Predictors for biopsy outcome in the European Randomized Study of Screening for Prostate Cancer (Rotterdam region).

Background: In the European Randomized Study of Screening for Prostate Cancer (ERSPC, Rotterdam region), men aged 55-74 years are screened for prostate cancer by prostate-specific antigen (PSA) sampling, digital rectal examination (DRE), and transrectal ultrasound investigation (TRUS). All men with a PSA > or =4 ng/ml and/or a suspicious DRE and/or a suspicious TRUS are biopsied.

Methods: Logistic regression analysis was applied to derive a predictive index that equals the chance to find prostate cancer in a biopsy given the outcomes of the screening tests. This model was used to assess the number of cancers that could have been detected if all men had been biopsied (extrapolation). Furthermore, the model was used to study the possibilities for improvement of the current screening protocol.

Results: PSA was the dominant predictor for prostate cancer in a biopsy, followed by prostate volume, DRE, and TRUS result. It is assessed that 69% (95% CI, 52-86%) of cancers that could be identified if all men were biopsied are currently detected. Application of the same methods to screening data obtained in Göteborg (the Swedish ERSPC partner) yielded almost identical results. It was found that, in the Rotterdam protocol, a considerable number of men were biopsied according to the screening protocol with an assessed lower chance to have prostate cancer than men who were not biopsied according to the protocol.

Conclusions: The chance to detect prostate cancer in a biopsy can be modeled quite accurately as a function of serum PSA, prostate volume, DRE, and TRUS results. Important improvements in the screening protocol can be achieved by the application of the predictive index.