MRI-guided Dose-escalated Salvage Radiotherapy for Bulky Bladder Neck Recurrence of Prostate Cancer

Abstract

Nearly 30% of patients treated with radical prostatectomy for prostate cancer ultimately develop biochemical recurrences, and nearly a quarter of men with nonpalpable biochemical recurrences have gross local recurrences identified with magnetic resonance imaging (MRI). The only curative intervention for patients with recurrent disease after radical prostatectomy is salvage radiotherapy - this is particularly true for patients with gross local recurrences. Furthermore, even in patients with an incurable metastatic disease, a local recurrence can be the source of significant morbidity and should be addressed. Delivering a sufficient dose of radiation in the postoperative setting to control gross disease while minimizing toxicity poses a significant technical challenge. Because of the inherent uncertainty in the verification of gross disease positioning with standard onboard imaging technologies, large margins must be used. Larger margins, in turn, will lead to larger volumes of tissue receiving high doses of radiation, potentially increasing long-term toxicity. Herein, we present the case of a patient with a bulky gross recurrence (>40 cm3) at the bladder neck and synchronous metastatic disease who was referred for salvage radiotherapy after a multidisciplinary consensus recommendation to pursue local therapy for mitigating urinary morbidity from the bulky tumor. The case illustrates the utilization of MRI-guided radiotherapy to allow significant margin reduction, thereby facilitating the delivery of an escalated dose of radiotherapy to a bulky recurrence.