Significant interruptions in radiotherapy during curative treatment for prostate cancer are correlated with poorer oncological outcomes

To investigate the effects of radical radiotherapy (RT) relevant interruptions (RRI), single (sRRI) or multiple (mRRI), on Biochemical Failure-Free Survival (BFFS), Metastases-Free Survival (MFS) and Overall Survival (OS) in prostate cancer (PCa) patients. We conducted a retrospective analysis involving 383 patients diagnosed with prostate cancer (PCa) who received radical RT between March 2013 and April 2021, with doses ranging from 60 to 80 Gy (median dose 76.0 Gy), either alone or in combination with androgen deprivation therapy. The study aimed to evaluate the effects of sRRI and mRRI radiation-related interruptions on BFFS, MFS, and OS using the Kaplan-Meier method. Additionally, we adjusted for relevant prognostic factors using three multivariate Cox regression proportional hazard models. In the univariate analysis, it was observed that patients who experienced unexpected RRIs (50.1%: 35.5% sRRI and 14.6% mRRI), resulting in a median overall treatment time prolongation of five days, exhibited a higher incidence of biochemical failure (BF) and metastases (Met). However, no difference was observed in OS. In the multivariate analysis, it was found that RRIs were significantly associated with increased hazards of BF (sRRI, aHR: 4.61, 95% CI: 2.80-7.60; mRRIs, aHR: 9.92, 95% CI: 5.61-17.54), Met (sRRI, aHR: 4.20, 95% CI: 1.97-8.94; mRRI, aHR: 7.01, 95% CI: 2.94-6.71), and all-cause mortality (mRRI, aHR: 1.89, 95% CI: 1.18-3.03). sRRIs were associated with both lower BFFS and MFS, while mRRIs with both BFFS, MFS and OS.