Development of a Novel Nomogram to Predict Biochemical Failure and Prostate Cancer-Specific Mortality After Definitive Radiotherapy in Patients with Gleason Score 7 Prostate Cancer.

Abstract

Background: Gleason score (GS) 7 prostate cancer (PCa) encompasses biologically heterogeneous subgroups with differing prognoses. This study aimed to assess long-term oncologic outcomes and develop a predictive nomogram for patients with GS 7 PCa treated with definitive radiotherapy (RT) with or without androgen deprivation therapy (ADT).

Methods: We retrospectively analysed the data of 372 patients with GS 7 PCa treated with RT between 2010 and 2020. Kaplan- Meier analysis was used to estimate freedom from biochemical failure (FFBF) and prostate cancer-specific survival (PCSS). Prognostic factors were identified using Cox regression models. A nomogram was constructed to predict individualised risks of FFBF and PCSS. Model performance was evaluated using time-dependent area under the curve (AUC), calibration plots and decision curve analysis.

Results: At a median follow-up of 102.6 months, the 8-year FFBF and PCSS rates were 88.2% and 96.3%, respectively. Patients with GS 4+3 had significantly poorer outcomes than those with GS 3+4 (FFBF: 84.3% vs. 91.1%, p = 0.010; PCSS: 92.1% vs. 98.5%, p = 0.002). Multivariable analysis revealed that young age (hazard ratio (HR): 0.95, p = 0.002), prostate specific antigen (PSA) >10 ng/mL (HR: 2.95, p = 0.010), GS 4+3 (HR: 2.67, p = 0.002) and absence of ADT (HR: 5.77, p < 0.001) were independently associated with an increased risk of biochemical failure. The final nomogram incorporating age, PSA, GS pattern, T stage, risk group, RT field, simultaneous integrated boost (SIB) use and ADT status showed excellent predictive performance, with 8-year time-dependent AUCs of 0.773 for FFBF and 0.914 for PCSS. Threshold scores > 0.5 for FFBF and > 1.06 for PCSS were associated with an increased event risk.

Conclusions: GS 4+3 emerged as the strongest predictor of poor outcomes, alongside elevated PSA, absence of ADT and young age. The proposed nomogram provides accurate individualised risk stratification and may assist in tailoring treatment intensity and follow-up in patients with GS 7 PCa undergoing definitive RT. External validation is warranted.