Hundreds of studies have shown that you’re more likely to get breast cancer if you drink alcohol, but scientists are still working to understand exactly why.
Researchers believe it could raise the levels of hormones (like estrogen) linked to breast cancer or that alcohol damages the genetic material (DNA) in cells. But it isn’t clear if it’s the alcohol itself that causes this. There are many things that can affect your chances of getting breast cancer: diet, exercise, age at first pregnancy, smoking, and race among them. It can be hard for scientists to separate these things from alcohol’s effects.
Another thing to keep in mind is that most of the research has been observational studies. This means that scientists look at facts and draw conclusions. It’s not based on data from experiments that can be repeated.
Does the Amount of Alcohol Make a Difference?
In general, studies have found that the more you drink regularly over time, the higher your chances of having breast cancer. If you’re a woman and you have three drinks per week, your odds are 15% higher than a woman who doesn’t drink at all. And this risk goes up an estimated 10% for each extra drink per week.
But what exactly is a drink? In the U.S., a “standard” drink is defined as about 14 grams of alcohol. This is equal to:
- 1.5 ounces (a shot) of liquor
- 5 ounces of wine
- 12 ounces of beer
But everyone is different. Your individual risk may be higher or lower because of your genes, your race, if you’ve ever been pregnant, if you’ve been exposed to chemicals, and many other things.
If You’ve Already Had Breast Cancer
If you’ve already had breast cancer, there’s still a risk linked to drinking. One study found that three to four drinks per week might make it more likely that your cancer will come back, especially if you’re very overweight or have already gone through menopause.
Alcohol, Breast Cancer, and Men
Breast cancer in men is usually linked to changes in your genes (the doctor will call them mutations). But alcohol could raise the odds, too. Researchers think this may have to do with the way alcohol damages your liver so it can’t balance the level of sex hormones in the body. The levels of male hormones (androgens) go down, and levels of the female hormone estrogen go up. Estrogen helps both normal and cancerous breast cells grow.
While there hasn’t been as much research on breast cancer in men, one study found that having up to about four alcoholic drinks per day raises a man’s chances of getting breast cancer by about the same amount that it does a woman’s chances. The odds go up sharply at amounts greater than about six drinks per day.
Beyond Breast Cancer: Alcohol and Health
Anything more than moderate drinking (no more than one drink a day for women) could take a toll on your health. It can also cause other serious health problems. Drinking is linked to several other forms of cancer, including mouth, throat, liver, and colon. It can damage your heart, liver, kidneys, brain, and even your unborn child if you’re pregnant. It can also play a part in accidents, relationship problems, violence, and mental health issues like depression.