Seniors love their doctors, it is frequently noted. And their doctors may love them just as much–older patients tend not to question medical recommendations. But senior patients ought to question the tendency to prescribe tests that are unnecessary, uncomfortable, anxiety-producing and possibly even harmful, studies show.

Skepticism is growing over the widespread practice of screening patients in their 70s, 80s and even 90s for cancers and other slow-growing diseases that are unlikely to affect their health. For example, routine screening for prostate cancer in a senior patient may be pointless because even if it were detected, the patient would be far more likely to die of old age than a slow-growing cancer.

Too often unnecessary test trigger invasive treatments for slow-growing diseases, which, rather than improving or extending life, reduce its quality in the final months. Dartmouth physician Lisa M. Schwartz, who has coauthored a new book entitled “Overdiagnosed: Making People Sick in the Pursuit of Health,” cites one such case: a healthy 78-year-old man who was left incontinent and impotent by radiation treatments for a prostate cancer that was not likely to kill him.

Despite the fact that the independent U.S. Preventive Services Task Force, which evaluates the risks and benefits of screening tests, does not endorse prostate or colon cancer screening after the age of 75, many seniors continue to undergo these tests. The panel also does not endorse mammography after age 74 or Pap smears after 65.

A Texas study appearing in the Archives of Internal Medicine found that 46 percent of Medicare beneficiaries who had had a previous normal colonoscopy underwent a repeat of the test less than seven years and sometimes as few as three years later. The task force, however, recommends a follow-up test 10 years after a normal one. One-quarter of those tests was performed for no discernible reason.

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