By Theo Schall



If you had cancer that wasn’t going to kill you or even make you sick, would you want to know? If you found out you had cancer, would you want treatment, even if it might be worse than the disease itself?


I wrote last month about a company called Miroculus, a tech start-up trying to build a simple device that can quickly screen for hundreds of cancers using just a small blood sample. The company’s sleek website extorts readers to “imagine a simple blood test that can tell you, at the molecular level, the exact type of disease you have and its severity before presenting any symptoms.” In thinking about Miriam, the company’s device, I questioned the benefit of improving access to diagnosis without considering the implications for treatment. I wondered how regular, minimally invasive monitoring might change our definitions of disease. And I pointed out that Americans already overtest and overtreat, to our detriment.


A new report on the potential harms of early cancer detection illustrates what’s at stake. A few weeks ago, a perspective in the New England Journal of Medicine reported that after the roll-out of a low-cost national cancer screening program, South Korea’s rate of thyroid cancer diagnoses grew rapidly. “In 2011,” the researchers wrote, “the rate of thyroid-cancer diagnoses was 15 times that observed in 1993.” Yet while 400,000 South Koreans were diagnosed with thyroid cancer in 2011, the number of people dying of the disease stayed where it’s been for the past decade – around 300 to 400 a year. The problem wasn’t that exponentially more people got sick, but that more people were labelled “sick.”


Being diagnosed with a disease comes with its own risks. South Koreans diagnosed with thyroid cancer underwent surgery and many now will require lifelong thyroid-replacement therapy. In the large sample of patients the researchers examined, 2% developed vocal-chord paralysis. These are not insignificant harms. As the NEJM researchers pointed out, subclinical thyroid disease is common and rarely fatal. The risk of being screened and then treated for thyroid cancer is likely to exceed the risk of the cancer itself, at least when you’re testing entire populations. While not every cancer works like thyroid cancer – some should be caught and treated as soon as possible – it’s not the only one that can remain dormant in the body for long periods without requiring treatment.


This brings us back to Miroculus and the larger cohort of tech companies whose aim is to integrate regular, comprehensive disease into our daily lives. Being diagnosed with cancer is traumatic for patients and families. Part of the burden is what’s called the “diagnostic odyssey,” the often circuitous journey through the medical system’s evaluations, referrals, and tests just to find the correct diagnosis. The desire to cut through the inefficiency and give patients a clear diagnosis early, when their prognosis might be better, is certainly laudable. The founders of these tech companies want to do good for very sick people.


Yet diagnosis itself is also burdensome. Learning you have cancer is difficult to cope with. Patients often have trouble understanding cancer diagnoses, prognoses, and treatments. And as the South Korean example makes clear, our desire to do something to fight disease may not make us any healthier. Sometimes it’s better not to know you have a disease because it isn’t going to make you sick. Screening people for 200 cancers at a time, as Miroculus hopes to do in the near future, has the potential to do those people a lot of harm. Whether that harm is offset by the benefits of early detection is something we’ll have to carefully watch as more, and more rigorous, routine screening becomes the norm.

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Theo Schall

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