Stereotactic body radiotherapy for head and neck skin cancer

To report outcomes of Stereotactic Body Radiotherapy (SBRT) for head and neck skin cancer (HNSC) patients treated at a high-volume center.

A retrospective review of HNSC SBRT patients from 2012 to 2019 was conducted. Kaplan-Meier method was used to estimate local control (LC), locoregional control (LRC) outside of SBRT field, overall survival (OS), progression-free survival (PFS) and late toxicity (LT). Univariate and multivariate analyses were performed. Grade 3-4 acute and late toxicities were reported by the Common Terminology Criteria for Adverse Events v5.0.

One hundred and six medically unfit HNSC patients (112 lesions) were included. Median follow-up was 8 months. Median patient age at diagnosis was 86 years (range: 56-102 years). The majority of patients had advanced disease (overall stage III-IV [n = 90, 85%]) with median gross tumor volumes (GTV) of 31 cm³ (range: 17-56 cm³). Treated sites were: primary (n = 51), nodal (n = 47) or primary plus nodal (n = 8). SBRT doses ranged from 32-50 Gy delivered twice weekly in 4-6 fractions to the gross tumor volume (GTV). One and 2-year LC rates were 78% (69-88) and 67% (53-82), respectively. One-year LRC outside of SBRT field, OS, PFS and LT rates were 72% (62-84), 53% (43-65), 52% (40-62), and 7% (2-17), respectively. Thirty-three patients (31%) developed acute grade ≥ 3 treatment-related toxicity, most commonly dermatitis (n = 31). Nine patients (8%) experienced late grade ≥ 3 toxicity, including 7 grade 3 fibrosis, 1 grade 3 bone radionecrosis and 1 grade 4 skin ulceration. No treatment-related deaths (grade 5) were observed.

SBRT provides durable disease control with acceptable toxicity for medically unfit high-risk HNSC patients unable to undergo standard of care curative treatment approaches.