COMPARISON OF DIGITAL RECTAL EXAMINATION AND SERUM PROSTATE-SPECIFIC ANTIGEN IN THE EARLY DETECTION OF PROSTATE-CANCER - RESULTS OF A MULTICENTER CLINICAL-TRIAL OF 6,630 MEN

To compare the efficacy of digital rectal examination and serum prosta te specific antigen (PSA) in the early detection of prostate cancer, w e conducted a prospective clinical trial at 6 university centers of 6, 630 male volunteers 50 years old or older who underwent PSA determinat ion (Hybritech Tandom-E or Tandem-R assays) and digital rectal examina tion. Quadrant biopsies were performed if the PSA level was greater th an 4 mu g./l. or digital rectal examination was suspicious, even if tr ansrectal ultrasonography revealed no areas suspicious for cancer. The results showed that 15% of the men had a PSA level of greater than 4 mu g./l., 15% had a suspicious digital rectal examination and 26% had suspicious findings on either or both tests. Of 1,167 biopsies perform ed cancer was detected in 264. PSA detected significantly more tumors (82%, 216 of 264 cancers) than digital rectal examination (55%, 146 of 264, p = 0.001). The cancer detection rate was 3.2% for digital recta l examination, 4.6% for PSA and 5.8% for the 2 methods combined. Posit ive predictive value was 32% for PSA and 21% for digital rectal examin ation. Of 160 patients who underwent radical prostatectomy and patholo gical staging 114 (71%) had organ confined cancer: PSA detected 85 (75 %) and digital rectal examination detected 64 (56%, p = 0.003). Use of the 2 methods in combination increased detection of organ confined di sease by 78% (50 of 64 cases) over digital rectal examination alone. I f the performance of a biopsy would have required suspicious transrect al ultrasonography findings, nearly 40% of the tumors would have been missed. We conclude that the use of PSA in conjunction with digital re ctal examination enhances early prostate cancer detection. Prostatic b iopsy should be considered if either the PSA level is greater than 4 m u g./l. or digital rectal examination is suspicious for cancer, even i n the absence of abnormal transrectal ultrasonography findings.