ESTRO 2025 - Abstract Book

S929

Clinical – Head & neck

ESTRO 2025

at 75 mg/m² and cisplatin at 75 mg/m² chemotherapy, followed by cisplatin-based CCRT. The LDFRT group received additional radiation to the involved lymph nodes at 50 cGy twice daily for 2 days during each cycle of IC. The primary endpoint was to assess the objective response rate (ORR) after induction chemotherapy, while secondary endpoints included 2-year overall survival (OS) and progression-free survival (PFS). Tumor volumes of the nasopharynx and lymph nodes were recorded before and after IC to calculate the tumor regression rates. Efficacy was assessed using intent-to-treat (ITT) analysis .

Results:

From May 2020 to June 2022, 84 patients were enrolled, and 82 eligible patients (41 each) were included in the ITT analysis. After IC, the overall ORR was higher in the LDFRT group than in the control group (100% vs. 85.37%, p =0.03). The regression rate and ORR of lymph nodes were improved in the LDFRT group compared to the control group (91.52% vs. 53.91%, p<0.001; 100% vs. 82.93%, p =0.001, respectively). However, there was no significant difference in the regression rate and ORR of nasopharyngeal lesions (60.68% vs 55.19%, p =0.12; 92.68% vs 87.80%, p =0.71,respectively). The complete response (CR) rate of lymph nodes in the LDFRT group was 46.34%, surpassing the 26.83% in the control group,with borderline significance (p=0.06). After a median follow-up of 30 months, the 2-year OS rates were 100% in both groups. There was a trend toward improved PFS and distant metastasis-free survival in the LDFRT group (87.59% vs. 74.63%, p =0.15; 90.34% vs. 79.87%, p =0.28, respectively). There was no difference in acute toxicity. Conclusion: LDFRT has the potential to serve as a sensitizer for induction chemotherapy, offering a promising treatment option for high-risk LANPC patients.

Keywords: Low-dose radiotherapy,nasopharynx,induction

References: [1]Arnold, SM, Kudrimoti, M, Dressler, EV, et al. Using low-dose radiation to potentiate the effect of induction chemotherapy in head and neck cancer: Results of a prospective phase 2 trial. Adv Radiat Oncol. 2016; 1 (4): 252 259.