Alcohol Consumption And Breast Cancer
It is now more than 30 years ago since the first study linking alcohol consumption to an increased risk for breast cancer in women was reported. Although still a somewhat controversial topic, now well over three decades of extensive research on this subject tend to confirm a consistent finding that breast cancer occurs more frequently in women who consume one or two or more drinks of alcohol per day than in those who do not drink.
One study, in the Journal of the American Medical Association (JAMA), two investigators from the Departments of Food Science and Nutrition, Dr. Singletary, at the University of Illinois, and Dr. Gapster, at Northwestern University Medical School, reviewed the published scientific literature on this matter.
Whereas a few studies failed to confirm this risk for women, the larger studies reported that alcohol intake, independent of any other consideration evaluated, increased the development of breast cancer. In general, the more alcohol consumed, the greater became the risk.
How alcohol consumption increases the risk for developing breast cancer remains speculative. One theory suggests that alcohol intake may adversely effect the absorption or tissue deposition of key cancer-protecting nutrients, especially those found in fruits and vegetables.
In most instances, high levels of alcohol intake are frequently linked to poor nutritional practices. Many individuals who drink excessively, for instance, may have low dietary intakes of folate and other water soluble vitamins known to be important to cancer prevention. Such individuals are also at increased risk for colon and rectal cancers.
Some of the metabolic breakdown products of alcohol, such as acetaldehyde, may alter normal folate metabolism within cells, rendering them susceptible to damage of proteins that can lead to the development of cancer cells.
Alcohol intake has also been associated with decreased concentrations in the blood of beta-carotene, vitamin C and other micronutrients important to cancer prevention. Thus, the potential risk for increased chances of developing breast cancer may be mediated by the effect of alcohol on other non-alcohol dietary nutrients.
Alcohol intake is linked to an increased risk for noncancerous fibroglandular breast densities, seen on precancerous mammograms and the risk for ultimately developing breast cancer. Alcohol intake has also been linked, in at least some studies, to reoccurrence of breast cancer and to the greater development of distant or metastatic breast cancer occurrences.
It is generally accepted that the overall risk for breast cancer in women is proportionate to the accumulative lifetime exposure of the breasts to circulating estrogen. For premenopausal women, alcohol intake has been linked to higher levels of estrogens, as well as the decreased frequency of prolonged cycles and shorter menstrual periods. These latter two considerations are, in turn, associated with higher estrogen levels and thus increased rates of breast cancer.
Alcohol is not considered to be a carcinogen (direct cancer-causing chemical). It may, however, act as a potential co-carcinogen, an agent that promotes or enhances cancer-causing capacity of known cancer-causing agents.
Studies on breast cancer and experimental animals and breast cells grown in tissue cultures have been somewhat inconsistent, but generally these reports have also tended to lend support to the clinical information gathered on humans: alcohol increases the risk for breast cancer.
Thus, some researchers have concluded that the majority of studies on human populations provide consistent evidence for a possible association between alcohol consumption and an increased risk for developing breast cancer in women. The increased risk is not extremely great, but it appears to be real and it is significant.
In some countries, where alcohol consumption is greater than it is in the United States, alcohol intake may account for as much as 15 percent of all breast cancers.
Breast cancer rates are, in general, high. Perhaps most of the risk can be attributed to inherited genetic predispositions and a positive family history of breast cancer.
Alcohol is, nevertheless, one of the few identified risk factors that can be modified or changed to reduce the chances of getting breast cancer. Alcohol use is a personal choice of lifestyle, and its potential perceived or real benefits of using alcohol thus must be weighed against its potential risks.
In particular, investigators have recommended that alcohol abuse or excessive drinking (more than three drinks/day) should be discouraged. For women who are occasional social drinkers (less than an average of one drink/day), there appeared to be no excessive increase in risk to warrant recommending total alcohol abstentia.
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