November 6, 2014 | H. Gilbert Welch writes in the New York Times opinion pages about a peculiar consequence of a concerted push for early cancer detection in South Korea, where diagnoses of thyroid cancer have risen fifteen-fold since the 1990's. Most of the newly discovered cases are non-symptomatic and unlikely to ever become life-threatening, but preemptive treatment carries risks that can have a serious effect on the medical system. In the United States, routine screening for breast and prostate cancer may have similar under-appreciated costs. New York Times