Effect of time to initiation of postoperative radiation therapy on survival in surgically managed head and neck cancer

Abstract

BACKGROUND: The objective of this study was to determine the effects of National Comprehensive Cancer Network (NCCN) guideline–adherent initiation of postoperative radiation therapy (PORT) and different time-to-PORT intervals on the overall survival (OS) of patients with head and neck squamous cell carcinoma (HNSCC). METHODS: The National Cancer Data Base was reviewed for the period of 2006-2014, and patients with HNSCC undergoing surgery and PORT were identified. Kaplan-Meier survival estimates, Cox regression analysis, and propensity score matching were used to determine the effects of initiating PORT within 6 weeks of surgery and different time-to-PORT intervals on survival. RESULTS: This study included 41,291 patients. After adjustments for covariates, starting PORT >6 weeks postoperatively was associated with decreased OS (adjusted hazard ratio [aHR], 1.13; 99% confidence interval [CI], 1.08-1.19). This finding remained in the propensity score–matched subset (hazard ratio, 1.21; 99% CI, 1.15-1.28). In comparison with starting PORT 5 to 6 weeks postoperatively, initiating PORT earlier was not associated with improved survival (aHR for ≤ 4 weeks, 0.93; 99% CI, 0.85-1.02; aHR for 4-5 weeks, 0.92; 99% CI, 0.84-1.01). Increasing durations of delay beyond 7 weeks were associated with small, progressive survival decrements (aHR, 1.09, 1.10, and 1.12 for 7-8, 8-10, and >10 weeks, respectively). CONCLUSIONS: Nonadherence to NCCN guidelines for initiating PORT within 6 weeks of surgery was associated with decreased survival. There was no survival benefit to initiating PORT earlier within the recommended 6-week timeframe. Increasing durations of delay beyond 7 weeks were associated with small, progressive survival decrements. Cancer 2017;123:4841-50. © 2017 American Cancer Society.