Radiotherapy for node-positive prostate cancer correlates with improved survival

Abstract

Purpose or Objective Node positive prostate cancer (N+PCa) represents a heterogeneous cohort of patients, and the management strategy for these men remains controversial. Patients with N+PCa are often grouped into either locally advanced or metastatic PCa with little supporting evidence for either approach. We aimed to evaluate patterns of care and outcomes across four UK centres and analyse prognostic variables and treatment parameters for impact on clinical outcomes. Materials and Methods Data on men with clinically diagnosed N+PCa treated between 2011 and 2019 were collected retrospectively. All of them had baseline CT scan to confirm the presence of pelvic nodes. Baseline prognostic variables included: age, performance status (PS) prostate-specific antigen (PSA), Gleason score, tumour stage (T2/T3 vs T4) and nodal disease burden. Data on therapeutic options collected included: androgen deprivation therapy (ADT), radiotherapy (RT), surgery and chemotherapy. Outcome parameters collected included overall survival (= time from the date of diagnosis to death due to any cause), bPFS (biochemical PSA progression free survival) (biochemical progression = PSA nadir + 2) and rPFS (radiological progression-free survival). Descriptive statistics were performed, and survival was estimated using the Kaplan-Meier method. A Cox-proportional hazards model was used for multivariate analysis. Results Data on 337 men with a median follow-up time of 48 months (45-51) were collected. 96% of men were treated with ADT, with 20% receiving ADT alone. 32% of men received lifelong ADT and 64% had ADT for 2-3 years. 70% of men had RT, with 38% receiving RT to the prostate and pelvic nodes. 22% of men had docetaxel chemotherapy with 16% receiving docetaxel chemotherapy in addition to prostate RT. The median OS, bPFS and rPFS for the whole group were 9.3 (95% CI: 8.8-NR), 8.4 (95% CI: 8.3-NR) and 8.5 years (95% CI: 8.4-NR) respectively. The effect of prostate RT (± pelvic nodal RT) was analyzed within a multivariable analysis model, adjusting for age, PSA, Gleason score, T stage, PS and ADT, RT improved OS [HR = 0.39 (0.17-0.90) p= 0.028], bPFS [HR=0.27 (0.13-0.53) p <0.001] and rPFS [HR=0.23 (0.10-0.50)) p = 0.001] (figure 2). Gleason grade group 5 was found to be an independent prognostic factor for OS [HR=2.09 (1.33-3.29) p=0.001] after adjusting for other variables. No other tumour or treatment factors were found to be significant. Conclusion This is the first large retrospective study to report patient-level analysis of N+PCa prostate cancer. We have shown that definitive treatment with ADT and prostate RT is associated with improved survival. Our follow-on work aims to build a prognostic model and validate our findings with an independent data set