Abstract
BACKGROUND: The incidence of breast cancer is increasing among young women, yet the prognostic implications of stage I-III breast cancer remain unclear. This study aimed to identify independent prognostic factors and develop a validated nomogram to predict clinical outcome in young breast cancer patients using data from the Surveillance, Epidemiology, and End Results (SEER) database. METHODS: Patients aged 15-39 years diagnosed with stage I-III breast cancer were identified from the SEER database. The cohort were randomly divided in a 7:3 ratio into a training set and a validation set. Univariate and multivariate Cox regression analyses were conducted to evaluate risk factors for overall survival (OS). These risk factors were utilized to construct a nomogram model predicting 5-year survival of stage I-III young breast cancer patients. In the training cohort, a prognostic nomogram was developed using Cox regression analysis and subsequently tested in the validation cohort. Model performance was assessed using concordance indices (C-indices) and calibration curves. RESULTS: A total of 14,860 patients with stage I-III breast cancer between 2010 and 2016 were included in the study. Prognostic factors included in the Cox proportional hazards model were histologic grade, tumor (T) stage, node (N) stage, estrogen receptor (ER) status, progesterone receptor (PR) status, and human epidermal growth factor receptor 2 (HER2) status of breast cancer (P<0.05). The nomogram demonstrated good predictive performance for 5-year OS with a C-index of 0.765 [95% confidence interval (CI): 0.760-0.772] in the training set and 0.771 (95% CI: 0.765-0.777) in the validation set. CONCLUSIONS: The nomogram model showed significant accuracy in predicting 5-year OS in young women with stage I-III breast cancer. While it holds promise for supporting patient counseling and individualized treatment planning, further external validation is warranted before its routine clinical application.