Cancer Knowledge Network

Overdiagnosis, Overdone: A Patient Summary

by Constantine Kaniklidis *, Research Director, No Surrender Breast Cancer Foundation (NSBCF) **

Understanding – and Measuring – Overdiagnosis  Overdiagnosis occurs when the patient, were it not for screening, would have died of some other non-cancer cause without ever having been diagnosed with malignancy. Overdiagnosis estimates are fraught with many complex limitations and challenges, but overdiagnosis estimates can be “normalized” by drawing on only studies restricted to actual screening-attendant women (as opposed to only screening-invited women) and which also control for the major known confounding factors. The EUROSCREEN review (2 million women age 50 or older in 18 countries) which met these requirements found overdiagnosis as being just 6.5%, and autopsy studies find only a small degree of overdiagnosis (under 10% total, just 1.3% for invasive breast cancers only).

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Overdiagnosis, Overdone: Unraveling Issues and Pitfalls

by Constantine Kaniklidis *, Research Director, No Surrender Breast Cancer Foundation (NSBCF) **

Overdiagnosis Estimates

In a previous editorial on the mammography debate, I wrote: “that it is complex; that it is naïvely implausible to expect any decisive final resolution to the residual issues that will be convincing to the principle contending parties; and that behind it all, the devil is in the methodology”¹. Almost two years later, the words stand true, but we have advanced significantly in illuminating the many dark cobwebbed corners of the debate. Center in that web is overdiagnosis (overdetection) with sister ills of false-positives and overtreatments, the harms that trouble – not illegitimately – so many critics of screening mammography, with heated disagreement about both the degree of overdiagnosis, and the validity of different estimation methodologies.

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