The associations between alcohol and colon and rectal cancers were examined in the Iowa Women's Health Study.

In January 1986, 41837 postmenopausal women, aged 55-69, completed a questionnaire including usual alcohol intake and other information.

Through December 1990, 237 incident colon and 75 rectal cancer cases occurred.

Mantel-Haenszel age-adjusted relative risks (RR) and 95% confidence intervals (Cl) for consumers of <4.0 and >=4.0 g of alcohol per day compared to abstainers were 1.07 (0.61-1.89) and 1.27 (0.72-2.24) (P for trend=0.46) for rectal cancer.

Alcohol intake was inversely associated with distal colon cancer (RR for <4.0 and >=4.0 g of alcohol per day were 0.64 and 0.69 respectively, P for trend=0.04), which was specific to wine; however, no association was observed with proximal colon cancer (P for trend=0.94).