Prostate Cancer-related Events in Patients with Synchronous Metastatic Hormone-sensitive Prostate Cancer Treated with Androgen Deprivation Therapy with and Without Concurrent Radiation Therapy to the Prostate; Data from the HORRAD Trial

Abstract

Background and objective: A survival benefit was demonstrated for patients with low-volume synchronous metastatic hormone-sensitive prostate cancer (mHSPCa) when local radiotherapy to the prostate was added to androgen deprivation therapy. This study aims to determine the incidence of prostate cancer-related events and treatments in those who received and those who did not receive external beam radiotherapy for mHSPCa.

Methods: The HORRAD trial is a multicentre randomised controlled trial recruiting originally 432 patients with mHSPCa diagnosed between 2004 and 2014. In a second updated analysis, 328 patients were studied retrospectively for local and nonlocal prostate cancer-related events and treatments. Outcome measurements included the incidence and treatment of local (bladder outlet or ureter obstruction, catheterisation, surgical intervention, ureteric stents, and nephrostomy tubes) and nonlocal (blood transfusions, hospitalisations, and treatment for painful bone metastases) events. Differences between groups were compared using crude and adjusted logistic regression, while time to occurrence of local events was assessed with Kaplan-Meier curves and Cox regression analysis.

Key findings and limitations: A significant difference in the incidence of local events was observed: 30 events in the radiotherapy group versus 50 in the nonradiotherapy group (p = 0.04). Time to occurrence of local interventions was significantly longer in the radiotherapy group (hazard ratio 0.61, 95% confidence interval 0.37-0.99, p = 0.04). The study's limitations include its retrospective nature.

Conclusions and clinical implications: Local radiotherapy to the prostate prolongs local event-free survival significantly and reduces local prostate cancer-related interventions in patients with mHSPCa.

Keywords: Local control; Local radiotherapy; Metastatic prostate cancer; Primary tumour.