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.