Updated results of 3,050 non-melanoma skin cancer (NMSC) lesions in 1725 patients treated with high resolution dermal ultrasound-guided superficial radiotherapy, a multi-institutional study.

Background: Image-guided superficial radiation therapy (IGSRT) using a high resolution dermal ultrasound, is becoming a non-surgical highly effective treatment option for non-melanoma skin cancer (NMSC). In a previous study, we reported results from a multi-institutional study of 1616 patients with 2917 NMSC lesions treated with IGSRT showing a 99.3% rate of local control (LC) with mean follow-up of 16.06 months.

Methods: In this study, we analyze 133 additional lesions from 93 patients, as well as update previous findings with a longer follow-up duration, and perform subgroup analysis and Kaplan-Meier statistics. A retrospective analysis of 1709 patients with 3,050 Stage 0, I, and II NMSC lesions treated from 2017 to 2020 was performed.

Results: With image guidance, lesions received a median of 20 fractions of 50, 70, or 100 kilovoltage(kV) IGSRT. Average follow-up was 25.1 months with a maximum follow up of 65.6 months for the entire cohort. Sixty-eight patients expired, with deaths due to unrelated causes, who had no-evidence of disease (NED) at last follow-up prior to death, leading to Disease-Specific-Survival of 100% (Overall survival was 96%). Absolute LC of 99.2% was achieved in 3,027 of 3,050 lesions with overall absolute LC for BCC, SCC, and SCC-is being 99.0%, 99.2%, and 99.8%, respectively. As of January 2022, no other late complications were found.

Discussion: These updated results demonstrates that IGSRT should be considered a first-line option for the non-surgical treatment of NMSC as it continues to achieve low complication rates while maintaining a high level of LC.