Purpose of review: Overdiagnosis has become a major problem in medicine in general and cancer in particular. This is a summary of this problem.
Recent findings: Because of earlier detection, the nature of cancer has changed, from a disease usually diagnosed at a late and incurable stage to a heterogeneous condition that varies from clinically insignificant to rapidly aggressive. Screening programs for cancer have resulted in a dramatic increase in the diagnosis of clinically insignificant disease, balanced by improved survival and mortality because of significant cancers being diagnosed at a more curable stage. Overdiagnosis requires the presence of microfocal disease and a screening test to identify this. This exists for breast, prostate, and thyroid cancers, and to a lesser degree for renal and lung cancer. The problem of cancer overdiagnosis and overtreatment is complex, with numerous causes and many trade-offs. It is particularly important in prostate cancer, but is a major issue in many other cancer sites. Screening for prostate cancer appears, based on the best data from randomized trials, to significantly reduce cancer mortality.
Summary: Reducing overtreatment in patients diagnosed with indolent disease is critical to the success of screening.