BREAST-CANCER RISK AND ALCOHOL-CONSUMPTION - RESULTS FROM A LARGE CASE-CONTROL STUDY

Background. Alcohol use is associated with breast cancer in many epide miological studies. Most, however, have measured risk from recent cons umption patterns, and only a few include analyses for duration of drin king or age that a woman started to drink. The authors studied the eff ect of these variables, as well as of recent alcohol consumption patte rns, on breast cancer risk. Methods. Data from a large case-control st udy conducted in Long Island, New York from 1 January 1984 to 31 Decem ber 1986 were used. A total of 1214 women aged 20-79 years with incide nt breast cancer were interviewed. A control was selected for each cas e from driver's license files, and matched on age and county of reside nce. Alcohol consumption was measured as: ever versus never, grams of alcohol per day, age started drinking, and total years drinking. Resul ts. After adjustment for breast cancer risk factors, the odds ratio fo r ever versus never drinking was 1.40 (95% confidence interval [CI] 1. 09-1.79); odds ratios for >0-5 and greater than or equal to 5 grams of alcohol use per day, as compared to nondrinkers, were 1.29 (95% CI : 1.00-1.65) and 1.46 (95% CI : 1.13-1.89), respectively, Age when drink ing began was not related to breast cancer risk, but the greater the t otal years of drinking, up to 40 years (odds ratio 1.48, 95% CI : 1.13 -1.93), the greater the risk. However, when grams per day and duration of drinking were simultaneously included in the multivariate model, d uration was not important as a risk factor. This suggests that intensi ty of drinking may be the important factor for breast cancer risk. Aft er covariate adjustment, risk from alcohol intake did not differ betwe en pre-and postmenopausal women. Conclusions. These data support the b elief that alcohol is associated with breast cancer risk.