Overdiagnosis in Breast and Prostate Cancer Screening: Concepts, Methods, and Mistakes

• Activity Number: 459
• Type: Invited
• Date/Time: Wednesday, August 7, 2013 : 8:30 AM to 10:20 AM
• Sponsor: SSC
• Author(s): Ruth Etzioni*+ and Roman Gulati and Leslie Mallinger and Jeanne Mandelblatt
• Companies: Fred Hutchinson Cancer Research Center and Fred Hutchinson Cancer Research Center and Fred Hutchinson Cancer Research Center and Georgetown University
• Keywords: cancer screening ; lead time ; incidence

Abstract

Knowledge of the likelihood that a screen-detected case of cancer has been overdiagnosed is important in making treatment decisions and developing screening policy. An overdiagnosed case is an excess case detected by screening. The problem of overdiagnosis has been long recognized in the case of prostate cancer but has only recently become prominent in breast cancer. Estimates of the frequency of overdiagnosis vary greatly. This presentation will identify features of screening studies that affect estimates of overdiagnosis. First, there are different ways to define and measure overdiagnosis. Second, contextual features including background incidence, screening protocols and compliance can affect study findings. Third, estimation approach is critical. Many studies use excess incidence as a proxy for overdiagnosis. Others use statistical models to make inferences about lead time and then derive the corresponding fraction of cases that are overdiagnosed. I will review both approaches and demonstrate why they produce different results. Finally I will illustrate how we have used modeling to personalize estimates of overdiagnosis for use in clinical decision making in prostate cancer.