Follow-up and statistical analysis
The survival stage and prognosis of all patients were followed up by
means of telephone return visits, outpatient reexaminations, and other
methods. Follow-up period was once every 3 months in the first and
second years and once every 6 months in the third to fifth years. The
re-examination included physical examination, laryngoscopy and imaging
examination (cervicothoracic enhanced CT). Patients with clinically
suspected tumour recurrence were examined by PET–CT. Survival rate was
analysed via Kaplan–Meier analysis. The difference between groups was
tested through log-rank method, and independent prognostic factors were
analysed by Cox regression model in multivariate survival analysis. The
statistical software SPSS 25 was used to analyse the data.
P<0. 05 was considered statistically significant.