Two different sizes of Valencia applicators in non-melanoma skin cancer treatment with iridium-192 high-dose-rate brachytherapy

Introduction
The aim of this retrospective study was to analyze tumor control, toxicity, and aesthetic outcome of patients affected by non-melanoma skin cancer (NMSC) and treated with iridium-192 (192Ir) high-dose-rate (HDR) brachytherapy (BT) using Valencia applicators at the Division of Radiotherapy, University of Pisa.

Material and methods
From June 2015 to December 2020, 95 NMSC patients, including 61.5% basal cell carcinoma and 38.5% squamous cell carcinoma patients, with median age of 83 years (range, 32-96 years) were treated. In total, 182 lesions with a diameter ≤ 25 mm (median, 12 mm) and a depth ≤ 4 mm, located in scalp (19.2%), face (20.9%), chest (8.8%), nose (16.5%), ear (15.4%), and extremities (19.2%) were analyzed. All lesions were treated with 192Ir-based HDR afterloader using Valencia applicators. 105 lesions (57.7%) were treated with applicator of 20 mm and 77 lesions (42.3%) with applicator of 30 mm in diameter, depending on the size of lesions. Prescribed dose was 40 Gy in 8 fractions (5 Gy/fraction) delivered 2-3 times a week. Biological effective dose (BED) was ≈ 60 Gy.

Results
The median follow-up was 14 months (range, 3-59 months). The 2-year local control rate was 96%. According to common terminology criteria for adverse events (CTCAE v. 5.0), G1-G2 acute toxicities included dermatitis (22.0%) and pain (8.2%). The most common G1 late toxicities were hypopigmentation (27.5%) and fibrosis (8.2%), and G2 late toxicity included ulceration (0.5%). No G3 or higher acute or late toxicities were reported. Excellent cosmetic results were observed in 77.5% of the lesions, with one only (0.5%) reported as a poor cosmetic result (ulceration refractory to therapy).

Conclusions
HDR-BT using Valencia applicators is a safe, effective, and well-tolerated treatment modality for NMSC, and can be considered a good alternative for treatment, especially in elderly patients who are often unfit for surgery.