Statistical analysis
All statistical analysis was performed using STATA version 14.2. The
Kolmogorov-
Smirnov test was used to evaluate the probability distribution of the
samples with the reference data. Categorical data were described as
median and percentages. A receiver operating characteristic (ROC) curve
analysis was performed to identify the nodal volume’s optimal cut-off
value with the highest possible sensitivity and specificity. For
survival analysis, the Kaplan-Meier method and the log-rank test were
used. The Cox proportional hazard model and the univariate and
multivariate analysis were performed to evaluate the prognostic factors.
Overall survival, disease-free survival, and distant metastasis-free
survival were considered to determine the prognostic implications. The
p-value of <0.05 was considered statistically significant.