Learning Curve Analysis of Alpha DaRT Implantation for Cutaneous Malignancies: A Single-Surgeon Experience

Background/Objectives: Diffusing Alpha-emitters Radiation Therapy (Alpha DaRT) is a novel interstitial radiotherapy technique that delivers high-linear energy transfer alpha radiation directly into tumor tissue. As with any new procedural oncology intervention, operator experience may influence procedural efficiency and reproducibility. This study evaluated the learning curve associated with Alpha DaRT implantation for cutaneous malignancies using procedure duration as a surrogate measure of procedural efficiency. Methods: A retrospective learning-curve analysis was conducted using procedural data from a prospective, single-arm clinical trial (NCT03889899). Alpha DaRT implantation procedures performed by a single surgeon in 24 patients with basal-cell carcinoma and squamous-cell carcinoma were analyzed. Given the variability in procedure duration due to lesion size, duration per applicator was used as a standardized endpoint for learning-curve assessment. Surgeon experience was defined by sequential procedure number, and sequential regression analyses evaluated changes over time. Results: Twenty-six Alpha DaRT procedures were performed between October 2020 and February 2025. A moderate negative correlation was observed between procedure number and duration (Spearman’s r = −0.57, p = 0.002). The greatest reduction in duration was observed after the first five procedures, with mean duration per applicator decreasing from 221 s in the initial cases to 153 s thereafter. Tumor volume was independently associated with longer procedural duration (p < 0.001), while lesion type, location, and number of applicators were not. Conclusions: Alpha DaRT implantation demonstrated a short initial learning curve when assessed by procedural efficiency, with substantial improvement observed after approximately five procedures. These findings suggest that procedural familiarity develops rapidly; however, validation across multiple operators and institutions is needed to determine the generalizability of these results and inform future training standards.