Propensity score matching analysis of cisplatin-based concurrent chemotherapy in low risk nasopharyngeal carcinoma in the intensity-modulated radiotherapy era

BACKGROUND: Patients with stage II nasopharyngeal carcinoma were reported to benefit from adding cisplatin-based concurrent chemotherapy to two-dimensional conventional radiotherapy. But this benefit becomes uncertain in the intensity-modulated radiotherapy (IMRT) era, owing to its significant advantage. METHODS: We enrolled 661 low risk (T1N1M0, T2N0-1M0 or T3N0M0, the 2010 UICC/AJCC staging system) patients who underwent IMRT with or without concurrent chemotherapy. Particularly, patients with IMRT alone or IMRT plus cisplatin-based concurrent chemotherapy were equally matched using propensity-score matching method. Overall survival (OS), distant metastasis-free survival (DMFS) and locoregional relapse-free survival (LRFS) were assessed with Kaplan-Meier method, log-rank test and Cox regression. RESULTS: Among 661 patients, IMRT alone achieved parallel OS (P = 0.379), DMFS (P = 0.169) and LRFS (P = 0.849) to IMRT plus concurrent chemotherapy. In the propensity-matched cohort of 482 patients, similar survival were observed between both arms (4-years OS 97.4% vs 96.1%, P = 0.134; DMFS 96.5% vs 95.1%, P = 0.763; LRFS 93.8% vs 91.5%, P = 0.715). In multivariate analysis, cisplatin-based concurrent chemotherapy did not lower the risk of death, distant metastasis or locoregional relapse. And this association remained unchanged in subgroups by age, sex, histology and stage. CONCLUSIONS: In this study, low risk nasopharyngeal carcinoma patients who underwent IMRT could not benefit from cisplatin-based concurrent chemotherapy.