S581
Clinical – Head & neck
ESTRO 2026
Material/Methods: From March 2018 to December 2022, a prospective multicenter clinical trial (ChiCTR-OIC-17013579) initiated by Zhang Peng's team at Sichuan Cancer Hospital,China evaluated the efficacy and adverse effects of pulse low-dose-rate intensity-modulated radiotherapy (PLDR-IMRT) based on IMRT for local reirradiation in patients with recurrent nasopharyngeal carcinoma. Results: The study enrolled 52 patients, all of whom received PLDR-IMRT in combination with systemic therapy. The median dose administered was 60Gy(50.4-70 Gy/28- 35f). Upon analyzing the five-year follow-up data from March 2018 to December 2022, which includes 14 patients treated after January 2020 (during the 2019-nCoV epidemic control period), the median follow-up time for all patients was found to be 68 months. For those treated during the COVID-19 control period, the median follow-up time was 44 months, whereas for the other patients, it was 73 months. The overall objective response rate (ORR) was 91.6%. The overall cohort exhibited a median overall survival (OS) of 52 months and a median progression-free survival (PFS) of 29 months. Among patients not under COVID-19 control, the median OS had not been reached, with a median PFS of 64 months. In contrast, patients treated during the COVID-19 control period displayed a median OS of 15 months and a median PFS of 11 months. Survival analysis revealed statistically significant differences in median OS (p=0.0098) and median PFS (p=0.003) around January 2020 (before and after COVID-19 control). The 1-year, 2-year, 3-year, and 4-year OS rates for the overall cohort were 88.24%, 73.53%, 64.71%, and 55.88%, respectively. For patients not under COVID-19 control, the corresponding rates were 95%, 85%, 80%, 70%, and 50% for 1-year, 2-year, 3- year, 4-year, and 5-year OS, respectively. The 1-year, 2- year, 3-year, 4-year, and 5-year PFS rates were 90%, 80%, 65%, 55%, and 45%. The incidence of PLDR acute serious adverse events (SAE) (grade 3+) was 22.2%, while the incidence of chronic SAEs was approximately 19.4%. Conclusion: The combination of PLDR-IMRT and systemic therapy is a safe and effective re-irradiation regimen for treating locally recurrent nasopharyngeal carcinoma. References: [1]Blanchard P, Lee A, Marguet S, et al. Chemotherapy and radiotherapy in nasopharyngeal carcinoma: an update of the MAC-NPC etaanalysis. Lancet Oncol. 2015;16(6):645-655.[2]Zhang P, Wang B, et al. Local tumor control and Normal tissue toxicity of pulsed low-dose-rate radiation therapy (PLRT) for recurrent lung cancer: an In vivo study. Int J Radiat Oncol Biol
fractionations ranged from 30 to 50Gy in 5 fractions and 30 to 54Gy in 3 fractions. For high dose palliative RT, doses ranged from 50 to 71Gy EQD2 (alpha/beta=10). 10 patients had de novo metastatic disease, 14 had metachronous oligorecurrence and 4 had oligoprogressive disease. Local and distant failure rates were 10.7% and 57.1%. All cases of local failure occurred in the metachronous oligorecurrence group. Overall median PFS was 36.9 months and OS 84.4 months. 5 year OS was 75%. For de novo metastatic disease, median PFS was 8.5 months and 5 year OS 70%. For metachronous oligorecurrence, median PFS was 44.8 months and 5 year OS 85.7%. For oligoprogressive disease, median PFS was 53.2 months and 5 year OS 50%. Conclusion: Treatment with systemic chemotherapy and MDT yielded encouraging results in terms of long term disease control and overall survival in our cohort of oligometastatic NPC patients, with metachronous oligorecurrence having the most favourable survival outcomes. However, distant failure rates remain significant. Further large scale prospective, randomised trials on combining MDT with now standard, intensified chemoimmunotherapy regimens are eagerly awaited to further inform practice in this population. Keywords: oligometastases, nasopharyngeal cancer Efficacy and safety of PLDR for the re-irradiation of recurrent NPC, a prospective, multicenter,phase II clinical trial.(ChiCTR-OIC-17013579) Rui Huang 1 , Peng Zhang 1 , Zhihui Li 2 , Fan Yang 3 , Yu Zhang 4 1 Department of Radiation Oncology, Sichuan Clinical Research Center for Cancer, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, Affiliated Cancer Hospital of University of Electronic Science and Technology of China, Chengdu, China. 2 Department of Oncology, The General Hospital of Western Theater Command, Chengdu, China. 3 Department of Oncology, Xinqiao Hospital, Army Medical University, Chongqing, China. 4 Department of Oncology, MianYang Central Hospital, Mianyang, China Purpose/Objective: Recurrence is the major failure pattern among patients with nasopharyngeal carcinoma who have undergone radical treatment. When reirradiation of the recurrent lesion is required, exploring a new approach is key to improving survival benefits while enhancing efficacy and reducing severe adverse reactions. Digital Poster 1992
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