Purpose: To determine the incidence of bone metastasis (BM) in young female patients with breast cancer (BC) and develop 2 robust nomograms for BM in young female patients with BC.
Methods: We searched and downloaded the data from young (age ≤40 years) female patients with bone cancer from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2015. Univariate and multivariate analyses were performed to screen the potential diagnostic variables and prognostic factors for BM. The diagnostic and prognostic nomograms were generated and evaluated by the area under the receiver operating characteristic (ROC) curve (AUC), calibration curves, and decision curve analysis (DCA).
Results: A total of 13 347 young female patients with BC were identified; of these, 462 were initially diagnosed as having BM. The independent risk factors for BM in young female patients with BC were tumor size, BC subtype, American Joint Committee on Cancer (AJCC) T stage, AJCC N stage, age and marital status. The independent prognostic factors in these patients were tumor size, subtype, surgery performed, lung metastasis, liver metastasis and brain metastasis. The AUC values of the diagnostic nomogram were 0.803 (95% CI; 0.795-0.811) and 0.813 (95% CI; 0.800-0.825) in the training and validation cohorts, respectively. The time-dependent AUC values of prognostic nomogram were 0.850, 0.853, and 0.824 at 2, 3 and 4 years in the training cohort, and also >0.700 in the validation cohort. For both nomograms, the discrimination was higher than all independent variables. Calibration curve and decision curve analysis (DCA) indicated that both nomograms had favorable calibration and clinical utilization. Finally, a risk stratification system was generated and the 3 risk subgroups showed significantly distinct prognoses.
Conclusions: A total of 2 nomograms were developed to assess the risk for and in prognosis of young female patients with BC with BM (BCBM).