Long-Term Therapeutic Outcome and Prognostic Factors for Patients with Nasopharyngeal Carcinoma Receiving Intensity-Modulated Radiation Therapy: An Analysis of 608 Patients from Low-Endemic Regions of China

Abstract

This study aimed at evaluating the long-term outcome and prognostic factors of patients with nasopharyngeal carcinoma (NPC) from low-endemic regions of China who received definitive intensity-modulated radiotherapy (IMRT). Clinical data from 608 patients with newly-diagnosed non-metastatic NPC who have received initial treatment at our cancer center from January, 2008 to December, 2013 were retrospectively reviewed. All patients received definitive IMRT, and 87.7% received platinum-based chemotherapy. Survival data were analyzed by Kaplan-Meier method, and Log-rank test and Cox regression analyses were performed to determine the prognostic factors. The median follow-up duration was 51 months (follow-up rate, 98.5%; range, 10-106 months) for the entire cohort. The 5-year overall survival (OS) rate was 79.6%. The 5-year local relapse-free survival rate (LRFS), region relapse-free survival rate (RRFS), distant metastasis-free survival rate (DMFS) and progression-free survival rate (PFS) were 92.4%, 93.4%, 79.2% and 74.2%, respectively. A total of 153 patients have experienced treatment failure, with distant metastasis as the primary cause in 77.1% (118/153). Patients with T4 or N3 diseases had much poorer prognosis than other subcategories. The 5-year OS rates for patients with T1-T4 diseases were 87.9%, 82.1%, 83.3% and 69.2%, respectively. The 5-year OS rates for patients with N1-N3 were Stage T4 and N3 were closely associated with distant metastasis, with metastatic rate of 29.2% and 45.5%, respectively. Multivariate analysis revealed that prognosis was primarily influenced by T stage, N stage and clinical stage, with N stage and T stage acting as the independent prognostic factor for OS, PFS, RRFS and DMFS, and clinical stage for OS, PFS, LRFS and DMFS. IMRT provides patients with non-metastatic NPC with satisfactory long-term survival. T stage, N stage and clinical stage are important prognostic factors for NPC patients. Patients with T4 or N3 diseases have significantly increased distant metastatic rates and poor survival.