Rethinking the link between moderate alcohol drinking and breast cancer
Time course and drinking pattern are important for understanding the relationship between alcohol consumption and breast cancer, say scientists at the National Institutes of Health.
Akinso: Young women who binge drink– have four or more drinks per occasion — could be increasing their risk of breast cancer later in life. This is one conclusion of an NIH review of epidemiologic data — epidemiological studies seek to identify patterns, causes, and control of disorders in groups of people.
Brooks: What prompted the study was several large epidemiologic studies that described an association between moderate alcohol consumption and breast cancer in women.
Akinso: Dr. Philip Brooks is a program officer at the NIH.
Brooks: Some of the conclusions to some of the discussion about those studies were quite dramatic. And they were statements suggesting that as result of these studies that no amount of drinking could be considered safe in terms of breast cancer risk.
Akinso: While some evidence has linked even moderate alcohol consumption to an increase in breast cancer risk, other studies have associated low to moderate alcohol intake with reduced risk for cardiovascular problems and other health benefits. To help clarify what could be deemed as mixed messages NIH decided to analyze recent epidemiologic studies of alcohol and breast cancer.
Brooks: Some of the beneficial effects of moderate alcohol drinking are not just based on epidemiologic studies but also backed up by mechanisms from studies in the laboratory. So as a result of this, we sort of wondered about what was actually done in some of these large epidemiologic studies, how are the studies done. We wanted to understand that — how the various conclusions were drawn. Really what we would like to understand is the mechanistic relationship between alcohol consumption and breast cancer risk.
Akinso: Some of the largest epidemiologic studies of alcohol and breast cancer risk involved asking middle-age postmenopausal women about their current alcohol consumption, then assessing breast cancer diagnoses over the next five to 10 years. Because in most cases it takes roughly 20 years or more to go from a normal cell to a clinical diagnosis of cancer, researchers do not believe that the breast cancers diagnosed in women in these studies were caused by alcohol they reported drinking at the beginning of the study. Dr. Brooks explains there are a couple explanations.
Brooks: One possibility with regard to the time course effect is that in some of these studies some of the women might have already had undiagnosed breast cancers. And the drinking they reported could have made those breast cancers grow faster or become more aggressive for example. Another one, though, is that since drinking a life time habit — when you ask a woman about how much she drinks, say at the age of 50, that's related to how much she's been drinking her whole life. And it's possible that the drinking she did earlier in life which related to the breast cancers. And earlier in life the drinking may not have been moderate it may have been more along the binge type drinking.
Akinso: Dr. Brooks adds that a significant problem with alcohol and breast cancer studies has been that people tend to report less alcohol than they actually consume. As a result, such studies can overestimate the effect of a given amount of alcohol on breast cancer risk. Another limitation of these studies is the lack of information about drinking patterns.
Brooks: We really need more solid data on how and when alcohol effects breast cancer risk to allow women to make informed decisions about the overall health impact of moderate drinking indifference changes their lives.
Akinso: Dr. Brooks emphasizes the take home message is that binge drinking is unhealthy for anyone, and the possibility of increasing breast cancer risk is another reason for women in particular to avoid binge drinking. For more information on the link between breast cancer and alcohol, visit www.niaaa.nih.gov. For NIH Radio, this is Wally Akinso – NIH... Turning Discovery Into Health®.
About This Audio Report
Reporter: Wally Akinso
Sound Bite: Dr. Philip Brooks
Topic: Binge, drinking, breast, cancer, alcohol, alcoholism, women