A higher number of chemotherapy cycles given during and after radiation is linked to increased rates of radiation-induced trismus in locally advanced nasopharyngeal cancer patients

Abstract

Aim: To investigate the impact of the number of chemotherapy cycles (NCTC) on the occurrence of radiation-induced trismus (RIT) in locally advanced nasopharyngeal cancer (LA-NPC) patients who underwent definitive concurrent chemoradiotherapy (CCRT) followed by consolidation chemotherapy. Materials and methods: A retrospective analysis was conducted on LA-NPC patients who underwent CCRT between July 2011 and March 2024. The cohort was categorized based on the NCTC (< 3 vs. ≥ 3) and total NCTC (TNCTC: < 4 vs. ≥ 4). The primary objective of this study was to investigate the correlation between the RIT [a maximum mouth opening (MMO) of ≤ 35 mm] incidence and the NCTC and TNCTC parameters. Results: A total of 293 patients were included in the study. The incidence of RIT was significantly higher in patients receiving NCTC ≥ 3 (32.5% vs.16.9%; P < 0.001) and TNCTC ≥ 4 (32.4% vs.15.0; P < 0.001). Univariate analysis identified NCTC ≥ 3 (P < 0.001), TNCTC ≥ 4 (P < 0.001), smoking history (P = 0.03), pre-treatment MMO < 41 mm (P = 0.003), and advanced tumor stage (T3-4) (P < 0.001) as independent predictors of RIT. Multivariate analysis revealed that all factors were independent and significant predictors of RIT in this patient group (P < 0.05 for each). Conclusion: The findings of this retrospective study indicate that higher NCTC and TNCTC are independently correlated with an increased risk of RIT in LA-NPC patients undergoing CCRT.