The Limits of Mammograms

woman getting a mammogram

Are mammograms leading to the overdiagnosis of breast cancer? In a recently published study of women in Denmark, up to a third of women who were flagged by mammograms as having cancer either lacked malignant cancer or had slow-growing  cancer that did not need immediate treatment. Also, some more advanced tumors were missed by the screening.

At least part of the overdiagnosis is due to the identification of ductal carcinoma in situ (DCIS); DCIS is sometimes called “stage 0” in breast cancer.  In DCIS, some abnormal breast cells exist, but they have not yet invaded to become a cancer. Because the cells can invade later, DCIS is often treated aggressively.

According to Dr. Otis Brawly, “Some of those pea-sized lesions are not going to kill. Some of those pea-sized lesions are going to regress over time. We are curing people that don't need curing."

Early detection of cancer is critical, and the balance between not screening, and screening with an imperfect test is difficult.

However, Brawley clarifies that this is not a call to abandon mammograms; rather, it is important that physicians understand their limitations.

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