Overdiagnosis was not a term I ever heard in medical school, and I suspect it is one that few or you had heard of much more than a year or two ago. Overdiagnosis is when a condition is diagnosed that is not causing any symptoms for a patient now, nor will it cause symptoms at a later time in their life. I wrote about overdiagnosis earlier after reading the excellent book, “Overdiagnosed: Making People Sick in the Pursuit of Health” by H Gilbert Welch.
This book nicely discusses the issues of overdiagnosis in both chronic disease and in cancers. The long-held assumption that all malignancies left untreated progress, spread and lead to death is simply not true. We are learning that many types of cancer have unpredictable courses. Prostate cancer is the most notorious of these, with good evidence showing that most prostate cancers are ones patients live with asymptomatically whether they know about them or not and die of something else without ever having symptoms of the prostate cancer. This is the primary issue behind the recent USPSTF “D” recommendation against routine PSA screening in asymptomatic men. There is strong evidence that some percentage of renal cell cancers, some types of breast cancer and thyroid cancers not infrequently regress or remain indolent and never lead to symptoms.
The recent evidence suggesting frequent overdiagnosis in breast cancer is very disturbing. An April 3 article in the Annals of Internal Medicine in a large retrospective review in Norway infers a 15-25% incidence of overdiagnosis in women found to have breast cancer on mammographic screening. They used every other year screening, and suggest that for every 2500 women screened 6-10 cases of overdiagnosis occurred, 20 women were diagnosed with breast cancer that was not overdiagnosis, and 1 death related to breast cancer was prevented. We have strongly encouraged women to get annual mammograms for years. Personal anecdotal experience can make us even more confident that we are doing the right thing. I have had many patients diagnosed with early breast cancer by mammogram over the last 20+ years, and until recently had not had any women over age 40 that I can recall diagnosed with advanced stage breast cancer who had been getting their annual mammograms. It was very intuitive and tempting for me to believe that I was saving many lives and preventing much morbidity by aggressively pursuing early breast cancer diagnosis. I know that I have put many women through emotionally stressful and uncomfortable additional testing, biopsies, and breast cancer treatment. It is concerning to think that I may be subjecting some of these women to overdiagnosis and unnecessary treatment, but until we as a society actively address the issue of overdiagnosis and try to find ways to figure out which early cancers found on screening can be managed with active surveillance and which need curative treatment we are left with the inevitable overdiagnosis dilemma. This will involve asking a cohort of women with various very early cancers to be observed for progression prior to intervention. Whether this is going to be acceptable is not clear. We need to do the same thing for men with early prostate cancer. We are following lots of men with prostate cancer, but as far as I know not in a formal study that will give us help in knowing which cancers can be safely followed. For now I’m doing nothing different except keeping my eyes wide open to further research and recommendations.
Much of what we do in medicine today is aimed at early diagnosis of asymptomatic disease, and overdiagnosis is a very valid concern any time we are screening for asymptomatic disease. The recent changes in criterion for hypertension, diabetes and hypercholesterolemia are leading us to the preventative treatment of many diseases that are of themselves asymptomatic. The whole issue of overdiagnosis is going to be fascinating to follow over the next decade or two.
You may also enjoy: PSA Controversy Continues