Alcohol consumption and the risk of breast cancer: a report from the Tecumseh Community Health Study.

The relationship between prior alcohol consumption and the risk of breast cancer was studied in 1954 women in the Tecumseh Community Health Study (TCHS) who entered the cohort in 1959-1960 and were followed potentially for 28 years. The mean alcohol consumption at baseline was 0.89 (SD 2.2) oz/week for premenopausal women and 0.85 (SD 2.2) oz/week for postmenopausal women. Only 25% of the cohort consumed more than 0.5 oz of ethanol/week or about 1.6 g/day. The adjusted relative risks (RRs) for breast cancer associated with the use of ethanol vs never drinking were 0.93 (95% CI, 0.40-2.18) for ex-drinkers, 1.08 (95% CI, 0.64-1.82) for 0- less than 1 drink/day, 1.23 (95% CI, 0.49-3.10) for 1- less than 2 drinks/day and 1.12 (95% CI, 0.25-5.01) for greater than or equal to 2 drinks/day. There were only 37 subjects in the group at the highest level of consumption (greater than or equal to 2 drinks/day). There was no significant interaction between alcohol and the period of onset of breast cancer (premenopausal or postmenopausal). In the TCHS, alcohol consumption generally at levels not exceeding 2 drinks/day, was not significantly associated with an increased risk of breast cancer. Although we have found little excess risk associated with alcohol consumption, the wide confidence intervals summarized above are not inconsistent with previously published reports that have suggested a modest positive association.