Optimal cumulative cisplatin dose in nasopharyngeal carcinoma patients receiving additional induction chemotherapy

To clarify the optimal cumulative cisplatin dose (CCD) in locoregionally-advanced nasopharyngel carcinoma (NPC) patients receiving induction chemotherapy (IC) plus concurrent chemoradiotherapy (CCRT). Using the NPC-specific database from the established big-data intelligence platform at Sun Yat-Sen University Cancer Center, 583 non-disseminated, locoregionally-advanced NPC patients receiving IC plus CCRT were enrolled. Propensity score matching (PSM) analysis was conducted to control for confounding factors. The median CCD was 160 mg/m² after IC (range, 40-300 mg/m² ); only 74 patients (12.7%) achieved CCD >200 mg/m² . Patients receiving >200 mg/m² CCD did not show significantly improved 5-year overall survival (OS) (HR = 1.19; 95% confidence intervals [CI] 0.69-2.06, P = .53) and progression-free survival (PFS) (HR = 1.03; 95% CI: 0.63-1.68, P = .92) compared with patients receiving <200 mg/m² CCD. Further investigations of the potential of median CCD (160 mg/m² ) to yield survival benefits revealed that there were no significant differences in survival endpoints between patients receiving CCD >160 mg/m² and CCD < 160 mg/m² in both the original and PSM cohorts. In addition, subgroup analysis indicated a favorable PFS, but not OS, with higher cisplatin administration in patients with pretreatment Epstein-Barr virus deoxyribonucleic acid (EBV DNA) <1000 copies/mL (HR = 0.26, 95% CI: 0.07-0.93, P = .03) and receiving <3 IC cycles (HR = 0.59, 95% CI 0.33-1.07, P = .08). Our analysis of real world data provided references for the optimal CCD in locoregionally-advanced NPC receiving additional IC. The causal relationship between 200 mg/m² CCD and improved survival was not defined; 160 mg/m² CCD might be enough. However, for patients with EBV DNA <1000 copy/mL and receiving <3 IC cycles, a higher dose might be necessary.