Debate 2: Primary Localized Prostate Cancer: The Case for Whole-Gland Brachytherapy Boost

Whole gland brachytherapy (BT) boost in combination with external beam radiotherapy (EBRT) improves biochemical relapse free survival (bRFS) for intermediate- and high-risk prostate cancer (PCa). Three randomized control studies (RCT) have demonstrated superiority over EBRT alone, and a meta-analysis alongside updated long-term data demonstrates an ongoing benefit with whole gland BT boost. There are concerns that improved tumor control comes at the expense of late genitourinary (GU) and gastrointestinal (GI) toxicities. Although studies investigating the role of a focal boost to the dominant intraprostatic lesion (DIL) have been conducted with promising outcomes and low toxicity rates, the multifocal and multiclonal nature of PCa as well as lack of head-to-head RCTs makes it difficult to justify the use of focal boost in place of whole gland boost. Similarly, many studies have used various EBRT techniques to deliver boost treatment despite the radiobiological advantages and stronger evidence base advocating for BT. On this basis, as well as the challenges of precise delineation of the DIL, whole gland BT boost in combination with EBRT remains the optimal radical radiotherapy regime for locally advanced PCa.