ESTRO 2025 - Abstract Book

S939

Clinical – Head & neck

ESTRO 2025

1 Radiotherapy and oncology, Habib Bourguiba Hospital, Sfax, Tunisia. 2 Medical Oncology, Habib Bourguiba Hospital, Sfax, Tunisia

Purpose/Objective: Adding induction chemotherapy (IC) to concomitant chemo-radiotherapy (CCR) is the standard of care for locally advanced nasopharyngeal carcinoma (NPC) [1]. Taxanes-cisplatin-5fluoro-uracil (TPF) and gemcitabine-cisplatin (GP) induction regimens are the most used and both proved through randomized trials that they improve outcomes [2-3]. Chen et al reported a mean volume reduction of 28-33% with GP versus 61.4-68% with TPF, but these regimens have not been compared prospectively [4]. This study aimed to evaluate the impact of chemotherapy type and doses on outcomes of NPC. Material/Methods: We retrospectively reviewed the data of patients with locally advanced non-metastatic stage II-IVA NPC treated between October 2016 and October 2022 with IC followed by CCR with intensity-modulated radiotherapy (IMRT) and weekly cisplatin (40 mg/m²). IMRT was delivered with an integrated simultaneous boost of 33 fractions at a total dose of 69.96 Gy, considering response to IC. Survival analysis for overall survival (OS), loco-regional free survival (LRFS), metastatic-free survival (MFS), and disease-free survival (DFS) was performed according to Kaplan-Meier method. Log rank test was used to compare prognostic factors. Results: We included 149 patients. Disease was classified as stage III-IVA in 86% of cases. Patients received 3 IC courses in 96% of cases. It was TPF IC in 114 cases (76%), GP in 22 cases (15%) and other protocols in 13 cases (9%). Grade 3-4 IC related acute toxicity was noted in 31% of cases with TPF versus 21% with GP. After a median follow-up of 62 months [27-96], we noted 21 loco-regional (14%) and 35 distant relapses (23.5%). Five year-OS, LRFS, MFS and DFS were respectively 78%, 83.4%, 75.5% and 66.6%.

In subgroup analysis, the loco-regional relapse rate was 12.2% in patients receiving TFP IC versus 36.8% in those receiving GP IC. GP IC significantly reduced LRFS at 5 years (85.5% versus 59.6%; p=0.03) but did not significantly affect other survivals. Receiving 4 or more cisplatin concomitant courses was associated with a better DFS (71% vs 57.3%; p=0.035). A total cisplatin cumulative dose of at least 380 mg/m² was associated with better OS (p=0.001), LRFS (p=0.011), MFS (p=0.005) and DFS (p=0.001). No grade 3-4 late side effects were reported.