Derivation and external validation of a prognostic nomogram for human epidermal growth factor receptor 2 negative early young breast cancer in women

Young breast cancer (YBC) tends to have more aggressive phenotypes and poorer survival outcomes. This study aimed to derive and validate a prognostic nomogram for human epidermal growth factor receptor 2 (HER2)-negative early YBC.

A total of 7863 patients diagnosed with HER2-negative early YBC between 2010 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database were enrolled. Patients were randomly divided into a training and an internal validation set. To further evaluate the performance of the nomogram, we enrolled patients diagnosed with YBC at Chinese PLA General Hospital using the same inclusion and exclusion criteria. In training set, univariate and multivariate Cox analyses were performed to select independent prognostic factors, which were then used to develop a nomogram to predict the 3- and 5-year overall survival (OS). Calibration curves, concordance index (C-index), receiver operating characteristic curves (ROC), decision curve analysis (DCA) and Kaplan–Meier survival analysis were used to assess the accuracy and clinical utility of the model. The accuracy and predictive ability of the model were confirmed through validation with both the internal and external validation sets.

Multivariate Cox analysis revealed that grade, estrogen receptor, histology, T stage, N stage, and surgery were independent prognostic factors, which were used to construct the nomogram. The C-indexes of the nomogram in the training, internal and external validation sets were 0.739 (95% confidence interval [CI]: 0.723–0.755), 0.748 (95% CI 0.723–0.773) and 0.711 (95% CI 0.573–0.848) respectively. The results of ROC curve analysis indicated good discrimination of the nomogram. Calibration curves revealed the high forecast precision of the nomogram. DCA curves and results of risk stratification showed the clinical usability of the nomogram, with better OS in the low-risk group than in the high-risk group (all P < 0.05).

Our prognostic nomogram has good accuracy, forecasting precision, and clinical usability for predicting OS in HER2-negative early YBC.