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When I learned that the U.S. Preventive Services Task Force once again changed its recommendation for when women should begin screening for breast cancer — this time recommending women start at age 40 rather than 50 — I had just finished operating on a 48-year-old African American woman with aggressive breast cancer. My patient had presented to doctors with a painful lump. She didn't think she needed a mammogram for another two years.
There's long been variability in mammography recommendations among various professional medical organizations, which has created confusion for patients. In 2009, the task force increased the age of routine mammograms from 40 to 50, out of concern that earlier screenings were leading to too many false positives and unnecessary imaging tests and biopsies in younger women. Other groups like the American Cancer Society say women ages 40 to 44 should choose screening if they want it, but women should get mammograms every year from ages 45 to 55, after which they can continue screening yearly or every other year.
Part of the reason for the divergence in recommendations stems from an ongoing debate regarding the potential for false positives. These recommendation changes have also become a flashpoint in an even larger debate around overdiagnosis and overtreatment of cancer in the United States.
The earlier we look for cancers, the more we will discover. Screenings can also find lumps, masses and cysts that are not cancerous, resulting in biopsies and follow-up procedures that can cause immense stress for patients. This can happen more often for younger women, because cancer is more common as they get older. In the U.S., the median age at the time of breast cancer diagnosis is 62, and only about 9% of all new breast cancer cases in the U.S. are among women under 45.
We have also learned over time that not all breast cancer tumors grow or spread at the same rate. Almost all breast cancer requires some form of treatment, but some cancers, especially very early ones, may never pose a threat to a person's life. Some of these breast cancers might get excessive treatment relative to their potential for harm. For example, a type of breast cancer that I've studied, called ductal carcinoma in situ — also known as stage 0 breast cancer — may never progress to invasive disease in a person's lifetime, and so may require less therapy. In some cases a patient may just need observation or medication.
I've dedicated much of my academic career to researching breast cancer overtreatment — the idea that some women will undergo invasive surgeries, radiation or chemotherapy that they didn't ultimately need. But while many critics of earlier screening connect it to the issue of overtreatment, I argue that there is a missed nuance here. There is a difference between getting overly aggressive treatment for cancer and not being diagnosed — or not being diagnosed at a point when the options could be less severe.