July 2017; Vol. 27(3):e2731722 https://doi.org/10.17061/phrp2731722 www.phrp.com.au Perspective What is overdiagnosis and why should we take it seriously in cancer screening? Stacy M Cartera,c and Alexandra Barrattb a Centre for Values, Ethics and the Law in Medicine, University of Sydney, NSW, Australia b Sydney School of Public Health, University of Sydney, NSW, Australia c Corresponding author:
[email protected] Article history Abstract Publication date: July 2017 Overdiagnosis occurs in a population when conditions are diagnosed correctly Carter SM, Barratt A. What is overdiagnosis but the diagnosis produces an unfavourable balance between benefts and and why should we take it seriously in harms. In cancer screening, overdiagnosed cancers are those that did not cancer screening? Public Health Res Pract. need to be found because they would not have produced symptoms or led to 2017;27(3):e2731722. premature death. These overdiagnosed cancers can be distinguished from false https://doi.org/10.17061/phrp2731722 positives, which occur when an initial screening test suggests that a person is at high risk but follow-up testing shows them to be at normal risk. The cancers most likely to be overdiagnosed through screening are those of the prostate, Key points thyroid, breast and lung. Overdiagnosis in cancer screening arises largely from the paradoxical problem that screening is most likely to fnd the slow-growing • An overdiagnosed cancer is correctly or dormant cancers that are least likely to harm us, and less likely to fnd the diagnosed but would not have produced aggressive, fast-growing cancers that cause cancer mortality.