Chapter 1 22 salvage treatment. However, the incidence of moderate and severe (grade ³ 3) toxicity often seems to be lower. A recent review showed that grade 3 GU toxicities ranges from 0-10% for all focal salvage modalities.83 With respect to oncological outcomes, results seem comparable between the different focal salvage modalities. For example, for focal salvage cryotherapy, biochemical recurrencefree survival (bRFS) ranges from 48.1-95.3% at 1 year, to 48.1-72.4% at 2 years, and 46.5-54.4% at 5 years.100–106,111 For focal salvage high-dose-rate brachytherapy (FS-HDR-BT), bRFS ranges from 95.2% at 1 year, to 61-92% at 2 years, and 41.8-61% at 3 years.95,97–99,112 bRFS seems somewhat higher (61% at 3 years) in the study by Murgic et al.95, who used two fractions of 13.5 Gy, compared to those investigating a single fraction HDR treatment (41.8% and 46% at 3 years).98,99 However, as stated before, differences in inclusion criteria and thus risk groups make it difficult to draw definite conclusions regarding differences in efficacy from these small studies. MRI-guided focal salvage high-dose-rate brachytherapy At the Department of Radiation Oncology of the UMC Utrecht, several prospective studies were initiated to investigate the efficacy and safety of MRI-guided FS-HDR-BT, including the PRECISE study (NTR7014). In these studies, patients were treated in a single fraction with a dose of 19.0 Gy to the CTV. The CTV consisted of the mp-MRI visible tumour (GTV) with a 5 mm isotropic expansion, staying within the prostate boundaries and excluding the urethra (Figure 5). The FS-HDR-BT treatment is extensively described in earlier publications.92 In short, pre-treatment imaging (3 T MRI and PSMA-PET/CT) is acquired to identify the target and OARs and to create the Figure 5 – Transversal image of contours used for focal salvage high-dose-rate brachytherapy (FS-HDR-BT) treatment of a lesion in the right hemi-prostate. The Gross Tumour Volume (GTV), Clinical Target Volume (CTV), prostate, urethra, and rectum contours are displayed.
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