Relative contribution of digital rectal examination and transrectal ultrasonography in interpreting serum prostate-specific antigen values for screening prostate cancer in Arab men

Abstract

Background: This study was conducted to determine the utility of digital rectal examination (DRE), transrectal ultrasonography (TRUS) and serum prostate-specific antigen (PSA) in the diagnosis of prostate cancer in men in Arabia, an are of the world with a relatively low incidence of this disease. Patients and methods: 329 patients suspected of having prostate cancer on account of raised serum PSA level (> 4 ng/ml), DRE or TRUS findings, underwent TRUS-guided prostate biopsy. Raised PSA individually as well as combined, or a lesion suspicious of carcinoma on DRE or TRUS was recorded as PSA (+), DRE (+) or TRUS (+), respectively. The contribution of DRE, TRUS and serum PSA to the diagnosis of prostate cancer was analysed. Results: Of the 329 patients who had prostate biopsies 109 cases (33.1%) had PCa. Of these 109 patients 56 (51 %) had DRE (+), 77 (42%) had TRUS (+) and 49 (66%) had both DRE (+) and TRUS (+). Statistical analysis revealed that DRE (+) tripled the probability for cancer. PSA over a range of 10-50 ng/mL demonstrated an increasing cancer probability ranging from 2 to 3 fold. TRUS (+) was only significantly associated with cancer risk if PSA was elevated. The presence of all three factors increased the cancer probability by 6 to 7 fold. Conclusion: TRUS findings are dependent on PSA for interpretation while DRE (+) with elevated PSA makes PCa more likely.