Hypofractionated adjuvant radiotherapy in cutaneous squamous cell and basal cell carcinoma of the head and neck: 50(Gy) in 20 study

To assess clinical outcomes and tolerability of patients with cutaneous squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) of the head and neck region, treated with adjuvant radiotherapy prescribed to a moderately hypofractionated regimen of 50Gy in 20 fractions. Eligibility for this retrospective study included patients with cutaneous SCC and BCC of the head and neck who received adjuvant radiotherapy to a dose of 50Gy in 20 fractions (2.5Gy per fraction) between 1/1/2007 and 31/12/2019 at a tertiary Queensland hospital. Primary endpoint was freedom from local failure (FFLF). Secondary outcomes were loco-regional recurrence-free survival (LRRFS), overall survival (OS) and toxicity rates. Acute toxicities were retrospectively collected and reported according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0. A total of 126 patients were evaluated in this study with a median follow up period of 19.7 months (interquartile range 1.63 to 121.03). The median age was 68.3 years old. Twenty-six patients were immunosuppressed. Predominant histopathology was SCC (63.5%). The majority were staged pT1-2 (74.6%), and clinically or pathologically N0 (96.8%). 122 patients received adjuvant radiotherapy to the primary tumour bed, and four patients received treatment both the primary and nodal region. FFLF was 95.8% and 92.2% at 2 and 5 years, respectively. No statistically significant clinico-pathological factors were prognostic of FFLF. LRRFS was 90.5% at 2 years and 83.1% at 5 years. OS was 88.7% at 2 years and 69.9% at 5 years. Five of the 21 deaths were related to the index cutaneous carcinoma. Grade 3 radiation dermatitis and mucositis occurred in 13.5% and 4.0% of patients, respectively. There were no grade 4/5 toxicities. Four patients required treatment breaks, of which two were planned breaks. No patient required enteral feeding during their RT course. This is the largest series to date evaluating a single moderately hypofractionated adjuvant radiotherapy regimen for cutaneous SCC and BCC of the head and neck. This regimen was associated with high locoregional control and was well tolerated. A moderately hypofractionated course of adjuvant radiotherapy in cutaneous SCC and BCC can be a suitable option to reduce treatment duration. • Current literature includes a wide range of radiotherapy schedules for skin cancers of the head and neck • We observed excellent local control and tolerability in our cohort of uniformly treated patients that required adjuvant radiotherapy • Our results support the use of a moderately hypofractionated schedule of 50Gy in 20 fractions for skin cancers