According to a new report published in the November 2 issue of JAMA, women who consume between three to six alcoholic drinks per week have a small increase in the risk of breast cancer. Furthermore, consumption of alcohol in both earlier and later life is also connected with an increased risk.
Background information in the report states:
"In many studies, higher consumption of alcohol has been associated with an increased risk of breast cancer. However, the effect of low levels of drinking as is common in the United States has not been well quantified. In addition, the role of drinking patterns (i.e., frequency of drinking and 'binge' drinking) and consumption at different times of adult life are not well understood."
In order to assess the connection between breast cancer and alcohol intake during adulthood, including frequency, age of consumption and quantity, Wendy Y. Chen, M.D., of Brigham and Women's Hospital and Harvard Medical School, Boston, and her team conduced an investigation that consisted of 105,986 women enrolled in the Nurses' Health Study. Participants were followed up from 1980 until 2007 with an early adult alcohol evaluation as well as 8 updated alcohol assessments. The main outcome measured by the investigators was the risk of developing invasive breast cancer.
The team discovered that 7,690 women among the study participants were diagnosed with invasive breast cancer during the follow-up period. Evaluation of data indicated that although modestly, low levels of alcohol intake (5.0 to 9.9 grams each day, equivalent to 3-6 glasses of wine per week) were statistically considerably linked with a 15% increase of developing the disease. They also found that the increased risk of breast cancer for those who drank at least 30 grams of alcohol per day on average (at least 2 drinks daily) was 51% compared to women who never drank alcohol.
In addition, when they assessed alcohol consumption levels between the ages 18 to 40 and after the age of 40, they discovered that both were strongly linked with an increased risk of breast cancer. The connection between early adulthood and alcohol consumption still remained even after controlling for alcohol consumption after the age of 40.
Furthermore, they also found that binge drinking, although not frequency, was linked with breast cancer risk after they controlled for cumulative alcohol consumption.
According to the researchers, while the specific mechanism for the connection between breast cancer and alcohol remains unknown, one likely reason may involve the way alcohol effects the circulation of estrogen levels.
"In summary, our study provides a comprehensive assessment of the relationship between alcohol intake and breast cancer risk in terms of timing, frequency, quantity, and types of alcohol in a large prospective cohort with detailed information on breast cancer risk factors. Our results highlight the importance of considering lifetime exposure when evaluating the effect of alcohol, and probably other dietary factors, on the carcinogenesis process.
However, an individual will need to weigh the modest risk of light to moderate alcohol use on breast cancer development against the beneficial effects on cardiovascular disease to make the best personal choice regarding alcohol consumption."
In an associated report on the discoveries of this investigation, Steven A. Narod, M.D., of the Women's College Research Institute, Toronto, says this raises and important clinical question:
"Should postmenopausal women stop drinking to reduce their risk of breast cancer?
For some women the increase in risk of breast cancer may be considered substantial enough that cessation would seem prudent. However, there are no data to provide assurance that giving up alcohol will reduce breast cancer risk. Moreover, it would likely be easier for a woman who consumes 1 drink a week to stop drinking than for a woman who consumes 2 drinks a day.
Furthermore, women who abstain from all alcohol may find that a potential benefit of lower breast cancer risk is more than offset by the relinquished benefit of reduced cardiovascular mortality associated with an occasional glass of red wine. Exploration of the risk-benefit relationships between low levels of alcohol consumption and all-cause and cause-specific morbidities and mortalities might be the topic of future analyses of the Nurses' Health Study and other prospective cohort studies."
Written by: Grace Rattue