Derivation and external validation of a prognostic nomogram for HER2-negative early breast cancer in young Chinese females: A population-based study.

Abstract

e12728 Background: Young breast cancer (YBC) is a distinct subtype, marked by aggressive tumor biology, and worse overall survival. HER2-negative breast cancer, accounting for 70-75% of cases, poses a significant challenge due to the absence of targeted therapies. Despite treatment advances, young women with HER2-negative early-stage breast cancer continue to have poor outcomes, underscoring the need for accurate prognostic tools to guide personalized treatment strategies. Methods: This study analyzed 7,863 patients with HER2-negative early YBC from the SEER database, diagnosed between 2010 and 2015. Independent prognostic factors were identified through univariate and multivariate Cox analyses. These factors were used to develop a nomogram predicting 3- and 5-year overall survival (OS). External validation was performed with data from 138 patients. Results: Tumor grade, estrogen receptor (ER) status, histology, T stage, N stage, and surgery type, were incorporated into the nomogram. The concordance indices (C-index) for the nomogram were 0.739 (95% CI: 0.723-0.755) in the training set, 0.748 (95% CI: 0.723-0.773) in the internal-validation set, and 0.711 (95% CI: 0.573-0.848) in the external validation set. Time-dependent ROC analysis demonstrated strong discrimination. Calibration curves confirmed the high predictive precision, and decision curve analysis (DCA) validated its clinical utility. Risk stratification indicated significantly better OS in high-risk patients compared to low-risk patients (p < 0.05). Conclusions: The prognostic nomogram developed in this study offers a reliable and clinically useful tool for predicting OS in young women with HER2-negative early breast cancer, facilitating more informed treatment decisions and improving patient outcomes. Baseline characteristics of HER2 negative early YBC included from SEER database and Chinese PLA General Hospital. Variable Training Set (N = 5,507) Internal Validation Set (N = 2,356) External Validation Set (N = 138) p-value 1 Age (median, IQR) 36.0 (32.0-38.0) 36.0 (32.0-38.0) 36.0 (33.0-38.0) 0.2 Age Group 18-35 years (49%) 18-35 years (48%) 18-35 years (42%) 0.3 Marital Status Married (61%) Married (61%) Married (95%) <0.001 Grade G1 (9.9%), G2 (35%), G3/G4 (55%) G1 (10%), G2 (34%), G3/G4 (56%) G1 (2.9%), G2 (62%), G3/G4 (35%) <0.001 Histology IDC (92%) IDC (92%) IDC (90%) 0.94 T stage T1 (40%), T2 (46%), T3 (11%) T1 (39%), T2 (47%), T3 (11%) T1 (47%), T2 (48%), T3 (2.9%) 0.052 N stage N0 (52%), N1 (35%) N0 (53%), N1 (35%) N0 (54%), N1 (25%) 0.009 ER Status 2 Positive (71%) Positive (72%) Positive (72%) 0.6 PR Status 2 Positive (63%) Positive (64%) Positive (74%) 0.016 Surgery Type Mastectomy (62%) Mastectomy (61%) Mastectomy (83%) <0.001 1 Kruskal-Wallis rank sum test; Pearson's Chi-squared test. 2 Abbreviations: Estrogen receptor, ER; Progesterone receptor, PR.