The prognostic and predictive value of the 8th American Joint Committee on Cancer (AJCC) staging system among early breast cancer patients aged

Abstract

This study respectively analyzed the prognostic value and the role in treatment decision-making [breast-conserving surgery (BCS) + radiotherapy (RT) or mastectomy (MAST)] of the 8th American Joint Committee on Cancer (AJCC) pathological prognostic staging system compared with the 7th AJCC anatomical staging system among early breast cancer patients aged <50 years. Patients with T1-2N0M0 breast cancer aged <50 years were extracted from the Surveillance, Epidemiology, and End Results database between 2010 and 2014. Breast cancer-specific survival (BCSS) was used as the primary endpoint. Chi-squared test, receiver operating characteristics analysis, Kaplan-Meier method, and multivariate Cox proportional models were used to conduct statistical analysis. A total of 22,640 female patients were identified, and 24.4% of them reallocated to new stage groups from the 7th to the 8th AJCC staging. Among them, 46.2% (n=10,450) and 53.8% (n=12,190) of patients received BCS + RT and MAST, respectively. The 8th AJCC staging system was an independent prognostic factor for BCSS. Patients treated with BCS + RT had better BCSS compared to those treated with MAST (P<0.001). According to the 8th AJCC staging, BCS + RT could improve 5-year BCSS compared with MAST in patients with stage IA (P=0.006) and stage IB (P=0.001) diseases, while comparable BCSS was found between the two treatment arms in patients' stage IIA disease (P=0.366). Multivariate analyses replicated similar findings after stratification by the 8th AJCC stages. In patients with T1-2N0 breast cancer and aged <50 years, the 8th AJCC pathological staging system provides accurate prognostic information than the 7th anatomical staging. BCS + RT is the optimal local management for stage IA and IB diseases, while it is the optional management in stage IIA disease according to the 8th AJCC staging.