The Women's Health Resource. On the web since 1997.

Daily alcohol consumption may increase breast cancer risk (dateline December 7, 1999)

The results of a study published in The Journal of the American Medical Association reveal that women who drink alcohol are at higher risk of developing breast cancer compared to nondrinkers. In the largest study on alcohol and breast cancer ever conducted, researchers analyzed data from 322,647 women (including 4,335 women who had breast cancer) in Canada, The Netherlands, Sweden, and the United States. Women who consumed two to five alcoholic beverages each day were found to have a 41% increased risk of developing invasive breast cancer compared to women who do not drink.

The study was led by Stephanie Smith-Warner, PhD of the Harvard School of Public Health in Boston. According to Smith-Warner, any regular alcohol consumption increases a woman’s risk for breast cancer. For every 10 grams (g) of alcohol a woman consumes, her risk of breast cancer increases by 9%. Women who consume 30g to 60g of alcohol per day increase their risk of breast cancer by 41%. 30g to 60g of alcohol is equivalent to 2.3-4.5 bottles of beer, 2.8-5.6 glasses of wine, or two to four shots of liquor.

Alcohol and Breast Cancer

Amount of Alcohol Per Day

Increased Breast Cancer Risk

10g   (0.75 to 1 drink) 9%
30g-60g  (2 to 5 drinks) 41%

The reduction of regular alcohol consumption is likely to reduce a woman’s risk of breast cancer, said Smith-Warner. However, numerous studies over the last decade have found that women who consume one to two glasses of wine each day may decrease their risk of cardiovascular disease. Though Smith-Warner does not object to these results, she notes that patients may lower their cardiovascular disease risk by engaging in other behaviors such as eating healthy foods and exercising regularly instead of drinking alcohol.

Though Smith-Warner’s study needs further confirmation, other health care providers believe the findings are valid. Dr. Maurizio Trevisan, MD, chair of social and preventive medicine at the State University of New York at Buffalo (SUNY) calls the results substantial. Reducing alcohol consumption is a modified behavior women may practice to lower their risk for breast cancer. Alcohol is also known to increase the risk of cancers of the mouth, throat, and esophagus.

Smith-Warner and her colleagues are quick to point out that the results of their study apply to women who consume alcohol on a daily basis as opposed to women who occasionally drink. The researchers plan to focus next on the effects of certain drinking patterns, drinking at a young age, high alcohol consumption, and the specific way(s) in which alcohol may cause breast cancer.

In addition to the consumption of alcohol, other factors that may increase a woman’s risk of developing breast cancer include:

  • Age
  • Family history
  • Previous breast biopsy showing benign conditions
  • Menstruation beginning at an early age
  • Menstruation continuing past age 50
  • Not having children
  • Having a first child after age 30
  • High fat diets
  • Obesity
  • Mutations of the genes, BRCA1 and BRCA2

Additional Resources and References