Marieke van Son

63 FOCAL SALVAGE TREATMENT: A NARRATIVE REVIEW INTRODUCTION Prostate cancer is the most diagnosed male cancer in developed countries. Frequently diagnosed at an early stage, with opportunistic PSA-screening increasing the incidence, the search for optimal and patient-tailored treatment is of growing significance. In the setting of localized recurrent prostate cancer after primary whole-gland radiotherapy, standard of care now consists of palliative androgen deprivation therapy (ADT). This only has a temporary suppressive effect and is associated with harmful side-effects. On the other hand, treatments with curative intent such as salvage prostatectomy or whole-gland radiotherapy also convey serious toxicity risks and should only be offered to highly selected patients [1]. This leaves a gap in the treatment arsenal for radiore- current prostate cancer. Here, focal ablative treatment might meet the need: with lower toxicity risks, it could postpone palliative hormonal treatment or perhaps even avoid it altogether. Within this narrative review, an overview is provided of the developments in primary prostate cancer care, current strategies on how to deal with localized prostate cancer recurrences and future perspectives with respect to focal salvage treatment. Whole-gland primary radiotherapy For whole-gland treatment of intermediate- to high-risk prostate cancer in the primary setting, radiotherapy has evolved as a suitable modality. It is comparable to prosta- tectomy in terms of cancer control, while both are associated with their respective side-effects [2]. Several developments over the last decades have increased the use of radiotherapy for the primary treatment of prostate cancer. Intensity-modulated ra- diation therapy (IMRT) and volumetric modulated arc therapy (VMAT) are increasingly adopted as external beam radiation therapy (EBRT) techniques, using fiducial gold markers for position verification. Both are able to substantially reduce the dose to surrounding organs at risk (in particular rectum and bladder) due to a more confor- mal dose distribution [3,4]. Although radiation therapy traditionally entailed a lengthy treatment with smaller daily fractions over 6-7 weeks’ time, hypofractionation seems to provide comparable tumor control, against acceptable toxicity profiles [5-9]. The rationale behind using higher dose in fewer fractions comes from data describing a lower α/β-ratio of prostate cancer than previously thought. Despite ambiguous recom- mendations from different large trials, hypofractionated radiotherapy is increasingly adopted in guidelines worldwide [10]. While external beam techniques are generally delivered fractionated, internal radi- ation using brachytherapy is increasingly performed in a single procedure. Originally, low-dose-rate brachytherapy (using Iodine-125 seeds) was mainly used for low- to in- termediate-risk patients. Nowadays, there is an increase in the treatment of higher-risk disease with high-dose-rate brachytherapy, providing comparable cancer control rates to other primary treatments [11-13]. As compared to Iodine-125 seeds, high-dose-rate brachytherapy offers the advantage of higher dose control by the approach of adjust- ing source dwell times and positions. The steep dose decline of brachytherapy makes 4