The impact of the cumulative dose of cisplatin during concurrent chemoradiotherapy on the clinical outcomes of patients with advanced-stage nasopharyngeal carcinoma in an era of intensity-modulated radiotherapy.

ABSTRACT

BACKGROUND: The impact of cumulative dose of cisplatin on clinical outcomes of nasopharyngeal carcinoma (NPC) patients who received intensity-modulated radiotherapy (IMRT) was evaluated. METHODS: This study included 491 consecutive patients with histologically confirmed NPC who were treated with concurrent chemoradiotherapy with IMRT. The patients were divided into three groups low- (cumulative dose≤100 mg/m2), medium- (cumulative dose>100 mg/m2 and ≤200 mg/m2), and high- (cumulative dose>200 mg/m2) dose groups. Subgroups of patients included pre-treatment levels of Epstein-Barr Virus DNA (EBV DNA)<4000 copies/ml and pre-treatment EBV DNA≥4000 copies/ml. To test for independent significance, the Kaplan-Meier with the log-rank test and the Cox proportional hazards model were used. RESULTS: The 5-year overall survival (OS) rates of the low-, medium-, and high-dose groups were 64.1%, 91.1%, and 89.4%, respectively (P=0.002). Based on multivariate analysis, patients who were in the medium- and high-dose groups had compared with the low-dose group, with an odds ratio of 0.135 (95% CI 0.045-0.405, P<0.001) and 0.225 (95% CI 0.069-0.734, P=0.013), respectively. For the low-risk patients, the cumulative dose of cisplatin significantly associated with a lower OS (P<0.001). The medium-dose group had reduced odds of death compared with the low-dose group, with an odds ratio of 0.062 (95% CI 0.001-0.347, P=0.002), according to multivariate analysis. CONCLUSIONS: The cumulative dose of cisplatin is associated with OS and distant metastasis-free survival (DMFS) among NPC patients who received IMRT.