Fig. 3

The decision curve analysis for the nomogram model. a. Decision curve analysis for the nomogram predictive model. The y-axis represents the net benefit. The red line represents the nomogram model. The grey line represents the hypothesis that all patients had lymph node metastases. The black line represents the hypothesis that no patients had lymph node metastases. The x-axis represents the threshold probability. The threshold probability is where the expected benefit of treatment is equal to the expected benefit of avoiding treatment. For example, if the possibility of lymph node metastasis involvement of a patient is over the threshold probability, then a treatment strategy for lymph node metastasis should be adopted. The decision curves in the validation set showed that if the threshold probability is between 0 and 0.4, then using the nomogram to predict lymph node metastases adds more benefit than treating either all or no patients. b. The cost-benefit ratio of the nomogram predictive model. The red curve represents the number of people classified as positive (high risk) at each threshold probability; the blue curve is the number of true positives for each threshold probability