Fig. 3

Establishment and validation of a nomogram risk prediction model for BM in NSCLC. a The nomogram for predicting the risk of brain metastasis in NSCLC patients. To use it, draw a vertical line upward from each variable and record the corresponding score. Finally, sum all the scores, and the vertical projection from Total Points to Risk of BM corresponds to the predicted probability of brain metastasis in lung cancer. The predicted low and high values of CEA are interpreted as < 5 ng/ml and ≥ 5 ng/ml, respectively. Low and high NLR values are interpreted as < 5.021 and ≥ 5.021, and low and high LMR values are interpreted as < 1.589 and ≥ 1.589. b The ROC curve of the model, with an area under the curve (AUC) of 0.849 (95% CI 0.802–0.896). c The calibration plot of the nomogram. The horizontal axis represents the predicted probability, and the vertical axis represents the actual probability. A perfect prediction corresponds to the 45° dashed line. The red and blue lines represent the observed (apparent) performance of the nomogram before and after bootstrapping (Hosmer–Lemeshow test: P = 0.73)