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.
The PSA test has been examined in several observational settings for initial diagnosis of disease, as a tool to monitor for recurrence after initial therapy, and for prognosis of outcomes after therapy. There is no PSA value below which a man can be assured that he has no risk of prostate cancer. Parameter estimates for this test include sensitivity in the range of 70%.
In a review of the Prostate Cancer Prevention Trial, 2,950 men who never had a PSA level higher than 4.0 ng/mL or an abnormal DRE had a final PSA determination and underwent a prostate biopsy after being in the study for 7 years. There was a 15.2% (n = 449) biopsy-proven prevalence of prostate cancer in men with PSA levels no higher than 4.0 ng/mL. High-grade prostate cancer (defined as Gleason score ≥7) was seen in 15.8% (n = 71) of these men. Size of the tumor was not reported.
In the placebo arm of the Prostate Cancer Prevention Trial, there was no cutpoint of PSA with simultaneous high sensitivity and high specificity for detection of prostate cancer in healthy men, but rather a continuum of prostate cancer risk at all values of PSA.
The potential value of the test appears to be in its simplicity, objectivity, reproducibility, relative lack of invasiveness, and relatively low cost. PSA has increased the detection rate of early-stage cancers, some of which may be curable by local-modality therapies, but others of which do not require treatment.[30,31,32,33] Circumstantial evidence favoring screening for prostate cancer is analogous to that for lung cancer screening in the 1950s and 1960s; screening results in a shift to a higher proportion of cases with earlier-stage cancers at diagnosis. This shift may result in mortality reduction. For lung cancer, no mortality benefit resulted. However, the possibility of identifying an excessive number of false-positives in the form of benign prostatic lesions requires that the test be evaluated carefully. Furthermore, there is a risk of overdiagnosis and overtreatment, i.e., the detection of a histological malignancy that if left untreated would have had a benign or indolent natural history and would have been of no clinical significance.