Balancing mammography's benefits and harms

Are we overdiagnosing breast cancer?

Cancer screening is intuitively appealing. Common sense would dictate that early detection is good. If you had a silent, potential-life-threatening cancer, wouldn't you want to know as early as possible, when treatment might have the greatest chance of cure? Many would say, “Of course!” Some are even willing to pay a lot of money to have whole-body cancer screening with computed tomography—all for the sake of early detection.1

Enthusiasm for cancer screening, however, may be based on misperceptions about the natural history of cancer and the benefits of early detection (see box). Indeed, some cancers may grow so slowly that they are unlikely to be diagnosed during one's lifetime, and others may regress. Detection of such cancers by screening, overdiagnosis, can lead to unnecessary, invasive treatment.

Overdiagnosis is thought to occur frequently in prostate cancer and neuroblastoma screening.2,3 While concerns have been raised about overdiagnosis of ductal carcinoma in situ (DCIS) with screening mammography,4 little is known about the extent of …