Development of a prognostic nomogram for lymph node positive HR+/HER2-breast cancer patients: a study of SEER database and a Chinese cohort

Background: The hormone receptor+/human epidermal growth factor 2- (HR+/HER2-) breast cancer (BC) patients account for the largest proportion in all patients and are still at high risk of long-range recurrence. This current study aimed to construct a prognostic nomogram to predict 3-year and 5-year BC-specific survival (BCSS) in HR+/HER2- BC patients with axillary lymph node metastasis. Methods: A total of 25,338 HR+/HER(2- )patients with axillary lymph node-positive BC were enrolled from the Surveillance, Epidemiology and End Results (SEER) database and randomly divided into the training (n=17,738) and validation (n=7,600) cohorts using a ratio of 7:3. Univariate and multivariable Cox regression hazards were used to build a prognostic nomogram based on the training cohort. The nomogram was validated with two independent cohorts. Receiver operating characteristic (ROC) curves and calibration plots were used to evaluate the performance of the model, and Kaplan-Meier survival analyses were applied to test the clinical utility of the risk stratification system.Results: Twelve factors including age, race, marital status, grade, T stage, N stage, radiotherapy, chemotherapy, and metastasis to the bone, brain, lung and liver were identified and incorporated to construct the nomogram (P<0.001). The area under the ROC curve (AUC) values at 3-and 5-year in the training and internal validation sets were 0.800, 0.800, 0.831 and 0.819, respectively, while those of the external set were 0.765 and 0.735, indicating a satisfactory discrimination with our nomogram. The calibration curves showed highly consistent results for the actual and predicted survival probabilities. Furthermore, patients were divided into three risk groups according to the total scores of the nomogram. The risk stratification system accurately differentiated between patients with different BCSS rates.Conclusions: We constructed the first nomogram and corresponding risk stratification system to predict the 3-year and 5-year BCSS for HR+/HER2- patients with lymph node-positive BC, indicating a satisfactory accuracy and clinical application.