Detecting prostate cancer at an early stage is difficult. One method is the digital rectal exam, or DRE. A physician inserts a gloved index finger into the rectum and feels the lower part of the prostate for abnormal growths or firm or hard areas. This is not a high-tech procedure involving laboratory tests and equipment, nor is it especially painful for patients, though most men find the probing uncomfortable and some try to avoid it.
The drawback to this test is its unreliability. Two thirds of all suspicious DRE findings that lead to a biopsy turn out to be noncancerous, while many prostate cancers go unnoticed.
Another diagnostic tool is called TRUS, for transrectal ultrasound. But detection by this method is even less accurate than by DRE, because the ultrasonic appearance of cancer in the prostate is very similar to that of benign inflammation. Ultrasound is also more time-consuming and costly than either a DRE or the prostate-specific antigen (PSA) test described below and so is usually used after the other two screening methods reveal abnormalities.
The PSA test was introduced in 1986 as a means of monitoring the progress of cancer in men who had been diagnosed with the disease. But urologists and other physicians began using it to screen men who appeared to be healthy, and during the past 20 years the test has come into wide use, especially for men over 50.
The problem is that PSA testing is not very good at saving lives. Of the two best, largest trials—both published in the New England Journal of Medicine in 2009—one found that screening had no effect on mortality, and the other found little effect. Both studies, however, found definite harms from screening (see below). That’s why the U.S. Preventive Services Task Force (a panel of experts who periodically evaluate available scientific evidence for screening tests and issue recommendations based on their evaluations) now recommends against routine PSA testing for healthy men, although you and your doctor still may decide to proceed with screening after careful discussion