2772 - A Multicenter Study Comparing Survival Outcomes of IMRT and Non-IMRT Techniques in Non-Metastatic Nasopharyngeal Cancer Using Propensity Score Matching
Presenter(s)
C. Jiarpinitnun1, A. Prayongrat2, K. Jeerapradit3, R. Jiratrachu4, A. Dechaphunkul5, C. Vinayanuwattikun6, P. Danchaivijitr7, T. Dechaphunkul8, P. Pattaranutaporn1, N. Ngamphaiboon3, and J. Setakornnukul9; 1Division of Radiation Oncology, Department of Radiology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, 2Division of Radiation Oncology, Department of Radiation, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Bangkok, Thailand, 3Division of Medical Oncology, Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, 4Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Prince of Songkla University, Songkla, Thailand, 5Unit of Medical Oncology, Department of Internal Medicine, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand, 6Division of Medical Oncology, Department of Medicine, Faculty of medicine, Chulalongkorn university, Bangkok, Thailand, 7Division of Medical Oncology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, 8Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medicine, Prince of Songkla University, Songkla, Thailand, 9Division of Radiation Oncology, Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
Purpose/Objective(s): This study aimed to assess the survival benefits of intensity-modulated radiation therapy (IMRT) compared with non-IMRT techniques for curative treatment in non-metastatic nasopharyngeal carcinoma (NPC) in real-world clinical settings
Materials/Methods: Non-metastatic NPC patients who underwent curative treatment at four academic cancer centers in Thailand between 2008 and 2020 were included. Propensity score matching was applied to balance factors such as age, gender, performance status, staging, and type of chemotherapy. Survival outcomes were compared between patients treated with IMRT and those treated with non-IMRT techniques. A p-value of < 0.05 was considered statistically significant. The subgroup analysis was preplanned based on tumor staging, comparing early stage versus locally advanced stage disease.
Results: A total of 1,669 non-metastatic NPC patients were treated with either IMRT (1,214 patients) or non-IMRT (455 patients). After 1:1 propensity score matching, 319 patients were included in each group, for a total of 638 patients. Most patients were male (70%) and presented with stage III-IVb disease (80%). Treatment included radiation therapy (RT) alone (11%), chemoradiotherapy (CRT) alone (8%), and induction or adjuvant chemotherapy followed by CRT (81%). Cisplatin was the most common chemotherapy used during CRT (89%). Most of baseline characteristics and treatments were well balanced, except for -the cumulative dose of cisplatin during CRT = 200 mg/m² (p<0.01), which were more prominent in the non-IMRT group. RT interruption rates were similar between the two groups (2.7% for IMRT vs. 2.3% for non-IMRT; p=0.9). The median follow-up time was 64 months. Patients treated with IMRT had significantly better overall survival (OS) compared to those treated with non-IMRT (HR=0.55; 95% CI, 0.43–0.70; p<0.01). The survival benefit of IMRT was also observed in disease-free survival (DFS) (HR=0.60; 95% CI, 0.48–0.75; p<0.01) and locoregional recurrence-free survival (LRFS) (HR=0.57; 95% CI, 0.45–0.71; p<0.01). For subgroup analysis, stage III-IVb patients, IMRT significantly improved OS, DFS, and LRFS (all p<0.01), while no survival benefit was observed in stage I-II (OS p=0.66; DFS p=0.70; LRFS p=0.53) with p-interaction 0.033.
Conclusion: This real-world, multicenter study using propensity score matching demonstrates that IMRT significantly improves survival outcomes, particularly in locally advanced NPC, while showing no significant benefit in early-stage disease. However, further prospective studies are needed to confirm these results.