OAKLAND – Moderate consumption of alcoholic beverages (at least three to four drinks per week, no matter the type of alcohol) is associated with a 30 percent increased risk of breast cancer recurrence, according to a new Kaiser Permanente study.

Post-menopausal or overweight women may be most susceptible to the effects of alcohol on recurrence, according to the researchers.

Detailed results of this study will be presented December 9-13 at the Cancer Therapy & Research Center – American Association for Cancer Research San Antonio Breast Cancer Symposium by Marilyn L. Kwan, Ph.D., staff scientist in the Kaiser Permanente Division of Research in Oakland, Calif.

"Women previously diagnosed with breast cancer should consider limiting their consumption of alcohol to less than three drinks per week, especially women who are postmenopausal and overweight or obese," Kwan said.

While previous research has shown that consumption of alcohol is associated with an increased risk of breast cancer, there have been limited studies about alcohol's role in patient prognosis and survival among those already diagnosed with breast cancer.

Kwan and her colleagues examined the effects of alcohol on cancer recurrence and mortality in the Life After Cancer Epidemiology Study, a prospective cohort study of 1,897 breast cancer survivors diagnosed with early-stage invasive breast cancer between 1997 and 2000.

The researchers recruited participants from the Kaiser Permanente Northern California Cancer Registry and compared breast cancer recurrence in women previously diagnosed with breast cancer who drank with a reference group of women previously diagnosed with breast cancer who did not drink.

Researchers used a questionnaire to document information on wine, beer and liquor consumption over the past year. Each year, participants also completed information on health outcomes, including recurrence of breast cancer, which was then verified by their medical records.

After eight years of followup, Kwan and colleagues found 349 breast cancer recurrences and 332 deaths from cancer and other causes. Among drinkers (50 percent of the study population), wine was the most popular choice of alcohol (90 percent), followed by liquor (43 percent) then beer (36 percent).

The increased risk of recurrence appeared to be greater among participants who were postmenopausal and overweight or obese, and was present regardless of type of alcohol. Alcohol consumption was not associated with overall mortality.

"These results can help women make more informed decisions about lifestyle choices after a diagnosis of breast cancer," Kwan said. She added that these findings should be confirmed with more research because few studies have addressed the influence of alcohol on breast cancer prognosis, and the increased risk of recurrence was observed in only some subgroups.

Additional researchers on the study include Erin Weltzien, Emily Tam, Adrienne Castillo, Lawrence Kushi and Bette Caan, all with the Kaiser Permanente Division of Research; and Carol Sweeney, with the division of clinical epidemiology and department of internal medicine at the University of Utah. Funding for the study was provided by the National Cancer Institute.