Biochemical Outcome in Metastatic Prostate Cancer Patients Following Prostate-Directed Radiotherapy

Abstract Background The role of cytoreductive local radiotherapy (RT) in metastatic prostate cancer has recently been established. This study aimed to evaluate the biochemical outcome of local RT in metastatic prostate cancer. Methods This randomized controlled phase II study conducted at the Clinical Oncology Department, Suez Canal University Hospital. Eligible participants were de-novo or metachronous metastatic prostate cancer patients with Eastern Cooperative Oncology Group performance status of 0–2. Participants were randomized to receive either cytoreductive prostate-directed RT in addition to standard care or standard care alone. The conventional radiation schedule of 70 Gy/35 fractions or the hypofractionated schedule of 55 Gy/20 fractions were delivered. The primary endpoint was biochemical progression-free survival (BPFS), and secondary endpoints included clinical response, and overall survival (OS). Survival and post-hoc analyses were performed using Cox regression and the Kaplan-Meier method with the log-rank test. Results Between November 23, 2020, and November 21, 2022, 70 patients were enrolled in this study. Of them, 34 patients were assigned to the prostate radiotherapy group, and 29 patients were assigned to the control group. At a median follow-up of 12 months, the median BPFS has not been reached for the prostate radiotherapy group compared to 4.067 months for the control group (HR: 0.147, p  < 0.001). Subgroup analysis showed that the median BPFS was statistically significantly correlated with low-volume (95% CI, 0.004 to 0.262, p  = 0·001) and hormonal-sensitive metastatic disease (95% CI, 0.010 to 0.192, p  < 0·001). The median OS was 16.33 months for the prostate-radiotherapy group compared to 11.33 months for the control group (HR: 0.313, p  = 0.003). Conclusion Prostate-directed RT improved BPFS and OS in metastatic prostate cancer patients, particularly in those with low volume and hormonal-sensitive disease. Trial Registration: This trial is registered on (27/4/2023) with pactr.samrc.ac.za, PACTR202305854600529, URL: https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=25510