Alcohol and Breast Cancer

Breast cancer is the most common alcohol-associated cancer in women, according to the Centers for Disease Control and Prevention (CDC). Yet half of Americans are unaware that alcohol is a risk factor for cancer. 

“All alcoholic beverages have ethanol, which is a known carcinogen or cancer-causing agent,” says Amy Comander, MD, a breast oncologist at the Mass General Brigham Cancer Institute. The American Cancer Society (ACS) ranks alcohol use as a top preventable cause of cancer—just after smoking and obesity.

The link between alcohol and breast cancer is especially worrisome. Research suggests alcohol causes about 4 in 25 of all breast cancers. And breast cancer accounts for more than half of alcohol-related cancer deaths in women. The overall cancer risks are so great that the former U.S. Surgeon General recommended cancer warning labels for alcoholic products like those on tobacco products.

How does alcohol increase breast cancer risk? 

The negative health impacts of alcohol are numerous. When it comes to breast cancer, alcohol may play a role by affecting:

• Cells and DNA: Your body makes a toxic chemical called acetaldehyde, as well as unstable molecules called free radicals, when you drink. These substances damage cells, tissues, and the genetic makeup of cells (DNA). Damaged cells can become cancerous and grow out of control.
• Hormones: Hormones, especially estrogen, rise when you drink alcohol, which increases breast cancer risk. High hormone levels are especially concerning if you have, or are at risk for, hormone receptor-positive breast cancers.
• Nutrient levels: Alcohol affects how well your body absorbs nutrients like folate. This B vitamin helps your body make DNA and supports the growth of healthy cells. Low folate levels may increase breast cancer risk.
• Weight: A 5-ounce glass of cabernet sauvignon has about 125 calories. While that’s slightly fewer calories than a small bag of potato chips, the nutritional value (zero) is the same. Plus, you might think twice about opening another bag of chips but not hesitate to refill a wine glass. Consuming too many empty calories can cause weight gain and obesity, which causes cell inflammation linked to breast cancer.

Is there a “safe” amount of alcohol to drink?

Unfortunately, there’s no such thing as a “safe” amount of alcohol. In terms of preventing cancer, the safest guidance according to the ACS and other organizations is to not drink alcohol. To minimize health risks, women who choose to drink should have one drink or less per day (no more than 7 drinks per week). Depending on the alcohol by volume (ABV), one drink is equal to a 5-ounce glass of wine, 12-ounce beer, or 1-ounce shot of liquor. Your risk of breast cancer goes up the more you drink.

Binge drinking and breast cancer risk

Holding back during the week so you can drink more during the weekend also isn’t a good idea. Studies associate binge drinking (defined as four or more drinks in one sitting for women) with up to a 50% increase in lifetime breast cancer risk compared to women who drink in moderation. “We need more research, but binge drinking may be contributing to the rise in the number of younger women developing breast cancer,” says Dr. Comander. 

Is there a “safe” type of alcohol?

Your choice of beverage doesn’t make a difference. You might have heard that red wine is good for your heart, but don’t be fooled by its so-called “health halo,” cautions Dr. Comander. “Your body metabolizes the ethanol in red wine and a shot of tequila in the same way,” she says.

Tips for drinking responsibly and lowering breast cancer risk

While there may not be a safe amount of alcohol, Dr. Comander recognizes that drinking responsibly and in moderation is generally OK. From her perspective as a breast cancer specialist, she advises limiting alcohol intake. “I recommend no more than three drinks per week—and preferably not all at once,” she says.

Women with high risk factors may need to pay more attention to how much they drink. This includes women who:

• Are getting, or have completed, treatment for breast cancer
• Have a family history of breast cancer or known gene mutation
• Have a history of smoking or alcohol use disorder
• Have another type of cancer
• Have other risk factors, such as obesity
• Take hormone replacement therapy

“Think before you drink” is a good rule of thumb. “Be mindful of how much you’re drinking and why,” says Dr. Comander. For instance, if you’re in the habit of drinking red wine every night while making dinner or to unwind, look for healthier alternatives. If you’re planning to drink with friends on Saturday, cut back during the week. “Fortunately, the growing popularity of nonalcoholic beverages and mocktails makes it easier than ever to socialize while still looking out for your health,” says Dr. Comander.