Novel CT Radiomics Nomograms for Prediction of EGFR Mutations and Ki-67 Proliferation Index in Non-Small Cell Lung Cancer: A Multicentre Study

Background: We developed and validated the novel radiomic nomograms to identify EGFR mutations and the Ki-67 proliferation index (PI) in patients with non-small cell lung cancer (NSCLC).Methods: We enrolled 132 patients with histologically verified NSCLC from four hospital institutions, who all underwent CT scans. EGFR mutation status and Ki-67 PI were measured based on tumor tissues. A total of 1287 radiomic features were extracted based on the tumor volume of interest (VOI) manually delineated by ITK-Snap. Then, a three-stage feature selection method was implemented to acquire the most valuable radiomic features. Finally, the radiomic scores and nomograms of two tasks were established and tested, respectively. The receiver operating characteristic (ROC) curve, the area under ROC curve (AUC), calibration curve, and decision curve were used to evaluate the prediction performance and clinical utility.Findings: In task (1), smoking status and histological type were significantly associated with EGFR mutations. After feature selection, 10 features were used to establish radiomic score, which showed good performance (AUC = 0.800) in the validation cohort. The radiomic nomogram had an AUC of 0.891 (95% CI, 0.820 to 0.962) with a C-index of 0.891 in the primary cohort, and an AUC of 0.798 (95% CI, 0.664 to 0.931) with a C-index of 0.798 in the validation cohort. In task (2), gender, smoking status, histological type, and stage showed a significant correlation with Ki-67 PI expression. A total of 28 features were selected to develop a radiomic score, with an AUC of 0.820 in the validation cohort. The final nomogram showed an AUC of 0.981 (95% CI, 0.961 to 1) with a C-index of 0.981 in the primary cohort, and an AUC of 0.828 (95% CI, 0.703 to 0.953) with a C-index of 0.828 in the validation cohort.Interpretation: The EGFR mutations and Ki-67 PI in NSCLC can be predicted efficiently by the novel radiomic scores and nomograms, thus providing a useful non-invasive strategy for assessing EGFR mutation status and cell proliferation.Funding: None to declare. Declaration of Interest: The authors have declared that no competing interest exists.Ethical Approval: This retrospective study was approved by the ethics committees, and the informed consent requirement was waived.