Fig. 3

Calibration plots of the nomogram for prediction of ypN0. (A) Calibration plot for the training cohort. The apparent and bias-corrected calibration curves (bootstrap resampling) are shown. The dashed line indicates perfect calibration. The Hosmer–Lemeshow test revealed no significant lack of fit (χ2 = 8.19, df = 7, p = 0.32). (B) Calibration plot for the validation cohort, showing similar results (χ2 = 12.07, df = 8, p = 0.15).