Radiation segmentectomy with resin microspheres for hepatocellular carcinoma: a state-of-the-art review highlighting evidence gaps and future research needs

INTRODUCTION: Radiation segmentectomy (RS) has emerged as a promising approach for hepatocellular carcinoma (HCC), particularly when high tumor doses are achieved. While the clinical utility of ablative doses with glass microspheres is well established, data on resin microspheres remain scarce and inconsistent. This state-of-the-art review aims to provide a descriptive, hypothesis-generating overview of the available evidence and to highlight key gaps in the literature. METHODS: A structured search of PubMed and Embase was conducted to identify clinical studies, technical reports, and reviews evaluating RS using resin microspheres in patients with HCC. Inclusion was limited to studies reporting dosimetric data or clinical outcomes following high-dose delivery. Both published and unpublished sources were considered to ensure a comprehensive overview. RESULTS: Six publications met the inclusion criteria: four studies with primary clinical data and two narrative reviews. Most were retrospective and single-center, with considerable heterogeneity in methodology and outcome reporting. Reported tumor doses varied widely, and no prospective study has validated safety or efficacy thresholds to date. Nevertheless, selected studies suggest that resin microspheres may achieve tumoricidal doses (> 300 Gy), with encouraging response rates and acceptable safety profiles in highly selective settings. CONCLUSION: The use of resin microspheres in radiation segmentectomy represents a promising, yet underexplored, therapeutic strategy in HCC. However, the current evidence base is limited, heterogeneous, and not suitable for definitive clinical conclusions. This review is intended to frame the current evidence landscape and generate hypotheses, supporting the need for prospective, standardized investigations to define optimal dosimetry and guide future research.