Stereotactic Body Radiotherapy (SBRT) of Previously Unirradiated Mucosal Head and Neck Squamous Cell Carcinoma (SCC)

To evaluate the efficacy and safety of stereotactic body radiation therapy (SBRT) in previously untreated primary mucosal head and neck cancer (HNC) patients unfit for conventional radiation therapy.

Retrospective analysis of previously unirradiated primary SCC mucosal HNC patients treated with SBRT from 2011 to 2022.

HN SBRT was prescribed to 74 patients (median age: 81 years [52-97]; 85% ECOG 2-3) with 77 primary tumors (62% oral cavity; 64% T3-4 disease). A five-fraction prescription ranging from 35 to 50 Gy (95% received ≥ 40 Gy, 59.7% received ≥ 45 Gy) was delivered twice weekly, with the majority (81%) completing treatment within 14 days and all patients completing treatment. Symptomatic relief was achieved by 84%, including 27.3% with complete symptomatic response. With a median follow-up of 7.3 months, 1-year outcomes were 81% local control, 16% regional recurrence rate, and 12% distant metastasis rate. Median progression-free and overall survival were 6.4 and 8 months, respectively. Acute Grade 3+ toxicity occurred in 36%, primarily mucositis (30%). Late Grade ≥ 3 toxicity was observed in 10% (n = 7), including osteoradionecrosis in 5 patients, with residual or concurrent disease present in 5% (n = 4). PTV > 159 cm³ was significantly correlated with late grade ≥ 3 toxicity (OR = 15.98; p = 0.0041).

High-dose SBRT may deliver high rates of local control and palliation for primary mucosal HNC patients unfit for conventional radiation, but prospective, comparative, high-quality data are needed. A randomized trial (NCT06641791) comparing SBRT to conventional palliative RT in the elderly unfit HNC patient is underway.