Alcohol and Cancer Risk: When Does the Risk Start?

A major new study is calling into question what many women thought they knew about drinking alcohol. The U.K.’s Million Women Study links even low-to-moderate alcohol consumption to increased risk of breast and several other cancers. Most women who drink alcohol in the United Kingdom, as in the United States, drink amounts classified as low-to-moderate, which is within current recommended limits. The study concludes that alcohol accounts for approximately 11 percent of breast cancer cases in the United Kingdom. This is strikingly similar to the conclusions of a policy report released this year by the American Institute for Cancer Research linking 11 percent of breast cancer in the U.S. to alcohol.

The Million Women Study followed 1.3 million middle-aged women for seven years. The large number of women in the study gives its conclusions strength and allowed researchers to compare cancer risk among a range of alcohol intake levels, from occasional to frequent consumption.

For each woman, impact on risk varies with personal and family history, diet and overall lifestyle.

Compared to women who drink no more than two standard drinks per week, seven to 14 drinks per week increased breast cancer risk by 13 percent. Above seven to 14 drinks per week is beyond the one drink per day definition of moderate drinking for women. But even three to six drinks per week—classified as low to moderate–increased risk 8 percent. This rise in breast cancer risk may seem small, but because it is the most common cancer among American women, except for skin cancers, even a small percentage change can affect many women.

In the U.S., one standard drink (5 ounces of wine, 12 ounces of beer, or one-and-a-half ounces of 80-proof spirits) contains 12 to 15 grams of alcohol. This new study found that each additional ten grams of alcohol daily increased women’s risk of cancers of the mouth and throat by 29 to 44 percent. Risk of liver cancer increased 24 percent, esophageal cancer 22 percent and that of breast cancer 12 percent.

The large study size also allowed researchers to look separately at smokers and nonsmokers. Previous research showing an interaction between tobacco and alcohol was clearly demonstrated. The dramatic increase in cancers of the mouth and throat linked to alcohol consumption was strongly tied to smoking, perhaps because alcohol seems to increase the ability of tobacco’s carcinogens to enter and damage cells. Among nonsmokers, alcohol showed little effect on mouth and throat cancers.

Red wine drinkers may have hoped that laboratory studies of an antioxidant compound called resveratrol found in red wine might make it protective. However, this study shows wine is no different than other kinds of alcohol in increasing cancer risk.

The powerful conclusions from this Million Women Study may prompt some women to give up alcohol completely. However, the study also found that women consuming up to two drinks per week showed no significant difference in cancer risk compared to those who identified themselves as nondrinkers.

For each woman, impact on risk varies with personal and family history, diet and overall lifestyle. Some evidence suggests that up to one alcoholic drink per day may be heart-healthy for women. Yet other steps to promote heart health–weight control, daily physical activity and a mostly plant-based diet low in saturated fat–also reduce the risk of cancer. According to AICR’s report, while avoiding alcohol could prevent about 11 percent of breast cancer in U.S. women, regular physical activity and weight control could each prevent 17 percent of cases. In fact, reaching and maintaining a healthy weight could prevent about 20 percent of seven types of weight-related cancers, including breast, pancreatic, and colorectum.

Find more from Karen Collins.

Karen Collins, D.C.N., M.S., R.D., serves as the nutrition advisor to the American Institute for Cancer Research (AICR). Karen writes two syndicated weekly columns, "Nutrition Notes" and "Nutrition-Wise," distributed by AICR. Karen was an expert reviewer for AICR's landmark international report, "Diet, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective," which provides recommendations based on an examination of more than 7,000 research studies by a panel of internationally renowned scientists. (Read her full bio.)

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Provided by American Institute of Cancer Research