Validation and comparison of CS-IHC4 scores with a nomogram to predict recurrence in hormone receptor-positive breast cancers

The aim of this study was to both develop and validate a nomogram based on the Ki-67 index to predict recurrence. We constructed a nomogram using the Cox proportional hazards model with 953 N0 and N1 postoperative hormone receptor (HR)-positive breast cancer patients and validated it in an external cohort of 895 patients. A prognostic model that used classical variables, Adjuvant! Online, St. Gallen risk stratification, and the four immunohistochemistry (IHC) markers (IHC4 score) was created and assessed by the likelihood ratio χ² (LR-χ²) test using the bootstrapping method. The nomogram showed an area under the receiver operating characteristic curve (AUC) of 0.75 (95% CI 0.72-0.77) in the training set. The validation set showed good discrimination with an AUC of 0.63 (95% CI 0.60-0.66). In the LR-χ² test, the nomogram score was found to be more informative than the IHC4 with clinical score (CS) [LR-χ² 13.365 (1 d.f.); 95% CI 2.50-24.23 for CS-IHC4 + nomogram score vs. CS-IHC4] on distant recurrence-free survival. This study implies that the amount of prognostic information contained in the nomogram is superior to that in the CS-IHC4 score in HR-positive N0 and N1 breast cancer patients (NCT1273415).