Overdiagnosing Cancer: When is Enough Enough?
Our medical system is designed to diagnose and treat. If a patient, for instance, comes in and wants to be screened for cancer, regardless of the situation, a doctor will do the screening. If the result is positive, the team will take action. This is just how the system works. There are far too many parties involved not to, including pharmacies, drug manufacturers, insurance providers, and medical centers. To not take action means a lot of people won’t get paid. However, could one argue that there is an epidemic of overdiagnosis? When is enough enough?
Wikipedia defines the term “overdiagnosis” as “ the diagnosis of ‘disease’ that will never cause symptoms or death during a patient’s ordinarily expected lifetime. Overdiagnosis is a side effect of screening for early forms of disease.
Author Louise Davies of Dartmouth and her co-authors of the Annals define overdiagnosis of cancer, specifically, as the “detection of a histologically confirmed cancer through screening that would not otherwise have been diagnosed in a person’s lifetime had screening not been done.” In other words, if a 105-year-old man asked to be screened and cancer was diagnosed, this may be considered “overdiagnosis” since he is already living beyond his life expectancy.
Davies and her colleagues argue that the concept of overdiagnosis is confusing and it “is often conflated with related harms (such as overtreatment, misclassification, false-positive results, and overdetection) and is difficult to measure because it cannot be directly observed.” Yet, because “the U.S. Preventive Services Task Force (USPSTF) issues screening recommendations aimed largely at healthy persons, it has a particular interest in understanding harms related to screening, especially but not limited to overdiagnosis.” Thus, there is an interest in nailing down the proper terminology surrounding overdiagnosis and figuring out what constitutes this and what does not. There is simply not enough solid proof of when overdiagnosing is occurring.
In considering whether cancer would have been caught and treated without being termed an “overdiagnosis,” the Davies and fellow authors use existing data regarding the type of cancer, the age of the patient, and comorbidities of patients to make a best guess at how long they would have lived without catching the cancer. Diagnosing the 105-year-old man may be considered overdiagnosing, because he will likely not live long enough to benefit from treatment, but not an otherwise healthy 30-year-old man who may benefit from a better quality of life if the cancer is treated effectively.
Professor Gilbert Welch, from the Dartmouth Institute for Health Policy and Clinical Practice in the U.S., explained, “The easiest evidence to understand is when incidence shoots up following early diagnosis and mortality stays the same.”
Professor Peter Sasieni, Cancer Research UK’s expert in cancer screening and epidemiology from King’s College London added, “For every woman who is prevented from dying from breast cancer, three others will be diagnosed that wouldn’t have otherwise if they didn’t participate in breast screening. Those three will be treated and will probably have surgery, radiotherapy and possibly hormonal therapy. I think the language we use to talk about cancer is a big problem in society. I think most people still think of a cancer diagnosis as a death sentence. The Holy Grail is finding something that tells us which cancers are harmless and which aren’t, and then we can distinguish between them and ignore the harmless ones.”