Nov. 21, 2002 -- Women who drink alcohol and take hormone replacement therapy may be doubling their risk of developing breast cancer, according to new findings from the large, ongoing Nurses Health Study.
Researchers found that postmenopausal women who drank at least 1.5 alcoholic beverages a day had a 30% increase in breast-cancer risk compared to women who did not drink. A similar increased risk was seen in women who took hormone replacement therapy (HRT) for five years or longer. Women who took HRT for more than five years and consumed alcohol, the risk of developing breast cancer was nearly doubled.
"Right now a lot of women are wondering whether to take hormone replacement therapy or not," lead author Wendy Y. Chen, MD, of Boston's Brigham and Women's Hospital, tells WebMD. "This research suggests that postmenopausal women who do take it can reduce their risk of breast cancer by modifying their alcohol consumption."
The Nurses Health Study is one of the longest-running major women's health investigations ever undertaken. For this research, Chen and colleagues evaluated survey data collected every two years between 1980 and 1994 from 44,187 postmenopausal women. During the survey period 1,722 of the women were diagnosed with breast cancer.
The study was unique, Chen says, because it tracked alcohol consumption over time, instead of looking at a one-time snapshot of drinking habits. She adds that the findings do not necessarily conflict with studies showing that moderate alcohol consumption reduces heart attack and stroke risk.
"This study found no significantly increased risk of breast cancer in women who consume an average of less than one alcoholic drink per day," she says. "The literature suggests that this is the range at which you get the cardiovascular benefits. You don't need to drink three glasses of wine a night, and you probably shouldn't."
Debbie Saslow, PhD, of the American Cancer Society (ACS), agrees and adds that the increase in breast cancer risk is small even for heavy drinkers.
"For women who chose to drink, we urge them to drink moderately," she says. "Most people probably don't drink more than two drinks a day, every day, and those who do probably aren't thinking about their cancer risk."
Saslow, who is the ACS director of breast and gynecologic cancers, says the Society has been warning women to limit their use of HRT for some time. Until recently, millions of postmenopausal women were on long-term hormone therapy to reduce their risk of cardiovascular disease. But widely reported findings published last summer suggest that the combination of estrogen plus progesterone actually increases the risk of heart attack and stroke, as well as breast cancer.
In this study, only about 10% of the women surveyed were on the estrogen plus progesterone combination. The rest were on estrogen alone.
"Surely in the future fewer women will be on hormone therapy for anything approaching five years, but there will still be women who need to take it long-term for debilitating symptoms of menopause," she says. "We aren't saying that a woman should never take it that long, but that she has to weigh the potential risks and benefits."