Up to 80% of abnormalities discovered through full-body scans are not fatal — name anything, it can be found in someone who appears otherwise to be healthy. But these small abnormalities cause doctors to make diagnoses based on a slight oddity on a screen rather than on actual symptoms.
So why do we obsessively subject ourselves to such screenings when we are otherwise healthy? We screen everything from lungs to kidneys, all to catch a disease before it makes us sick. But we don’t realize that in the cases where abnormalities are found, the majority of people will live the entirety of their lives without being affected by them at all. Prescribing medication or medical procedures to deal with them can actually cause more harm than good.
There is a term for how treatment, either medicinal or procedural, for an asymptomatic disease can actually harm the patient: overdiagnosis.
Take the thyroid, for example. Thyroid nodules are notorious for being incredibly common — estimates of nodule incidence (as detected from an ultrasound) range from 20-65% of the population, yet almost all are entirely asymptomatic. What really matters, however, is not whether you have a nodule, but the size of the nodule, roughly measured through palpability. And even then, while 4-7% of the population has these palpable nodules, thyroid cancer occurs in only 5-10% of those cases. Out of a thousand, two to seven people will have thyroid cancer.
Sure, seven still sounds like a lot, but not when you compare it to the number of people with thyroid nodules: 200-650. Those that are risk-averse would argue that doctors should treat everyone to avoid missing those two to seven cases of actual cancer, but that treatment would most likely involve removal of the thyroid and a lifetime of hormone replacement pills for a lot of otherwise healthy people. Of course, doctors and patients tend to want to err on the safe side, and we have yet to perfect the ability to detect the actual cancer, the result being that thyroid cancer is overdiagnosed.
Why do doctors have a tendency to overdiagnose? As previously alluded to, they don’t want to brush something off as nothing and have that come back in the form of a malpractice suit. They are afraid of the outlier, afraid of the zebra.
I’m not writing as a doctor — though many doctors have written on this subject — but I am writing as a patient. And of course, I’m not telling you to stop going to the doctor; there are definitely cases where catching a disease before symptoms have developed does prevent it from causing real harm (brain cancer is the obvious example). However, if we are all aware of the tendency to overtreat, we can approach the situation more knowledgeably and have productive discussions about the benefits and risks of treatment options with our doctors. The first step is for all of us, both patients and doctors, to realize that just as we are not perfect, neither are our bodies.
Margaret Hansen is a rising senior in the College. Disorderly Conduct appears every other Friday.
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