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.