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Studies examine the link between drinking alcohol and increased breast cancer risk in women

A woman holds a glass of red wine to the camera. You can't see the woman's face.

If you drink with any degree of regularity — or even at all — you might want to reconsider. Numerous studies point to alcohol increasing the risk of breast cancer.

Dr. Nisha Unni is a breast cancer specialist with Parkland Health and Hospital System and an Assistant Professor in the Internal Medicine Department of UT Southwestern Medical Center.
She talked with KERA’s Sam Baker about the ties between alcohol and breast cancer.


What does alcohol have to do with breast cancer?

Alcohol is a common term that we use for ethanol or ethyl alcohol, the chemical substance that we find in alcoholic beverages like wine, beer, distilled spirits.

The exact mechanism by which alcohol increases the risk of breast cancer is not fully known, but there are different hypotheses:

The most common one is that ethanol is metabolized or broken down into a substance called acetaldehyde is a carcinogen. It's a substance that causes cancer by damaging DNA, which is a genetic material and proteins, um, in breast cancer.

Alcohol also increases the blood levels of estrogen, which is a sex hormone. That's linked to increase risk for estrogen receptor positive or hormone receptor positive breast cancer — the most common type of breast cancer that we see.

Another theory is that alcohol impairs the body's ability to break down or absorb a variety of nutrients like folate, vitamin A, vitamin D, all those good things.

Alcohol also provides a lot of empty calories, which can cause weight gain, and we know weight gain increases the breast cancer risk.

How much of a risk is alcohol for breast cancer?

Data from more than 100 observational studies indicate even light drinkers — women who drink less than one drink per day — have a slightly increased risk of developing breast cancer compared to non-drinkers, which comes to about 5%.

So if a woman drinks about an average of one drink per day, her risk of breast cancer increases by 7 to 14%. If it's two to three drinks per day, this risk goes up to 25%, which is a big number.

We say that in the United States, 1 in 8 women develop breast cancer over their lifetime, which by itself is a big number. And alcohol increases this risk.

But the U.S. Dietary Guidelines say one drink a day for women is OK.

That is what is commonly recommended. The safest option is always not to drink or abstinence, but that's not always practical.

The next best thing to do is to limit or minimize the amount of alcohol intake to the extent possible. Social use of alcohol intermittently is OK, but that also does not mean that you should binge drink because there are studies that have shown that binge drinking is associated with increased risk of breast cancer compared to steady drinkers.

Do other factors determine whether alcohol is likely to affect breast cancer?

There is no one thing that causes or leads to breast cancer. It is a multifactorial reason, and there are non-modifiable risk factors like being female, our age, family history, genetics, which we cannot modify. And then there are modifiable risk factors like diet, exercise, and alcohol intake which we can modify or control.

Do health professionals discuss alcohol and breast cancer much with patients?

I would argue no. We always ask about smoking with every visit, but there should be more awareness among women on the potential risk of alcohol use and increased association with breast cancer.

And I have seen a few social media campaigns that come up with this topic in mind, and I would argue that it's not enough. There needs to be more awareness and education.


Drinking Alcohol

Alcohol and breast cancer risk: What to know

Alcohol Intake and Breast Cancer Risk: Weighing the Overall Evidence

National Cancer Institute: Alcohol and Cancer Risk

Sam Baker is KERA's senior editor and local host for Morning Edition. The native of Beaumont, Texas, also edits and produces radio commentaries and Vital Signs, a series that's part of the station's Breakthroughs initiative. He also was the longtime host of KERA 13’s Emmy Award-winning public affairs program On the Record. He also won an Emmy in 2008 for KERA’s Sharing the Power: A Voter’s Voice Special, and has earned honors from the Associated Press and the Public Radio News Directors Inc.