The idea that getting a battery of medical tests to rule out all types of cancer is not only ineffective but can cause harm.

Certainly, the rationale behind screening seems obvious. The earlier cancers are diagnosed, the more often lives will be saved, right? With enough screening, we might even stop cancer.

If only. Finding cancer early isn’t enough. To reduce cancer deaths, treatment must work, yet it doesn’t always. Second, it must work better when started earlier. But for some cancers, later treatment works as well. (That’s why there is no big push for testicular cancer screening — it is usually curable at any stage.)

And some of the worst cancers aren’t detected by screening. They appear suddenly, between regular screenings, and are difficult to treat because they are so aggressive.

Biopsy, exploratory surgery , radiation and chemotherapy as the result of positive or abnormal results from screening, pose dangers and have side affects of their own to be seriously considered.