The Impact of Radiotherapy on the Primary Tumor in Patients with Metastatic High-Volume Castration-Sensitive Prostate...

Background: Retrospective studies suggest that local radiotherapy on the prostate improves overall survival in the metastatic setting, but its benefit in patients with high-burden metastatic disease is still uncertain. Methods: We conducted a retrospective study of 100 high-metastatic-burden prostate cancer patients at Hadassah Ein Karem Medical Center from 2004 to 2021. Patients receiving local RT alongside standard treatment were compared to those receiving standard treatment alone. Prostate RT involved EBRT to the prostate/seminal vesicles with/without pelvic lymph nodes, delivering 54-60 Gy in up to 3 Gy fractions. The standard treatment used was ADT including or excluding chemotherapy. Subsequently, we performed 1:1 propensity score matching on 50 patients for further analysis. Results: The cohort had 100 patients split evenly between the RT and NRT groups. The RT group had higher Overall Survival than NRT (p < 0.046), remaining significant after Propensity Score Matching (PSM) (p < 0.034). Biochemical progression-free survival was also higher in RT vs. NRT (p < 0.033), maintaining significance after PSM (p < 0.042). RT patients reported longer symptom-free time vs. NRT (p < 0.017), though this difference did not persist post-PSM (p < 0.249). Post-PSM analysis showed higher loco-regional progression-free survival in the RT group vs. NRT (p < 0.049). Conclusions: Our study shows improved overall survival in the high-metastatic-burden group when adding RT to the standard treatment of choice, which persists after propensity score matching. The RT group in the entire cohort also demonstrated a reduction in progressing urinary symptoms and biochemical progression-free survival. These findings highlight radiotherapy's potential as a viable treatment in these patients. However, prospective studies with comprehensive data collection are needed to fully address this topic.