Brachytherapy for rectal cancer: An overview of clinical competency development in contemporary practice.

High-dose-rate (HDR) brachytherapy for rectal cancer is an evolving modality that integrates advanced imaging, personalized applicator design, and multidisciplinary coordination to support organ preservation and improve patient outcomes. As interest in rectal brachytherapy grows-driven by technological innovation and emerging clinical evidence-there is a critical need to define the competencies required for safe and effective practice. This Clinical Competency Review outlines contemporary approaches to HDR rectal brachytherapy, including patient selection, treatment planning, applicator technologies, and quality assurance. It complements existing training frameworks by proposing structured milestones adapted from the Accreditation Council for Graduate Medical Education and informed by international consensus. By delineating procedural expectations and knowledge domains, this document aims to support the development of standardized training pathways and promote high-quality implementation of rectal brachytherapy across diverse clinical settings.