Construction and comparison of the three prediction models
T stage
The results showed that T stage, US_LNM, and PET_LNM were associated with RS_LNM. Three models with multivariate were constructed for predicting LNM, as shown in Table 
Multivariate analysis
Distinguishability of the three modelsNote: Corrected AUC by Bootstrap1000
Comparison of ROC curves for the three models. Model 3 outperformed model 1 for the sensitivity (model 3 vs. model 1, 82.86% vs. 48.57%), and outperformed model 2 for the specificity (model 3 vs. model 2, 82.02% vs. 68.54%)
Pair-wise comparisons of AUC of the three models.The AUCs of mode 1, model 2 and model 3 were significantly different
Nomogram for model 3The calibration curves for all three models showed good calibration, seen as Fig. Decision curve analysis showed that model 2 resulted in a higher degree of net benefit for all the patients than model 1, and model 3 resulted in a higher degree of net benefit for all the patients than model 2, seen as Fig. 
Calibration curves for the three models
Decision curves of the three models