The six numbers that demystify new mammogram rules


The American Cancer Society is out with new guidelines for breast cancer screening. The advice is intended for women who are in good health and have no reason to suspect their risk of getting breast cancer is higher than average.

Here's a by-the-numbers look at what the new guidelines say, and why:


This is the age at which women may start getting annual mammograms to screen for breast cancer. But they don't have to. For a 40-year-old woman, the risk of getting breast cancer is pretty low — only 1.47% of women this age will be diagnosed with the disease by the time they turn 50. So if women are concerned that a test at this age is more likely to prompt a false positive than find a real cancer, they can skip it.


By this age, all women should begin annual mammograms to screen for breast cancer. When it comes to factors like the risk of being diagnosed with breast cancer and the risk of dying of the disease, women ages 45 and 49 are quite similar to women ages 50 to 54, according the American Cancer Society.


At this age, most women have hit menopause and their bodies have scaled back production of the hormones estrogen and progesterone. That makes breast cancer tumors grow more slowly. This and other age-related changes mean that getting a mammogram once every two years will catch almost as many cancers as getting a mammogram annually. Women may opt for less frequent mammograms to reduce their risk of unnecessary tests and treatment.


Until they have this many years of life expectancy left, women should keep on getting mammograms at least once every other year.


This is how many clinical breast exams doctors should perform on their female patients. The American Cancer Society analysis found that when women were already getting mammograms, adding the breast exam to the mix did not help doctors find more breast cancers. However, it can increase the risk of false positives.


The number of times the guidelines mention the importance of considering each woman's "values and preferences" when making decisions about mammograms.


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