Prognostic value of wait time in nasopharyngeal carcinoma treated with intensity modulated radiotherapy: a propensitymatched analysis

Abstract

// Yu-Pei Chen 1, * , Yan-Ping Mao 1, * , Wen-Na Zhang 1, * , Lei Chen 1 , Ling-Long Tang 1 , Wen-Fei Li 1 , Xu Liu 1 , Guan-Qun Zhou 1 , Rui Guo 1 , Ying Sun 1 , Tie-Bang Kang 1 , Mu-Sheng Zeng 1 , Jun Ma 1 1 Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, People’s Republic of China * These authors contributed equally to this work Correspondence to: Jun Ma, e-mail: majun2@mail.sysu.edu.cn Keywords: nasopharyngeal carcinoma, wait time, intensity modulated radiotherapy, prognosis, propensity score matching Received: October 08, 2015      Accepted: January 29, 2016      Published: February 29, 2016 ABSTRACT The aim of this study was to determine the prognostic value of wait time from histological diagnosis to primary treatmen for nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT). Between October 2009 and February 2012, a total of 1672 NPC patients were retrospectively analyzed. A cutoff value of > 4 weeks was used to define prolonged wait time. Matched patients according to the wait time were identified using propensity score matching (PSM), which was also used to identify matched patients for subsequent stratified analyses. Differences in progression-free survival (PFS), overall survival (OS), distant metastasis-free survival (DMFS), and locoregional relapse-free survival (LRFS) were estimated using the Kaplan–Meier method and Cox proportional hazards models. In total, 407 pairs of NPC patients were selected by PSM. The 3-year PFS rate was significantly lower for patients with a prolonged wait time (> 4 weeks) than for those with an acceptable wait time ( P = 0.035). Stratified analyses revealed that the negative effects of a prolonged wait time occurred primarily in patients with advanced NPC without neoadjuvant chemotherapy (NACT; PFS: P = 0.040; DMFS: P = 0.028). In multivariate analysis, a prolonged wait time was found to be an independent unfavorable prognostic factor for PFS and DMFS in advanced-staged patients without NACT. These results suggest that a prolonged time (> 4 weeks) between diagnosis and primary radical radiotherapy is a disadvantage for NPC patients, particularly those with advanced disease receiving no NACT. Thus, it is necessary to optimize resources for decreasing this wait time, although additional studies are warranted to further clarify our findings.