We all know about the medical screening tests that are widely recommended. The annual (or biannual) Pap smear for women, baseline mammogram between 35 and 40 and regularly every couple years thereafter, the annual prostate check for men over 40, cholesterol screening, colonoscopy after 50, etc. We also hear a lot about how serious diseases like cancer are so much more treatable when they're caught early, so there's temptation to screen more broadly. We even witnessed the trend of full-body scanning that people paid for out-of-pocket (often identifying mysterious spots in the body that were causing no trouble but now required a full work-up to diagnose).
The standard assortment of broadly recommended tests have been shown by the preponderance of research to produce more good than harm. You do run the risk of a false-positive test creating unnecessary worry and resulting in unnecessary follow-up procedures, but on balance, widespread use of the standard tests is believed to benefit the population.
With Peter Jennings' recent death and Dana Reeve's diagnosis of lung cancer, the worried well may be tempted to ask their physicians for a screening CT scan. In today's NYT, a group of Dartmouth researchers explain why this is a bad idea at present. It's a too little involved to excerpt it here, so go read the op-ed if you're interested in grasping the connotations of unnecessary early screening.