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Last month a study by doctors at Kaiser Permanente led to the following, among dozens of similar, headlines around the world:

“3 drinks a day raises breast cancer risk - All types of alcohol linked to increase in disease, researchers find” (MSNBC).

“New study shows alcohol intake increases the risk for breast cancer” (Today Show)

“Wine, Beer, Spirits Boost Breast Cancer Risk Equally - Three or more drinks a day raise odds by 30%, study finds” (US News and World Report).

Almost all of the news reports focused on the increase in relative risk, which inevitably sounds scary as it appears to be a large percentage increase.  U.S. News also cited oncologist Dr. Yan Li, the lead author of the study on what the absolute increase in risk meant.

“In the general population, the lifetime risk of getting breast cancer is one in eight women, Li said. Based on the study findings, however, "if you drink three or more drinks a day, that risk -- rather than one in eight -- will be one in six," she said.”

That estimate masks large differences between different subgroups and ages and their risk factors, which includedpersonal history of breast abnormalities, current age, age at first menstrual period, age at first live birth, breast cancer history of close relatives, whether a woman has had a breast biopsy, obesity, physical inactivity, and race.

The New York Times’ Tara Parker-Pope (recently arrived from the Wall Street Journal) takes a look at the numbers, which broadly agree with other studies, and finds that the absolute risk is much lower:

“A pooled analysis by Harvard researchers of six studies on alcohol and breast cancer shows that a woman’s risk increases by about 9 percent for every 10 grams of alcohol a day that she drinks. In the United States, a typical drink delivers about 12 grams to 14 grams of alcohol. That means just two drinks a day might increase a woman’s risk for breast cancer by 27 percent. That’s about the same increase associated with long-term use of estrogen or smoking a pack a day of cigarettes.

But before you panic, remember these scary percentages translate into very small risks for the individual woman. A typical 50-year-old woman has a five-year breast cancer risk of about 3 percent. If her risk jumps by 30 percent, her individual risk is still only about 4 percent.”

Parker-Pope also notes that this risk also has to be balanced out by the potential benefits to drinking alcohol in moderate quantities.

To gauge your risk for breast cancer, the National Cancer Institute has created an online risk calculator.

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