An Update of Stereotactic Body Radiotherapy (SBRT) for the Palliation of Unirradiated Mucosal Head and Neck Squamous Cell Carcinoma (SCC)

Abstract

We report the treatment outcomes of palliative Stereotactic Body Radiation Therapy (SBRT) in patients with primary mucosal head and neck cancer (HNC) who were not eligible to receive conventional radiation therapy (RT). This is a retrospective study that reviewed the medical records of patients with primary SCC mucosal HNC who were treated with SBRT between 2011 and 2022. Patients with other histologies, skin cancer, parotid tumors, or recurrent previously irradiated tumors were excluded from the study. A total of 74 patients and 77 tumors were treated with SBRT in this cohort. The median age in the study was 81 (52-97) years and the median follow-up was 7.2 months. The most common site of HNC was the oral cavity (62%), followed by the oropharynx (18%), hypopharynx (8%), larynx (5%), nasal cavity/sinonasal cancer (3%), and unknown primary (1%). T3-4 lesions were found in most patients (76%). SBRT doses ranged from 35-50 Gy in 5 fractions, and the most common prescription dose was ≥45 Gy in 5 fractions (60%) for the GTV prescription. An elective nodal volume of 25 Gy in 5 fractions was infrequently (17%) used. Most patients (81%) who were treated twice a week completed in ≤14 days. The predominant symptoms at presentation were: pain (41%), mass effect (39%), dysphagia/odynophagia (14%), headache/nasal obstruction (1.4%), bleeding (1.4%), stridor (1.4%), asymptomatic (1.4%), and unknown (1.4%). 84% of patients had symptomatic response to treatment with 24% of them having complete symptom response. Cumulative incidence of local failure (LF) was 6.7% and at 6 months and 17.9% at 12 months, respectively. Cumulative incidence of distant metastasis was 7.3% and 10.5% at 6 and 12 months. Cancer was the most common cause of death in 29 patients (51%). The median overall survival (OS) was 8 months with 6 and 12-month OS rates of 67% and 36%, respectively. 39% of patients developed acute G3 toxicity, including 30% with G3 mucositis, 5% with G3 dysphagia, and 4% with G3 dermatitis. A crude rate of late G ≥3 toxicity was observed in 11% of patients including (5%, n = 4) with osteoradionecrosis, and a single case of dysphagia, soft tissue necrosis, supraglottic ulceration, and mucosal necrosis. This study highlights the feasibility of SBRT as a treatment option for primary mucosal head and neck cancer patients who are not eligible for conventional radiation therapy. The results indicate that SBRT was effective in achieving local control and symptom relief, but larger prospective studies are needed to confirm the findings. The Canadian Cancer Trials Group has endorsed HN-13, a randomized control trial comparing HN SBRT to palliative RT.