Objectives: To determine whether an additional subclassification of the assessed clinical stage for prostate cancer before biopsy increases our ability to predict the biopsy outcome. A suspicious digital rectal examination (DRE) and/or a suspicious transrectal ultrasound (TRUS) investigation increases the likelihood of prostate cancer given a certain prostate-specific antigen level.
Methods: Biopsies done in 2199 men with suspicious DRE and/or TRUS findings were studied. The clinical stage was assessed according to the 1992 TNM classification. Univariate and multivariate statistical analyses were performed.
Results: The assessed extent of disease classified as intracapsular or extracapsular (ie, clinical Stage T2 versus T3 and T4) was a significant independent predictor for the biopsy outcome. Men with suspected extracapsular disease on the basis of the DRE findings before the sextant biopsy had a twofold increased odds ratio of having prostate cancer detected compared with men with suspected intracapsular disease. A suspicion of extracapsular disease on the basis of TRUS findings, however, significantly decreased the risk of having prostate cancer detected in a biopsy.
Conclusions: We found a modified version of the clinical stage (ie, extracapsular, clinical T3 or T4 cancer versus intracapsular) to be significantly better in predicting the presence of prostate cancer at a given prostate-specific antigen level than a simple "yes or no abnormality found on DRE and/or TRUS" qualification. A suspicion of extracapsular disease raised on the basis of the DRE findings should be valued differently than a similar suspicion raised on the basis of the TRUS findings. Apparently, the extracapsular lesions seen by TRUS are primarily nonmalignant.