Survival impact of waiting time for radical radiotherapy in nasopharyngeal carcinoma: A large institution-based cohort study from an endemic area.
Whether the waiting time for radical radiotherapy (WRT) detrimentally impacts nasopharyngeal carcinoma (NPC) prognosis is unclear. We estimated the influence of WRT on overall survival (OS) and disease-specific survival (DSS) of NPC.



Patients were identified from prospectively maintained database. WRT was calculated from histological diagnosis to initiation of radiotherapy (RT). Survival analysis was estimated using Weibull parametric model and propensity score analysis (PSA). Recursive partitioning analysis (RPA) identified optimal WRT threshold via conditional inference trees to estimate the greatest survival differences based on randomly selected training and validation sets, and this process was repeated 1000 times to ensure threshold robustness. Sensitivity analysis estimated effects of potential unmeasured confounders.



A total of 9896 patients were included. In multivariate analysis, WRT of 31-60°d, of 61-90°d and of greater than 90°d independently increased mortality risk compared to less than 30°d. Upon RPA, ranges of 30-35°d with the peak of 30°d were confirmed with 89% of simulations validating optimal thresholds. In threshold-based groups, adjusted hazard ratios (HRs) for WRT of greater than 30°d by both Weibull model and PSA were significantly higher than for WRT of less than 30°d [OS: HR = 1.13, 95% confidence interval (CI) 1.04-1.23, P = 0.003; DSS: HR = 1.15, 95% CI 1.05-1.26, P = 0.002]. Sensitivity analysis revealed robustness of results.



WRT independently affects survival. Increasing WRT beyond 30°d was most consistently detrimental to survival. WRT of NPC should be as short as reasonably achievable (ASARA).
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Hu
H
Liang
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Yan-Qun
YQ
Xiang
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Xing
X
Lv
Vidant Medical Center, East Carolina University, Greenville, NC, USA.
Chang-Qing
CQ
Xie
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Epidemiology, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Su-Mei
SM
Cao
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Lin
L
Wang
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Chao-Nan
CN
Qian
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Jing
J
Yang
Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China.
Yan-Fang
YF
Ye
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Medical Information, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Feng
F
Gan
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Liang-Ru
LR
Ke
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Ya-Hui
YH
Yu
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Guo-Ying
GY
Liu
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Wen-Ze
WZ
Qiu
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Xin-Jun
XJ
Huang
Southern China Center for Statistical Science, School of Mathematics, Sun Yat-Sen University, Guangzhou, China.
Can-Hong
CH
Wen
Southern China Center for Statistical Science, School of Mathematics, Sun Yat-Sen University, Guangzhou, China.
Na
N
You
Southern China Center for Statistical Science, School of Mathematics, Sun Yat-Sen University, Guangzhou, China.
Xue-Qin
XQ
Wang
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China. Electronic address: guoxiang@sysucc.org.cn.
Xiang
X
Guo
State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China. Electronic address: xiawx@sysucc.org.cn.
Wei-Xiong
WX
Xia
D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000401:mortality / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D061665:Time-to-Treatment / Q000706:statistics & numerical data*; D014850:Waiting Lists
ASARA; Nasopharyngeal carcinoma; Propensity score analysis; Radical radiotherapy; Recursive partitioning analysis; Sensitivity analysis; Survival; Waiting time; Weibull analysis