A Multicenter Prospective Trial of Electronic Skin Surface Brachytherapy (ESSB) for Cutaneous Squamous Cell Carcinoma (SCC) and Basal Cell Carcinoma (BCC): Cosmesis, Quality of Life (QoL) and Adverse Events (AEs)

Abstract

<h3>Purpose/Objective(s)</h3> SCC and BCC are amenable to a variety of treatments. ESSB has emerged as a novel option which enables precise delivery of radiotherapy (RT), potentially limiting side effects. In a prospective multicenter clinical trial, we characterized early outcomes of ESSB, hypothesizing that it affords cosmesis superior to what has been previously reported. <h3>Materials/Methods</h3> Patients ≥60 years old with clinical stage T1N0M0 SCC or BCC were recruited. Patient and clinician-reported cosmesis was evaluated with a previously reported subjective 3 tier system. QoL was assessed by the Skindex-16 (S16) and Skin Cancer Index (SCI). Assessments were performed before treatment and 2, 6 and 12 weeks post-treatment. AEs were assessed using CTCAE v4.0. A primary endpoint was patient-reported cosmesis, with the hypothesis that ESSB would be associated with a 12 week post-treatment patient-report of "good" cosmesis in ≥90% of patients. A sample size of 34 patients was calculated to determine if the rate of "good" cosmesis was superior to a previously reported 73% rate of "good" cosmesis with a type I error rate of 0.07 and a type II error rate of 0.12. Comparisons of QoL before and post-treatment were done using Wilcoxon signed rank tests. <h3>Results</h3> 34 patients were treated with ESSB prescribing 42 Gy in 6 fractions twice or thrice a week to a depth of 3 mm below skin surface. Patients were mostly women (59%); all were white and non-Hispanic. Most were treated for BCC (94%), on the face (97%) and nose (68%). Cosmesis and QoL was collected at 99 of 102 (97%) possible patient-time points. Patient and clinician-reported "good" cosmesis 12 weeks post-treatment was reported in 93% and 97% of cases, respectively. Significant decreases in QoL were noted 2 weeks post-treatment in the symptom and function subscales of the S16, but thereafter significant increases in QoL were noted in almost all subscales of S16 and SCI (see Table). The most severe AEs were grade 3 and occurred in week 3 of treatment (skin pain, 6%) and 2 weeks post-treatment (dermatitis, 42%). All AEs resolved to grade ≤1 by 12 weeks post-treatment. <h3>Conclusion</h3> This prospective study with very complete data collection supports the hypothesis that ESSB is associated with a superior rate of early patient-reported cosmesis compared to previously reported forms of RT for skin cancer. Validated assessments demonstrated a significant improvement in QoL and resolution of moderate early AEs by 6-12 weeks post-treatment and corroborate the observation of favorable cosmesis.