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

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/m(2)), medium- (cumulative dose >100 mg/m(2) and ≤200 mg/m(2)), and high- (cumulative dose >200 mg/m(2)) 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. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12885-015-1964-8) contains supplementary material, which is available to authorized users.