A review of whole gland prostate brachytherapy with focal dose escalation to intra-prostatic lesions: Clinical efficacy and technical aspects

Focal boost to intra-prostatic lesions (IPLs) in radiotherapy could enhance treatment efficacy. Brachytherapy (BT), delivering highly conformal dose with sharp dose gradients emerges as a potentially optimal approach for precise dose escalation to IPLs. This study aims to consolidate clinical and planning studies that implemented whole gland prostate BT and focal dose escalation to IPLs, with the view to synthesize evidence on the strategy's effectiveness and variability. In this review, we identified nine clinical studies and ten planning/simulation studies focusing on whole gland prostate BT with IPL dose escalation. From the clinical studies, the use of whole gland prostate BT with focal dose escalation in combination with external beam radiotherapy (EBRT) appears to be a safe and effective 21 form of treatment for men with T1b - T2c prostate cancer with average five-year biochemical failure22 free survival (BFFS) of 94 % (range 81.1 %-100 %) and minimal grade three toxicities reported. Both clinical and planning studies exemplified the high level of focal dose escalation achievable using BT with a mean IPL D90 % of 132 % and 146 %, respectively (expressed as a % of the whole gland prescription dose). There was considerable variation in the reporting of clinical and technical data in the identified studies. To facilitate a more widespread and uniform adoption of the technique, recommendations on essential and desirable items to be included in future studies incorporating whole gland prostate BT with focal boost to IPLs are provided.