1058 - Similar Overall Survival in Oropharyngeal Cancer Patients Treated with IMRT vs. Proton Therapy
Presenter(s)
Y. Wu1, E. C. Dee2, N. Riaz2, S. Choi3, N. Chadha4, A. Elkhadrawy4, D. Ratnikov5, J. Suggitt6, J. Fukuda7, A. Shamseddine2, S. M. McBride2, D. Y. Gelblum2, Y. Yu2, J. J. Kang8, C. M. Wong9, E. Sherman10, W. Wong10, L. Dunn1, A. Ho1, and N. Y. Lee2; 1Memorial Sloan Kettering Cancer Center, New York, NY, 2Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, 3Case Western Reserve University School of Medicine, Cleveland, OH, 4Weill Cornell Medical College, New York, NY, 5Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 6NYU Grossman School of Medicine, New York, NY, 7Northeastern University, Boston, MA, 8Memorial Sloan Kettering Cancer Center, New Haven, CT, 9Yale University, New Haven, CT, 10Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
Purpose/Objective(s):
IMRT is standard of care for locally advanced oropharyngeal squamous cell carcinoma (OPSCC) but is associated with substantial toxicities. Proton therapy is thought to have similar efficacy but may reduce toxicity. Recent conflicting phase III suggests proton therapy may have superior OS to IMRT in OPSCC. While additional phase 3 data mature, we sought to leverage single institution data at a high-volume center to compare the oncologic outcomes of IMRT versus proton CRT.Materials/Methods:
From 1/2019 to 12/2023, consecutive patients with OPSCC who underwent chemoRT with curative intent with either IMRT or proton therapy were included. Patients’ demographic and clinical variables were collected. Outcomes included overall survival (OS), progression- free survival (PFS), distant metastasis- free survival (DMFS) and locoregional failure (LRF). OS, PFS, and DMFS were modeled using Kaplan-Meier method, adjusting for T-stage, N-stage, sex, age at diagnosis, smoking history, cisplatin vs non-cisplatin chemotherapy, HPV status and p16 status. Locoregional failure (LRF) was compared using Fine-Gray method with death and distant metastasis as competing events. Data lock occurred on 12/31/2025.Results:
Out of the entire cohort of 559 OPSCC, 452 (80.9%) received IMRT and 107 (19.1%) received proton therapy, all with concurrent chemotherapy. T- stage and N- stage distributions were similar between the two cohorts, p=0.073 for T- stage and p= 0.895 for N- stage (See Table). At a median follow- up time of 54.0 months (range 0.52-83.31 months), the 5-year OS was 82.5% (95%CI 66.0%-91.5%) for proton versus 85.8% (81.8%-89.0%) for IMRT (unadjusted HR 0.89, 95%CI 0.47-1.70, p=0.72). Multivariable modeling was conducted adjusting for T- stage, N- stage, sex, age at diagnosis, smoking history, cisplatin vs non- cisplatin chemotherapy, HPV status and p16 status; adjusted HR 1.08, 95% CI 0.55-2.11, p=0.82. The 5-year PFS was 77.8% (95%CI 67.5%-85.2%) for proton versus 78.2% (73.8%-82.0%) for IMRT (unadjusted HR 0.98, 95%CI 0.61-1.57, p=0.92; adjusted HR 1.08, 95% CI 0.66- 1.76, p=0.76). Adjusted analysis for 5- year DMFS (Cox modeling) and LRF (Fine-Gray modeling) showed similar results for proton versus IMRT (DMFS 80.6% vs 80.0%, p=0.94; LRF rate 5.97% vs 4.65%, p=0.48).Conclusion: In a large consecutive cohort of OPSCC treated at a single high-volume institution, we found no difference in OS, PFS, DMFS, and LRF in OPSCC patients treated with either proton or IMRT. We believe both modalities are equally effective in curing these tumors in the setting of concurrent chemotherapy.
| proton | IMRT | ||
| T stage (AJCC 7th) | P=0.073 | ||
| T0-2 | 49.53% | 59.07% | |
| T3-4 | 50.47% | 40.93% | |
| N stage (AJCC 7th) | P=0.895 | ||
| N0-1 | 18.69% | 18.14% | |
| N2-3 | 81.31% | 81.86% |