Predicting the long-term risk of prostate cancer-specific mortality after radical prostatectomy

Abstract

5007 Background: Nomograms that predict prostate-specific antigen (PSA) defined biochemical recurrence (BCR) of prostate cancer after radical prostatectomy are the most widely used prediction tools in oncology for treatment decision making and counseling. While BCR universally antedates prostate cancer-specific mortality (PCSM), it is a limited surrogate endpoint due to its variable natural history. Nomograms that accurately predict the risk of PCSM are needed. Methods: Using Fine and Gray competing risk regression analysis, the clinical data and follow-up information of 11,521 patients treated with radical prostatectomy at four academic centers from 1987 to 2005 were modeled to predict PCSM. The model was externally validated on 12,893 patients treated at a separate institution during the same period. Results: The 15-year PCSM and all-cause mortality was 7% and 33%, respectively. The 15-year PCSM for patients with final pathological Gleason score 2–6, 3+4, 4+3, and 8–10 was 1%, 7%, 8%, and 49%, respectively. By pathologic stage, the risks were 2%, 7%, 29%, and 23% for organ-confined, extraprostatic extension, seminal vesicle invasion, and lymph node-positive prostate cancer. Of 3756 patients with organ-confined and Gleason 2–6 cancer, only 1 (0.03%) died from prostate cancer. Primary and secondary Gleason grade (p < 0.001 for both), seminal vesicle invasion (p < 0.001), and year of surgery (p = 0.002) were significant predictors of PCSM. A nomogram predicting 15-year PCSM based on pathologic parameters was accurate and discriminating with an externally-validated concordance index of 0.92. Conclusions: A nomogram has been constructed that predicts the long-term risk of PCSM after radical prostatectomy based on the pathologic grade and stage of the cancer. The presence of poorly differentiated cancer and seminal vesicle invasion are the prime determinants of PCSM. Our study suggests that biomarkers may have limited empiric prognostic utility as PCSM can be accurately predicted once the pathologic features of prostate cancer are known. No significant financial relationships to disclose.