Roach's mathematical equations in predicting pathological stage in men with clinically localized prostate cancer

The therapeutic choice in patients with clinically localized prostate cancer depends on preoperative clinical stage. Diagnostic instruments currently available for such an evaluation--considered separately--have not shown enough efficacy. Roach has recently introduced three simple mathematical equations that--on the basis of prostate-specific antigen and the biopsy Gleason score--are aimed at calculating the definitive pathological stage. We retrospectively analyzed our radical prostatectomy data base to assess the accuracy of the equations in predicting the final stage in patients with clinically localized prostate cancer. METHODS STUDY DESIGN: The study included 173 patients who had undergone radical retropubic prostatectomy at our Institution. Patients were divided into 25 groups, depending on preoperative PSA and the biopsy Gleason score. The risk of extracapsular neoplastic growth, seminal vesicle involvement and lymph node involvement was calculated for each group by means of Roach's equations. On the basis of definitive histological examinations, we compared the expected risk to the observed risk.

The observed risk fell within the interval of expected risk in 16 of 17 groups (94%) regarding the evaluation of extracapsular growth, in 15 of 17 (88%) regarding the analysis of seminal vesicle involvement, and in 14 of 17 (82%) regarding the evaluation of lymph node involvement. Therefore, the observed event was in agreement with the expected event in 45 of 51 groups (88%).

The equations represent a practical and effective instrument for preoperative clinical staging in patients with localized prostate cancer. By means of these mathematical formulas, one can assess the correct prognosis and--above all--plan the best therapeutic approach.