It's hard to believe that a one in a hundred risk of something bad happening would generate so much heated debate, but that's where we're at when it comes to the question of mammograms for women in their 40s. Since breast cancer is a disease which risk increases with age, the clear cut off point for mammography has been age 50. Mammography will find cancer in women in their 40s, but will carry a much higher risk of false positives.
Specifically, a 40-year-old woman has a 1.5 percent chance of developing breast cancer at some point during her 40s. The 1-in-8 chance repeated so frequently is over a lifetime -- up to age 80.
While mammography is the best tool we have in detecting breast cancer, it's not a perfect test. Mammograms will pick up abnormalities that are not breast cancer. The problem is that doctors can't say definitively these abnormalities are benign without further testing. Sometimes that means having an additional mammogram, sometimes women must then have a biopsy. In the meantime, many of these women are worrying.
The when-to-start mammography debate has been going on for almost twenty years. More recently, in 2009, the U.S. Preventive Services Task Force re-ignited the debate when it stopped short of making an explicit recommendation that women in their 40's be screened and instead said that the decision was an "individual one."
Today two studies in the Annals of Internal Medicine have some hard data to help individual women make that decision. In a review of 9.5 million mammograms from across the country, researchers say that two groups of women in their 40's are at increased risk of developing breast cancer. These two risks are a close family relative with breast cancer -- a mother, sister or daughter --- and extremely dense breast tissue.
These risk factors put 40-49 year old women at the same risk of developing breast cancer as women in their 50's -- 2.5 percent over the decade-- and researchers say have crossed the "tipping point" where the benefit of mammography outweighs the possible harms of false positives. "The main takeaway," says Dr. Karla Kerlikowske of U.C. San Francisco and a co-author of both studies, "is that we need to move in the direction of what’s been coined 'risk-based screening' where whether you have a mammogram or not is not just based on your age, but based on your overall risk of breast cancer."
But talk to just about any woman and they will tell you of the 40-something they know with breast cancer. Soon enough the discussion becomes very emotional. Dr. Otis Brawley, Chief Medical Officer of the American Society, wrote an accompanying editorial in the Annals addressing maximizing benefits and minimizing harms. "Risk-based screening can refocus efforts onto the women who are most likely to benefit from screening," he writes. "This would not be a reduction in resources used; it would be a more effective use of resources. Risk-based screening has the potential to save more lives than our current practice."
Still, at least for the time-being, the American Cancer Society continues to recommend annual mammograms for women starting at age 40.
Dr. Susan Kutner is Chair of the Northern California Kaiser Breast Care Task Force and was not involved with the studies. She welcomes the new data. "What these articles address is there are some women ages 40-49 who would benefit from screening," she told me. "Personalizing their screening based on their risk is really important, and that's what we're learning as we analyze this data."
KQED's Forum addressed the new research today. You can listen to the program here: