244 - Proton vs. Photon for Nasopharyngeal Carcinoma: Toxicity and Survival in a Phase 2 Randomized Study
Presenter(s)
L. Kong1,2, J. Hu3, Q. Huang3, W. Hu3, J. Gao3, and H. Zhang4; 1Shanghai Proton and Heavy Ion Center (SPHIC), Shanghai, China, 2Fudan University Shanghai Cancer Center, Shanghai, China, 3Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Shanghai, China, 4Shanghai proton and heavy-ion center, shanghai, China
Purpose/Objective(s): Nasopharyngeal carcinoma is endemic in China. Use of Intensity-modulated radiation therapy (IMRT) and development in comprehensive treatment strategy has significantly improved the prognosis of this disease. To reduce the toxicities associated to treatment is of great interest, especially in long-term survivors. Particle therapy (such as proton radiation therapy, and carbon ion radiation therapy [CIRT]) could significantly spare the dose to the surrounding critical organs, thus, yielding an improved toxicity profile without compromising disease control. Here, we report the outcome of our phase 2 randomized trial.
Materials/Methods: This is a phase 2 randomized study comparing the efficacy and toxicity profiles of intensity-modulated radiation therapy (IMRT) combined with CIRT and intensity-modulated proton radiation therapy (IMPT) combined with CIRT. Patients were randomized at 1:1 ratio to each group. The primary endpoint of the study was the prevalence of Grade 2 or above xerostomia observed at 6 months after completion of radiation therapy. The dose of IMRT or IMPT was 56 GyRBE in 28 fractions. CIRT was delivered as a boost with a dose of 17.5 Gy in 5 fractions. Induction chemotherapy and concurrent chemotherapy was prescribed at the discretion of the attending physician. Toxicities were assessed using CTCAE v4.03.
Results: A total of 136 patients were enrolled (68 in the IMRT+CIRT group, and 68 in the IMPT+CIRT group). The median follow-up of the whole cohort was 51.5 months (IQR 47.1-57.9). The prevalence of Grade 2 or above xerostomia at 6 months after completion of radiation therapy was 27% and 16% (p=0.13) in the IMRT+CIRT group and IMPT+CIRT group, respectively. The 3-year overall survival was 100% (95% CI 100-100) in the IMRT+CIRT group versus 98.5% (95% CI 95.5-100) in the IMPT+CIRT group (log-rank p=0.99). And the 3-year progression-free survival was 90.8% (95% CI 84.0-98.1) in the IMRT+CIRT group and 88.1% (95% CI 80.6-96.2) in the IMPT+CIRT group (log-rank p=0.64).
Conclusion: IMPT plus CIRT could improve the xerostomia at 6 months after completion of radiation therapy. No significant difference in overall survival and progression-free survival was observed. (NCT04528394)