Validation of the pathological prognostic staging system proposed in the revised eighth edition of the AJCC staging manual in different molecular subtypes of breast cancer

The authors investigated the clinical utility of the revised prognostic staging system proposed in the eighth edition of the American Joint Committee on Cancer (AJCC) staging manual in breast cancer (BC) patients. We retrospectively reviewed the data of 714 BC patients that received surgical treatment and standard adjuvant therapy from January 2005 to December 2007. All patients were restaged for anatomic TNM stage and pathological prognostic (PP) stage as defined in the revised eighth edition of the AJCC manual. Compared with anatomic stage, PP stage was different from anatomic stage in 325 (45.5%) patients, 254 were down-staged and 71 were upstaged. There were significant differences in overall survival (OS) and disease-free survival (DFS) according to different anatomic stages or PP stages (all, p < 0.001). In anatomic stage I patients, OS was significantly different between PP stages IA and IB (p < 0.001), but no significant difference was observed between anatomic stages IA and IB (p = 0.413). PP stages exhibited significant OS differences in anatomic stage IIB (p = 0.011), but survival differences according to PP stages were not observed in anatomic stage IIA, IIIA, or IIIC. PP stages were found to have prognostic value with respect to OS and DFS for luminal (p < 0.001 and p < 0.001), HER2-positive (p = 0.001 and p = 0.013), and triple-negative (p = 0.008 and p = 0.03) subtypes. The prognostic staging system proposed in the eighth edition of the AJCC more accurately predicts the clinical outcomes of BC patients than the traditional anatomic staging system.