The prognostic value of the 8th edition of the American Joint Committee on Cancer (AJCC) staging system in triple-negative breast cancer

The American Joint Committee on Cancer (AJCC) released its 8th edition of cancer staging implemented in early 2018. This study aims to compare anatomic staging (AS) with prognostic staging (PS) based on the updated AJCC 8th edition staging manual. A retrospective single-center analysis of 313 triple-negative breast invasive ductal carcinoma patients who received surgery at department of breast surgery in the Fourth Hospital of Hebei Medical University from 01/2010 -12/2012 was performed. All cases were restaged using the AJCC 8th edition AS and PS system. The 7-year disease-free survival (DFS) and the 7-year overall survival (OS) rates were 76.30% and 78.27%, respectively. Applying the PS system, 277 (88.5%) patients of the AS groups were upstaged to the PS groups, 31 cases with IIIC and 5 cases with IV unchanged (11.5%) and no cases downstaged. Both 7-year DFS and 7-year OS were significantly different in the different AS and PS groups (all, p<0.001). The PS system was found to provide better prognostic information in patients with AS group IIB. A total of 43 patients with AS group IIB were upstaged by PS system, in which 30 patients were +2 upstaged to PS IIIB, and 13 patients were +3 upstaged to PS IIIC. PS IIIB and IIIC from AS IIB had significant differences in 7-year DFS (chi(2)=5.628, p=0.014) and 7-year OS (chi(2)=6.037, p=0.018). Both AS and PS systems proposed in the 8th edition of the AJCC breast cancer staging manual had prognostic value in TNBC. Moreover, the PS system predicts clinical outcomes of TNBC patients more accurately than the traditional AS system.