2721 - Outcomes of Patients with Sinonasal Tumors Treated with Beam Scanning Proton Therapy

10:45am - 12:00pm PT

Hall F

Screen: 19

POSTER

Presenter(s)

Alexey Cherchik, Resident Physician - Paul Scherrer Institute, Villigen, Aargau

A. Cherchik¹, I. Kotov², D. C. Weber^1,3, and B. Bachtiary¹; ¹Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland, ²Department for Radiology, Kantonsspital Baden, Baden, Switzerland, ³Department of Radiation Oncology, Inselspital Bern University Hospital and University of Bern, Bern, Switzerland

Purpose/Objective(s): Sinonasal tumors (SNTs) are a histologically diverse group of malignancies that, due to their proximity to critical structures, can particularly benefit from proton therapy over conventional radiation. With growing evidence supporting proton therapy for head and neck cancers, we retrospectively analyzed outcomes in patients with SNT treated with Pencil Beam Scanning Proton Therapy (PBSPT) at our institution. This represents the largest series of SNT patients treated with PBSPT to date.

Materials/Methods: We reviewed 85 SNT patients who underwent PBSPT for between July 2000 and December 2023. The majority (n= 53; 62.4%) had locally advanced tumors (i.e. cT4a/b). Resection was the primary treatment in 48 (56.5%) patients followed by adjuvant PBSPT. The most common histologies were squamous cell carcinoma, olfactory neuroblastoma, and adenoid cystic carcinoma (n=18 each), followed by sinonasal undifferentiated carcinoma (n=15; 17.6%). The median age at the start of PBSPT was 53.9 years (range 19.7 -82.4), with a median follow-up of 36.8 months. Most patients received neoadjuvant chemotherapy (n= 53; 62.4%), and 34 (40%) had concomitant chemotherapy. The median total applied dose was 70 Gy (RBE) (range: 59.4–77.4), with a median number of fractions of 35 (range: 27–43).

Results: After a median follow-up time of 36.8 months, 13 (15.3%) patients presented a local failure. The estimated 3-year local recurrence-free survival was 80.1%. The 3-year overall survival and progression-free survival was 77.5% and 59.6%, respectively. High grade (Grade 3+) early toxicity was observed in 16 (18.8%) patients. Central nervous system (CNS) radiation necrosis occurred in 11 patients (12.9%), with only 3 cases (3.5%) being Grade = 3. Visual toxicity Grade 1 and 2 was reported in 7 patients (8.2%), including one Grade 3 event (1.2%). The estimated 3-year high-grade toxicity-free survival was 81.4%.

Conclusion: PBSPT for SNTs provides promising clinical outcomes, with high rates of local control and overall survival. The acute and long-term toxicity profile is manageable, with severe complications, including CNS necrosis and visual impairment, being relatively rare. This study, which represents the largest series of SNT patients treated with PBSPT to date, underscores the potential of PBSPT as a safe and effective treatment modality for tumors located in anatomically complex and radiation-sensitive regions.