Real world outcomes of high dose hypo-fractionated radiation therapy for mucosal head and neck cancer in patients unsuitable for curative treatment.

Background: A significant minority of patients in high income countries with symptomatic mucosal head and neck squamous cell carcinomas (HNSCC) warrant treatment of their locoregional disease but are not suitable for standard high dose radiation therapy (RT) with or without concurrent chemotherapy. This study aimed to determine the factors associated with locoregional control (LRC) and survival for patients undergoing high dose palliative-intent RT, to help improve patient selection for this treatment approach. Materials and methods: This retrospective cohort study included all patients with HNSCC who received high dose RT (50-55 Gy in 20 fractions over 4 weeks) with palliative-intent from 2007-2024 at an academic Australian cancer centre. Results: 53 patients comprised the study cohort, of which 92% completed the prescribed RT in full. Median overall survival was 21.6 months and in-field LRC at 12-months was 80%. Acute toxicities were low [Common Terminology Criteria for Adverse Events (CTCAE) grade 3 mucositis 17%, local pain 6.5%, and dysphagia 4.4%, with no grade 4-5 toxicities], with resolution of majority by six months post RT (7% grade 2, no grade 3 or higher toxicities). Larger primary tumours (T3 or T4) and more advanced stage disease [American Joint Committee on Cancer (AJCC) stage III-IV, 8th edition] were associated with worse in-field LRC. Conclusions: High dose palliative-RT in patients with mucosal HNSCC not suitable for definitive chemoradiotherapy provided durable local control with low toxicities after 12 months. In-field locoregional failures were more likely for more advanced disease.