Great health news about coffee is no longer a jolt to the system. So we weren’t surprised to read a new study about coffee and breast cancer that showed protection.

This one looked at more than 1,000 Swedish women who were already being treated for breast cancer. It found that women who drank more than two cups a day tended to have smaller tumors, and a lab component of the study reported that caffeine and caffeic acid (another coffee component) suppressed the growth of breast cancer cells in test tubes.

So should you drink more coffee—or start drinking coffee—to prevent or treat breast cancer? One study alone isn’t enough to go on. To get the bigger picture, we went to Donald Northfelt, MD, a professor of medicine and oncologist at the Mayo Clinic in Scottsdale, Arizona, who has extensive experience in breast cancer research.


While small studies such as the new one from Sweden are part of the picture, Dr. Northfelt suggested a better approach. Look at a recent meta-analysis that pooled data from 37 studies with nearly one million women—including 59,000 with breast cancer. Such studies can use the power of statistics to suggest conclusions that can’t be teased out of any one study.

While there was no overall effect of coffee or caffeine on breast cancer risk, either positive or negative, the larger analysis did find that coffee was protective for postmenopausal women. For them, breast cancer risk declined by about 2% for each two cups of coffee daily.

To put that in perspective, walking briskly for an average of 75 to 150 minutes a week may reduce breast cancer risk by 18%, while drinking two to five alcoholic drinks a day may increase risk by 50%, according to the American Cancer Society. So the risk reduction associated with drinking coffee in postmenopausal women was slight, in comparison.

But still—reducing risk is a good thing, especially when it involves something you may actually enjoy doing. If you like coffee and are concerned about breast cancer, go ahead and pour yourself a few cups—or more. If you’ve been through menopause, it might protect you—a little. Plus, there are a whole host of other health benefits. Regular coffee drinking reduces the risk for diabetes, cardiovascular disease, cognitive decline, Parkinson’s Disease, liver cancer and less life-threatening conditions such as tinnitus (ringing in the ears) and migraines. A coffee habit may even lead to longer life.

No beverage is perfect, of course—even coffee. If you have fibrocystic breasts, which can be lumpy, tender and sore, caffeine (from any source) may make symptoms worse. “It can induce discomfort and greater lumpiness in the breasts, especially at certain times in the menstrual cycle,” says Dr. Northfelt. The good news is that having fibrocystic breasts is entirely benign and doesn’t increase the risk for breast cancer. To get all the pros and cons of drinking coffee, see Bottom Line’s Coffee: The Good News…and the Bad News.