometrial cancer; two studies showed inverse associations, and a third a positive association. To our knowledge, no prospective studies of this association have been reported. The association between alcohol and endometrial cancer was examined in the Iowa Women's Health Study (United States), a prospective study of postmenopausal women. Information on alcohol consumption and other variables was obtained through a mailed questionnaire in January 1986. Through December 1990, 167 incident endometrial cancer cases occurred in the at-risk cohort of 25,170 women. Multivariate-adjusted relative risks (RR) and 95 percent confidence intervals (CI) were computed using Cox proportional hazards regression controlling for age, body mass index (BMI), parity, age at menopause, and noncontraceptive estrogen use, and to determine multiplicative interactions. The RRs of endometrial cancer associated with < 4.0 and > or = 4.0 g of alcohol per day compared with abstainers were 0.7 (CI = 0.5-1.1) and 1.0 (CI = 0.7-1.6), respectively. No statistically significant association between endometrial cancer and consumption of either beer, wine, or liquor was observed. There was no interaction between alcohol and any other endometrial cancer risk factors, including BMI or noncontraceptive estrogen use. These data do not support an association between alcohol and endometrial cancer among postmenopausal women.