Effect of waiting time for radiotherapy after last induction chemotherapy on prognosis of locally advanced nasopharyngeal carcinoma

Background: The effect of radiotherapy waiting time after last induction chemotherapy (IC-RT) on prognosis of patients with locally advanced nasopharyngeal carcinoma (LANPC) needs further discussion. Methods: Three hundred and six patients with LANPC diagnosed pathologically by induction chemotherapy (IC) and radiotherapy (RT) from 2013 to 2018 were selected for this study. Results: The IC-RT was a risk factor for the post-treatment progression of LANPC (OR = 1.017 95%CI: 1.003-1.031), For patients with LANPC, the IC-RT > 40 days significantly reduced 5-year PFS (70% vs. 55%; p = 0.0012), 5-year OS (84% vs. 73%; p = 0.028), 5-year DMFS (80% vs. 66%; p = 0.003), 5-year LRFS (77% vs. 67%; p = 0.012). Indicating that patients with stage IVa who IC-RT > 40 days were found to be a significant predictor of aggravated PFS (HR = 2.69; 95%CI: 1.57-4.6), OS (HR = 2.55; 95%CI: 1.29-5.03), DMFS (HR = 3.07; 95%CI: 1.64-5.76) and LRFS (HR = 2.26; 95%CI: 1.21-4.21). Conclusion: The prognosis of patients will be adversely affected if the IC-RT exceeds 40 days, especially for stage IVa patients.