Outcomes With Radiation Therapy as Primary Treatment for Unresectable Cutaneous Head and Neck Squamous Cell Carcinoma

Aims: Unresectable cutaneous squamous cell cancer of the head and neck (HNcSCC) poses treatment challenges in elderly and comorbid patients. Radiation therapy (RT) is often employed for locoregional control. This study aimed to determine progression-free survival (PFS) and overall survival (OS) outcomes achieved with upfront RT in unresectable HNcSCC. It also aimed to determine the impact of varying RT dose regimes on disease outcomes.

Methods: A retrospective cohort study was conducted of patients with unresectable HNcSCC treated with first-line RT at a tertiary teaching hospital in Sydney, Australia between 2015-2024. Patient, disease, treatment and follow-up data were extracted from the electronic records.

Results: Of 36 patients, 67% were male, median age was 81 years, and median Charlson Comorbidity Index was 6.5. Median follow-up was 21 months. 83% of RT courses were delivered via intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT). Objective response rate was 97%. Patients were grouped into low-dose RT receiving biologically equivalent dose (BED) <60Gy (n = 18) or high-dose RT (BED ≥ 60Gy, n = 18). Infield progression-free survival (PFS) at 6 months was 56% and 78%, respectively. Overall survival at 6 months was 83% and 89%, and by 24 months 31% and 65%, respectively.

Conclusion: RT is an efficacious treatment that can be tailored to individual patient contexts with unresectable HNcSCC. It has a high response rate overall, with higher doses producing longer disease control. Some patients with poorer functional status receiving low-dose RT can still achieve a sustained response. Future comparisons of outcomes and cost-effectiveness with emerging treatments such as immunotherapy will be important in guiding management for frail patients with unresectable disease.