Abstract
BACKGROUND: Local control of high-risk sinonasal squamous cell carcinoma (SCC) remains challenging and often involves significant morbidity. Management of the node-negative neck is still debated. This study evaluated treatment outcomes, neck management strategies, and toxicity rates in patients treated with intensity-modulated radiotherapy (IMRT) combined with a carbon ion boost. METHODS: We evaluated 43 patients with sinonasal SCC treated with IMRT and carbon ion boost between 2011 and 2019. Follow-up followed head and neck cancer guidelines. Patient and tumor characteristics, treatment outcomes, and toxicity (per CTCAE v5.0) were assessed. Statistical analysis was performed using R version 4.1.0. RESULTS: Median age was 64 years (range 19-83). Most patients had T3-4 tumors (n = 36; 83.7 %) and were clinically node-negative (n = 40; 93.0 %). The predominant regimen was 24 Gy (RBE) carbon ion boost in 8 fractions, followed by 50 Gy IMRT in 25 fractions. Postoperative RT was delivered to 25 patients (58.1 %), while 18 (41.9 %) received definitive RT. Elective or therapeutic neck dissection was performed in 10 patients (23.3 %), none showing lymph node metastases. In total, 22 distinct cervical lymph node treatment strategies were applied. Median follow-up for overall survival (OS) was 25.1 months. Tumor recurrence occurred in 11 patients (25.6 %), primarily due to local failure (n = 7; 63.6 %). OS and local progression-free survival (L-PFS) at 12/24 months were 93.0 %/89.3 % and 88.4 %/79.0 %, respectively. Grade III acute and late toxicity occurred in 9.3 % and 4.7 % of patients, respectively. No grade IV toxicity was reported. Mean numbers of grade I-II toxicities per patient were 4.8 (acute) and 2.4 (late). CONCLUSION: IMRT with carbon ion boost provides promising OS and local control in high-risk sinonasal SCC. The management of the node-negative-neck was highly individualized. Toxicity was acceptable and may be further reduced by tailoring cervical lymph node treatment in selected patients.