Marieke van Son

107 QOL AFTER ULTRAFOCAL SALVAGE HDR-BRACHYTHERAPY INTRODUCTION As a result of treatment innovations and increased cancer survival, more attention is directed towards patient-reported outcomes such as health-related Quality of Life (HR- QoL). This trend is especially relevant for prostate cancer, with decreasing mortality rates in most countries despite increasing incidences(1). Depending on tumor stage, prostate cancer recurrences occur in 10-50% of patients 10 years after external beam radiotherapy (EBRT)(2). Most of these patients are treated with (delayed) androgen deprivation therapy (ADT)(3), which is a temporary suppressive treatment associated with significant side effects and deterioration of HR-QoL(4). Al- though various whole gland salvage treatment modalities are available such as radical prostatectomy, low-dose-rate brachytherapy (LDR-BT), cryotherapy and HIFU, these are unpopular due to high failure and toxicity rates(5). Although salvage prostatectomy and HIFU are associated with higher urinary incontinence rates (40-50%) than salvage cryotherapy or brachytherapy (7-12%), all modalities have high impotence (±75%) and urethral stricture rates (±20%), and 45-55% of patients experience a relapse after 4 years(6). Whole-gland salvage irradiation causes toxicity by accumulation of dose to the surrounding organs at risk. Toxicity reduction is anticipated if the target is reduced from the whole gland to the tumor area alone. Since imaging advancements such as magnetic resonance imaging (MRI) and PSMA-PET/CT have improved detection of the exact tumor location, focal treatment is now clinically feasible(7, 8). Reviews of the available literature on focal salvage treatments (including focal brachytherapy, HIFU and cryotherapy) have consistently shown that they are well tolerated with very limited severe genitourinary and gastro-intestinal toxicity (<5%) and with encouraging biochemical control rates (48-72% after 3 years)(9, 10). The radiotherapy department at the University Medical Centre Utrecht has a 1.5T MRI high-dose-rate brachytherapy (HDR-BT) facility. Here, ultrafocal treatment of recurrent prostate cancer is performed by internal irradiation of the tumor under MRI-guidance. Due to the steep dose fall-off in brachytherapy, a high dose can be applied to the tumor while the surrounding healthy tissue receives low radiation exposure. It is therefore ex- pected that patients experience less side effects and maintain their HR-QoL. Providing a detailed view on the patient’s perspective of this treatment, the current study aims to investigate prostate cancer-specific HR-QoL after ultrafocal salvage HDR-BT and to explore predictive factors that may impact HR-QoL. MATERIAL AND METHODS Patients Between July 2013 and March 2018, the first consecutive 100 patients with localized recurrent prostate cancer after primary radiotherapy were treated with ultrafocal sal- vage HDR-BT. Treatment was either performed within an institutional review board (IRB)-approved prospective study (Netherlands Trial Register [NTR] number 6123 or 6