Evidence of Benefit
Rectal examination is inexpensive, relatively noninvasive, and nonmorbid and can be taught to nonprofessional health workers; however, its effectiveness depends on the skill and experience of the examiner. The possible contribution of routine annual screening by rectal examination in reducing prostate cancer mortality remains to be determined.
Transrectal Ultrasound and Other Imaging Tests
Imaging procedures have been suggested as possible screening modalities for prostate cancer. Prostatic imaging is possible by ultrasound, computed tomography, and magnetic resonance imaging. Each modality has relative merits and disadvantages for distinguishing different features of prostate cancer. Ultrasound has received the most attention, having been examined by several investigators in observational settings. Sensitivity ranged from 71% to 92% for prostatic carcinoma and 60% to 85% for subclinical disease. Specificity values ranged from 49% to 79%, and positive predictive values in the 30% range have been reported. The sensitivity and positive predictive value for ultrasound as a single test may be better than for rectal examination. The rate of cancer is extremely low among ultrasound-positive patients in whom rectal and PSA examinations are normal. TRUS is generally relegated to a role in the diagnostic work-up of an abnormal screening test rather than in the screening algorithm. The cost and poor performance of other imaging modalities have led to their elimination from all early detection algorithms.
Contemporary prostate biopsy relies on spring-loaded biopsy devices that are either digitally guided or guided via ultrasound. TRUS guidance is the most frequently used method of directing prostate needle biopsy because there is some suggestion that the yield of biopsy is improved with such guidance. With the virtually simultaneous clinical acceptance of TRUS, spring-loaded biopsy devices, and the proliferation of PSA screening in the late 1980s, the number of prostate cores obtained from patients with either an abnormal DRE or PSA was most commonly six, using a sextant method of sampling the prostate. There is evidence that the predictable increase in cancer detection rates that would be expected by increasing the number of biopsy cores beyond six does occur; e.g., biopsies with 12 or 15 cores would increase the proportion of biopsied men having cancer detected by 30% to 35%.[25,26] The extent to which such increased detection will reduce morbidity and mortality from the disease or increase the fraction of men treated unnecessarily is unknown.