“Medical researchers are increasingly questioning one of the most widely held beliefs in preventive medicine: that screening healthy people for cancer and catching it early saves lives,” The New York Times reports:

Some, like Pap tests for cervical cancer and tests for colon cancer, show clear benefits. But evidence for others, like mammography and a blood test for early signs of prostate cancer, is less clear, researchers say, and some experts dispute whether their widespread use actually reduces death rates from cancer. And some new tests, like spiral CT scans of the lungs, are being marketed to patients before they have been shown in large, rigorous studies to benefit anyone.

Tests that detect cancer cannot always discern whether the cancer is one that will ultimately kill or is an indolent tumor that might never produce noticeable symptoms.

Even the critics of widespread testing are not necessarily advocating that people forgo it. But they say people should know what the demonstrated benefits are, and the risks, because once people know they have a cancer they usually seek treatment, and the treatments can be debilitating, even life-threatening.

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