Although previous research has linked alcohol consumption to an increased risk of developing breast cancer, a new study has found that drinking before and after diagnosis does not impact survival from the disease. In fact, a modest survival benefit was found in women who were moderate drinkers before and after diagnosis due to a reduced risk of dying from cardiovascular disease, a major cause of mortality among breast cancer survivors.
The Public Health Sciences Division's Dr. Polly Newcomb, head of the Cancer Prevention Program, led the study, the results of which appear in the April 8 edition of the Journal of Clinical Oncology.
"Our findings should be reassuring to women who have breast cancer because their past experience consuming alcohol is unlikely to impact their survival after diagnosis," Newcomb said. "This study also provides additional support for the beneficial effect of moderate alcohol consumption with respect to cardiovascular disease."
The study was based on data from almost 23,000 women with breast cancer who participated in the Collaborative Breast Cancer Study, a National Cancer Institute-sponsored, multi-site, population-based study of risk factors for breast cancer, and the largest study of its kind. The study—the largest of its kind—began in 1988 and was conducted in New Hampshire, Massachusetts and Wisconsin. In a smaller follow-up study between 1998 and 2001, about 5,000 study participants with breast cancer also received a follow-up questionnaire about their alcohol consumption habits after diagnosis.
Among study participants with a history of breast cancer, the authors found that the amount and type of alcohol a woman reported consuming in the years before her diagnosis was not associated with her likelihood of dying from breast cancer. However, the authors also found that those who consumed a moderate level of alcohol (three to six drinks per week) in the years before their cancer diagnosis were 15 percent less likely to die from cardiovascular disease than nondrinkers. Moderate wine consumption in particular was associated with a lower risk of cardiovascular disease mortality, while no such benefit was evident for consumption of beer or spirits, or for heavier levels of alcohol consumption.
Similar patterns were evident when considering reported alcohol consumption after breast cancer diagnosis. The amount and type of alcohol a woman consumed after diagnosis did not appear to be associated with survival of breast cancer, but those who consumed alcohol in moderation experienced a 40 percent to 50 percent lower mortality rate from cardiovascular disease.
Alcohol consumption is believed to influence breast cancer risk through increases in estrogen production in both pre- and post-menopausal women. What could account for the difference in alcohol's impact on risk of developing breast cancer and on survival from the disease? "It could be that the kind of breast cancer that is more likely to be diagnosed among women who drink may be more responsive to hormone-modifying therapies," Newcomb said.
The National Cancer Institute and Komen for the Cure funded the study. Co-authors include Michael Passarelli of PHS and researchers from the University of Wisconsin Paul B. Carbone Comprehensive Cancer Center, Wageningen University in the Netherlands, H. Lee Moffitt Cancer Center, Norris Cotton Cancer Center, the University of North Carolina Lineberger Cancer Center and Research Institute, and Harvard Medical School and Brigham and Women's Hospital.