Alcohol

Alcohol appears to increase the risk of breast cancer, with some studies finding a positive correlation between consumption levels and increased risk. One study concluded that breast cancer comprises 60 percent of alcohol-attributable cancers among women. The UK's Review of Alcohol: Association with Breast Cancer concludes that "studies confirm previous observations that there appears to be an association between alcohol intake and increased risk of breast cancer in women. On balance, there was a weak association between the amount of alcohol consumed and the relative risk.

The National Institute on Alcohol Abuse and Alcoholism (NIAAA) concludes that "Chronic alcohol consumption has been associated with a small (averaging 10 percent) increase in a woman's risk of breast cancer. According to these studies, the risk appears to increase as the quantity and duration of alcohol consumption increases. Other studies, however, have found no evidence of such a link.

The UK Committee on Carcinogenicity of Chemicals in Food, Consumer Products Non-Technical Summary concludes, "the new research estimates that a woman drinking an average of two units of alcohol per day has a lifetime risk of developing breast cancer 8% higher than a woman who drinks an average of one unit of alcohol per day. The risk of breast cancer further increases with each additional drink consumed per day. The research also concludes that "approximately 6 percent (between 3.2 percent and 8.8 percent) of breast cancers reported in the UK each year could be prevented if drinking was reduced to a very low level (i.e. less than 1 unit/week)." A review article from JAMA also found that breast cancer incidence seems to increase with increasing alcohol consumption. It has been reported that "two drinks daily increase the risk of getting breast cancer by about 25 percent" (NCI), but the evidence is inconsistent. The Framingham study has carefully tracked individuals since the 1940s. Data from that research found that drinking alcohol moderately did not increase breast cancer risk (Wellness Facts). Similarly, research by the Danish National Institute for Public Health found that moderate drinking had virtually no effect on breast cancer risk.

A 2007 study indicated that consuming one or two alcoholic drinks a day increases the risk of breast cancer by 10 percent compared with those who consumed less than one drink daily. Women who have three or more drinks a day increased their breast cancer risk by 30 percent. The type of drink was not a factor.

One study suggests that women who frequently drink red wine may have an increased risk of developing breast cancer.