Unsealed188 Rhenium Resin Brachytherapy in Non-Surgical Candidates With Refractory Basal Cell Carcinoma: Clinical Outcomes.

Introduction: High-dose brachytherapy using a non-sealed 188Rhenium resin (188Re) is a new treatment option for difficult-to-treat basal cell carcinoma (BCC) that ensures a radical oncological outcome minimizing side effects. Objectives: The aim of this retrospective study was to evaluate the clinical efficacy of high-dose standardized brachytherapy using an unsealed 188Re in the management of difficult-to-treat BCCs and to evaluate the risk factors of relapses. Methods: Between October 2017 and December 2022, patients affected by difficult-to-treat BCC were selected. Inclusion criteria: histologically proven cutaneous BCC; thickness invasion no deeper than 3 mm; lesion located in the scalp, face, ears, or fingers or other areas in which surgery would have been difficult to perform or to destroy with scarce cosmetic-functional result; contraindication or refusal of surgery. All patients performed follow-up visits with videodermoscopy every 4-6 months. Results: Sixty-four consecutive patients affected by 82 histologically proven high-risk BCCs, were enrolled: 60 were nodular, 9 sclerodermiform, and 13 superficial. Average follow-up was 24 months. Brachytherapy with 188Re resin achieved a complete response in 93% of "difficult-to-treat" BCCs, with relapses occurring on average 24 months after the initial treatment. No statistically significant difference in response to brachytherapy was found in the anatomical area treated, size of the tumor, or previously treated vs. naive BCCs. The sclerodermiform histotype had a 7-fold higher risk of recurrence than nodular histotype; recurrence occurred approximately 12 weeks earlier. Conclusion: High-dose 188Re brachytherapy is a noninvasive, easy to perform, well-tolerated approach to treat difficult BCC when surgery or other therapy techniques are not feasible.