BIOLOGIC CLASSIFICATION AS AN ALTERNATIVE TO ANATOMIC STAGING FOR CLINICALLY LOCALIZED PROSTATE-CANCER - A PROPOSAL BASED ON PATIENTS TREATED WITH EXTERNAL-BEAM RADIOTHERAPY

Objectives. The prognostic significance of clinical stage in patients with prostate cancer who are treated with external beam radiotherapy i s unclear. This study evaluates multiple pretreatment factors, includi ng clinical stage, to determine which are the best prognostic factors, and develops a classification system based on these factors. Methods. All 249 evaluable patients with clinically localized adenocarcinoma o f the prostate treated with definitive conformal external beam radioth erapy without androgen deprivation at our institution between 1989 and 1995 were analyzed. Clinical stage, serum PSA level, Gleason score, r ace, and history of transurethral resection of the prostate (TURP) wer e evaluated for their ability to predict biochemical disease-free surv ival (BDFS). Factors predictive of BDFS were then used to construct a classification system. The classification system was then analyzed for its ability to predict BDFS, distant metastases, local recurrence, an d clinical disease free survival in univariate and multivariate analys es. Median follow-up was 27 months. Results. Gleason score and PSA pre dicted BDFS in multivariate analysis (both P < 0.0001), whereas clinic al stage, race, and history of a TURF did not. These two biologic fact ors were combined into a four-level classification system. This classi fication system was analyzed together with Gleason score and PSA and w as found to be the only predictor of BDFS on multivariate analysis (P < 0.0001). In addition, this classification system was the only predic tor of distant metastases in multivariate analysis (P (0.0001). Conclu sions. The classification system derived herein based on the biologic factors of Gleason score and serum PSA levels is the sole predictor of distant metastases and biochemical recurrence for patients treated wi th definitive conformal external beam radiotherapy for clinically loca lized prostate cancer. This classification system may be useful when c omparing competing therapies and stratifying patients in clinical tria ls, but requires validation from other institutions and other therapie s prior to its widespread use. (C) 1998, Elsevier Science Inc. All rig hts reserved.