Individual and Cumulative Impacts of Diagnosis‐to‐Treatment Interval and Radiotherapy Interval on Survival in Nasopharyngeal Cancer
Erkan Topkan, Efsun Somay, Sibel Bascil, Duriye Ozturk, Ugur SelekAbstract
Objective
To evaluate the impact of diagnosis‐to‐treatment interval (DTI) and radiotherapy interval (RTI) on overall survival (OS) in locally advanced nasopharyngeal carcinoma (LA‐NPC) treated with concurrent chemoradiotherapy (CCRT).
Study Design
Retrospective database study.
Settings
Single tertiary academic center.
Methods
We analyzed 285 LA‐NPC patients treated with CCRT between 2010 and 2024. Receiver operating characteristic (ROC) analysis was used to derive optimal thresholds for DTI and RTI. OS was estimated using the Kaplan‐Meier method and compared with log‐rank tests. Multivariable Cox models assessed independent associations, with hazard ratios (HRs) reported with 95% confidence intervals (CIs).
Results
After a median follow‐up of 75.6 months, median OS was 108 months. ROC‐derived thresholds of 30 days for DTI and 49 days for RTI were applied. DTI ≤ 30 days was associated with improved OS compared with >30 days (not reached vs 64.0 months; P < .001), as was RTI ≤ 49 versus >49 days (122.0 vs 74.0 months; P < .001). On multivariable analysis, DTI > 30 days (HR: 2.56, 95% CI: [2.11‐3.82], P < .001) and RTI > 49 days (HR: 1.65, 95% CI: 1.09‐2.47, P = .002) were independently associated with inferior OS. Patients with both delays had the poorest survival (median OS: 51.0 months). DTI > 30 days was associated with increased distant metastasis, whereas RTI > 49 days was associated with higher locoregional failure.
Conclusion
DTI > 30 days and RTI > 49 days are independently associated with worse survival in LA‐NPC treated with definitive CCRT. These findings support timely treatment initiation and uninterrupted radiotherapy delivery.