This article summarizes the phenomenon of cancer overdiagnosis—the diagnosis of a “cancer” that would otherwise not go on to cause symptoms or death. We describe the two prerequisites for cancer overdiagnosis to occur: the existence of a silent disease reservoir and activities leading to its detection (particularly cancer screening).
We estimated the magnitude of overdiagnosis from randomized trials: about 25% of mammographically detected breast cancers, 50% of chest x-ray and/or sputum-detected lung cancers, and 60% of prostate-specific antigen–detected prostate cancers.
We also review data from observational studies and population-based cancer statistics suggesting overdiagnosis in computed tomography–detected lung cancer, neuroblastoma, thyroid cancer, melanoma, and kidney cancer. To address the problem, patients must be adequately informed of the nature and the magnitude of the trade-off involved with early cancer detection. Equally important, researchers need to work to develop better estimates of the magnitude of overdiagnosis, and develop clinical strategies to help minimize it.
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Why cancer screening has never been shown to “save lives”—and what we can do about it Despite growing appreciation of the harms of cancer screening,1 2 3 advocates still claim that it “saves lives.”4 This assertion rests, however, on reductions in disease specific mortality rather than overall mortality.
Cancer screening – does it save lives? The claim that cancer screening saves lives is based on fewer deaths due to the target cancer. Vinay Prasad, assistant professor at Oregon Health and Science University, joins us to argue that reductions in overall mortality should be the benchmark and call for higher standards of evidence for cancer screening.
(Source: bmj.com; October 29, 2015; https://tinyurl.com/y3qnm8oe)
As I have watched my wife struggle with Hashimoto’s disease and other health issues, it is in these challenges where new understanding of the protocols and new understanding of the body came to be. An understanding that helped me realize if she could get well, who else is out there like my wife that is struggling?— Dr. Jay Davidson, DC, DPSc