Objective: To evaluate digital rectal examination (DRE) as a predictor of prostate cancer (PC) at serum PSA level 3.0-3.9 ng/ml. We compared the PC incidence rates of men with different screening test results in this PSA range and analyzed DRE in comparison with free/total PSA ratio as an additional screening test.
Materials and methods: Using data from the FinRSPC trial, PC incidence rate ratios (IRR) for groups defined by the secondary screening test results (DRE vs. free/total PSA) were calculated for 17-year follow-up, using adjustment for age, family history of PC and place of residence. Screening test performance was evaluated by calculating sensitivity, specificity, positive and negative predictive value, and likelihood ratio.
Results: The IRR for men with a positive DRE compared to those with a negative result was 1.40 (95% confidence interval (CI) 1.00-1.96), while the IRR for men with a positive free/total PSA result compared to those with a negative one was 1.62 (95% CI 1.08-2.43). The estimated sensitivity was 0.15 (95% CI 0.11-0.20, 40/270) for DRE and 0.32 (95% CI 0.23-0.41, 36/113) for free/total PSA, and the specificity 0.91 (95% CI 0.88-0.93, 419/461) for DRE and 0.85 (95% CI 0.78-0.90, 134/158) for free/total PSA.
Conclusions: Our results do not support utility of DRE as a screening test for PC at serum PSA level 3.0-3.9 ng/ml, while the results regarding free/total PSA determination were more encouraging and reconfirm the decision to switch from DRE to free/total PSA.
Keywords: Finland; Prostate neoplasms; epidemiology; incidence; screening.