Having More than Two Alcoholic Drinks at a Time Increases Younger Women's Breast Cancer Risk by 80 Percent

BUFFALO, N.Y. -- Results from a case-control study on alcohol consumption and breast cancer risk conducted by epidemiologists at the University at Buffalo indicate that premenopausal women who usually have more than two drinks per occasion have an 80 percent greater risk of developing breast cancer than women who drink less on each occasion.

The risk is higher even though the total amount of alcohol consumed over a certain period of time is the same.

There was no increase found, however, in risk associated with this drinking pattern in the study's postmenopausal participants.

Jo L. Freudenheim, Ph.D., professor and interim chair of the Department of Social and Preventive Medicine in UB's School of Public Health and Health Professions, presented the results today (June 12) at the Society for Epidemiologic Research meeting being held in Atlanta June 11-14.

"It is well established that alcohol consumption increases the risk of breast cancer, approximately a 10 percent increase in risk for each increase in drink-per-day," said Freudenheim. "However, little is known about the effect of the number of drinks per occasion on risk.

"In our study, if a woman had five alcoholic drinks a week, the effect on breast cancer risk was greater when the drinks were consumed on one or two occasions than if she had only one drink on any one day," Freudenheim said. "We are not sure why there was this difference, but it could be that the higher alcohol load at one time taxes the body's ability to handle alcohol's potentially toxic effects."

This risk factor also may be linked to genetic differences in how alcohol is handled in the body, she noted. UB epidemiologists were the first to show, in results reported in 1997, that premenopausal women with a fast-acting form of an alcohol-metabolizing enzyme who have at least two drinks a day have three times the risk of developing breast cancer compared to lighter drinkers with the fast-acting form, or those with the slow-acting form.

The current study involved 1,120 women with confirmed breast cancer and 2,240 healthy controls matched to those with cancer by age and race. All participants were between the ages of 35 and 79 and were living in Western New York. The study was conducted from 1997-2001.

All participants answered questions posed by trained interviewers on lifetime alcohol consumption, including how often they drank, how many drinks they usually had per occasion, and what type of beverage they drank during their entire lives.

Premenopausal women who drank alcohol during the past 10 years had a greater risk of breast cancer than those who didn't consume alcohol, results showed, findings consistent with a large number of other studies, Freudenheim noted.

In addition, drinking pattern, how the alcohol was consumed, and, in particular, having more than two drinks at a time, also significantly increased breast cancer risk.

"These results need to be considered preliminary," Freudenheim said. "Research of this kind needs to be repeated in different populations with different studies before any conclusions can be drawn. However, if they continue to hold up, we will be able to inform women that not only how much they drink in total, but how much they drink at a time is important."

Also contributing to the study were Jing Nie, doctoral student, and Paola Muti, M.D., associate professor, both in the Department of Social and Preventive Medicine; Maurizio Trevisan, M.D., professor and interim dean in the UB School of Public Health and Health Professions; Tom Nochajski, Ph.D., associate professor in the UB School of Social Work, and Marcia Russell, Ph.D., principal investigator in UB's Research Institute on Addictions.

The study was funded by a grant from the Department of Defense Breast Cancer Research Program.