3689 - Nasal Cavity Malignancies Treated with Definitive Proton Therapy: A Single Institutions Experience

N. P. Mankuzhy¹, F. Yang¹, N. Riaz¹, Y. Yu¹, I. Ganly², S. Patel², L. Dunn³, L. Michel³, D. G. Pfister³, E. Sherman³, M. Cohen², and N. Y. Lee¹; ¹Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, ²Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, ³Department of Medical Oncology, Memorial Sloan Kettering Cancer Center, New York, NY

Purpose/Objective(s): Nasal cavity malignancies are traditionally treated with surgery and adjuvant radiotherapy (RT) with or without chemotherapy. Surgical resection for anteriorly based tumors may involve partial or total rhinectomy with potential negative impacts on cosmesis and quality of life. Further, these tumors may be unresectable on presentation. We reviewed our institutional experience of treating mucosal nasal cavity tumors with definitive RT using proton therapy without surgery. Materials/

Methods: Nasal cavity tumors treated at our institution that received definitive proton therapy or proton therapy boost with or without chemotherapy were included. Patients with esthesioneuroblastoma, cancers originating from the paranasal sinuses or nasopharynx, or who underwent oncologic resection were excluded. Overall survival (OS), rhinectomy-free-survival (RhFS), and cumulative incidence of loco-regional recurrence (LR) were measured from diagnosis date. Analysis was completed in R version 4.3.2.
Results: During 2013-2023, 28 patients were included. Among these, 17 patients were those who declined rhinectomy and 11 patients were those who had unresectable disease. The entire course of RT was given with proton therapy (23) or as a boost after intensity-modulated radiation therapy (IMRT) (5). Total dose was 70 Gy in 25 patients, 76 Gy in 2 patients and 66 Gy in 1 patient. Squamous cell carcinoma was the most common histology (68%). Primary tumor was clinical stage T1 in 6 (21%), T2 in 7 (25%), T3 in 3 (11%), T4a in 5 (8%) and T4b in 7 (25%) patients. Nodal stage was N0 in 24, N1 in 2, N2 in 1, and N3 in 1 patients. Most patients (93%) received concurrent chemotherapy with cisplatin (19) or carboplatin/paclitaxel (7) and 11 (39%) received induction chemotherapy. Median follow up was 39 months (range: 5-104 months). The 2- and 5- year LR was 9% (CI 95: 1%-25%) and 14% (CI 95: 3%-32%), respectively. The 2- and 5- year RhFS were 87% (CI 95: 74%-100%) and 74% (CI 95: 57%-98%), respectively. 5-year OS was 86% (CI 95: 72%-100%). Outcomes for patients offered rhinectomy are listed in Table 1. Out of the 3 patients that recurred locally, 2 underwent salvage total rhinectomy, and 1 proceeded with immunotherapy. Among these 3 local recurrences, one patient only received 66 Gy without chemotherapy as no gross tumor was visible after excisional biopsy. The late effect of nasal or lacrimal obstruction which required operative intervention occurred in 10 (35%) of patients.
Conclusion: Non-operative management utilizing proton RT results in excellent local control for the treatment of nasal cavity cancers. This approach appears to be an effective option for patients who wish to avoid partial or total rhinectomy or who have unresectable disease.

Abstract 3689 – Table 1: Patients offered rhinectomy (n=17)
	2-year (CI 95)	5-year (CI 95)
OS	100% (100%-100%)	91% (75%-100%)
RhFS	93% (80%-100%)	84% (65%-100%)
LR	7.1% (0.4%-28%)	7.1% (0.4%-28%)