2805 - Non-Operative Management of Nasal Cavity Cancers with Definitive Proton Beam Therapy or Intensity Modulated Radiation Therapy for Organ Preservation

Purpose/Objective(s): Management of nasal cavity (NC) cancers historically includes surgery and adjuvant therapy. Resection of anterior tumors entails partial or total rhinectomy and locally extensive tumors may be unresectable at diagnosis. With the goal of avoiding potential negative impacts of surgery on cosmesis and quality of life, our institution implemented use of definitive radiotherapy (RT) with proton beam therapy (PBT) and intensity modulated RT (IMRT), with or without chemotherapy (CMT), for non-operative management of NC cancers.

Materials/Methods: All patients (pts) with NC cancers at our institution that received definitive RT with or without CMT were included. Pts who underwent oncologic resection, tumors originating from the paranasal sinuses or nasopharynx, and esthesioneuroblastoma were excluded. The primary endpoint was cumulative incidence of local recurrence in the NC (LR) measured from treatment start date with death as a competing risk. Additional endpoints included progression free survival (PFS), overall survival (OS), and grade 3+ toxicity, and methods included Kaplan-Meier and univariable Cox regression (UVA).

Results: Since 2002, 44 pts were identified, of which 29 received PBT (entire course or boost) and 15 received IMRT alone. Pathology was squamous cell carcinoma in 35 (80%) pts and clinical T-stages included T1-T2 (48%), T3 (9%), T4a (23%), and T4b (20%). Six (14%) pts were N+ and 14 (32%) had unresectable disease. All but 3 pts completed the full planned RT course, 35 (80%) received concurrent CMT (cisplatin [23] and carboplatin [12] based), and 15 (34%) received induction CMT. Total RT dose was 70 Gy or greater in 86% of pts. Median follow up was 50 months (95% CI 34, 83). For the entire cohort, 2-year LR was 12% (95% CI 4.4%, 25%), 5-year LR was 16% (95% CI 6.2%, 30%), and median PFS was 80 months (95% CI 58, -). Table 1 shows 2-year outcomes comparing PBT to IMRT. On UVA, hazard ratio (HR) was 0.38 for PBT compared to IMRT (p=0.2) for LR and 0.49 (p=0.2) for PFS. Unresectable disease (HR 2.95, p=0.04), completion of RT course (HR 0.27, p=0.05), and total dose > 70 Gy (HR 0.28, p=0.03) were significant on UVA for PFS but not for LR. Six pts developed local recurrence, of which 1 underwent rhinectomy, 1 re-irradiation then rhinectomy, and 4 received salvage immunotherapy. Acute grade 3+ dermatitis or mucositis occurred in 2 pts. In 12 pts, a surgical procedure for late nasal toxicity was performed, primarily for nasolacrimal obstruction.

Conclusion: Definitive RT with or without CMT demonstrates efficacy for definitive treatment of NC cancers. With use of salvage immunotherapy, the rate of rhinectomy is rare. This strategy provides an option of organ preservation for patients choosing to avoid rhinectomy in the upfront treatment for nasal cavity cancers.