False positives show need to adjust expectations for cancer screening tests

Several years ago, during an annual mammogram, my wife, who is in her 40s, was told a mass had been found in one of her breasts. Anxious and uncertain, she had a biopsy, and we braced for the worst.

Several years ago, during an annual mammogram, my wife, who is in her 40s, was told a mass had been found in one of her breasts. Anxious and uncertain, she had a biopsy, and we braced for the worst.

My father-in-law, when in his 50s, went through a similarly harrowing experience when a prostate specific antigen (PSA) test given during a routine physical exam came out positive, and he underwent a prostate biopsy.

Fortunately, both my wife and father-in-law were found to be victims not of cancer but of false positives. It’s a common outcome — about three of every 10 mammograms and about seven of every 10 positive PSA tests result in false alarms. Like my wife and father-in-law, many people may feel that the short-term pain of these tests is worth the reassurance that they are cancer-free. But lately the idea that screening tests are a surefire weapon against cancer has been undermined.

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