Effect of Preoperative Risk Group Stratification on Oncologic Outcomes of Patients with Adverse Pathologic Findings at Radical Prostatectomy

BACKGROUND: Current National Comprehensive Cancer Network guidelines recommend postoperative radiation therapy based only on adverse pathologic findings (APFs), irrespective of preoperative risk group. We assessed whether a model incorporating both the preoperative risk group and APFs could predict long-term oncologic outcomes better than a model based on APFs alone. METHODS: We retrospectively reviewed 4,404 men who underwent radical prostatectomy (RP) at our institution between 1992 and 2014. After excluding patients receiving neoadjuvant therapy or with incomplete pathological or follow-up data, 3,092 men were included in the final analysis. APFs were defined as extraprostatic extension (EPE), seminal vesicle invasion (SVI), or a positive surgical margin (PSM). The adequacy of model fit to the data was compared using the likelihood-ratio test between the models with and without risk groups, and model discrimination was compared with the concordance index (c-index) for predicting biochemical recurrence (BCR) and prostate cancer-specific mortality (PCSM). We performed multivariate Cox proportional hazard model and competing risk regression analyses to identify predictors of BCR and PCSM in the total patient group and each of the risk groups. RESULTS: Adding risk groups to the model containing only APFs significantly improved the fit to the data (likelihood-ratio test, p <0.001) and the c-index increased from 0.693 to 0.732 for BCR and from 0.707 to 0.747 for PCSM. A RP Gleason score (GS) ≥8 and a PSM were independently associated with BCR in the total patient group and also each risk group. However, only a GS ≥8 and SVI were associated with PCSM in the total patient group (GS ≥8: hazard ratio [HR] 5.39 and SVI: HR 3.36) and the high-risk group (GS ≥8: HR 6.31 and SVI: HR 4.05). CONCLUSION: The postoperative estimation of oncologic outcomes in men with APFs at RP was improved by considering preoperative risk group stratification. Although a PSM was an independent predictor for BCR, only a RP GS ≥8 and SVI were associated with PCSM in the total patient and high-risk groups.