The Role of Adjuvant Chemotherapy After Definitive Chemoradiation Therapy in Locoregionally Advanced Nasopharyngeal Carcinoma in a Non-endemic Area: Multi-institutional Retrospective Study Using Propensity Score Matching Analysis

Abstract

It is unclear whether adjuvant chemotherapy (AC) provides an additional survival benefit over concurrent chemoradiation therapy (CCRT) in locoregionally advanced nasopharyngeal carcinoma (NPC). Thus, we evaluated the role of AC after definitive CCRT. We undertook a multicenter retrospective study at 15 institutions. Seven hundred and seven patients of nasopharynx cancer staged T3-4 or N1-3 were collected. They received cisplatin-based CCRT alone or followed by AC consisting of cisplatin and fluorouracil. There were 380 patients in the no AC arm and 327 patients in the AC arm. Patients in both treatment arms were matched using the propensity score matching method, and then the clinical outcomes and toxicities were analyzed in finally matched 478 patients. At a median follow-up time of 46 months, the AC arm did not show higher overall survival (OS) (86% versus 80%, P =.0894) at 3 years. However, the AC arm had a significantly higher failure-free survival (FFS) rate at 3 years than the no AC arm (75% vs 66%, P = 0.018). AC was a significant factor for FFS on the multivariate analysis (P = .046; HR = 0.77; 95% CI 0.55-0.98). The AC arm did not achieve a significantly higher locoregional FFS rate at 3 years than the no AC arm (91% vs 84%, P = .1115). However, the 3-year distant FFS rate in the AC arm was significantly higher than no AC arm (83% vs 78%, P =.0427). AC after definitive CCRT significantly improved FFS, however, which was not translated into the improvement of OS for the patients with locoregionally advanced NPC in a non-endemic region. The observed effect of AC was mainly attributed to the improved distant control, not locoregional control.