Improved Prognostication for the Updated AJCC Breast Cancer Pathological Prognostic Staging Varied in Higher-Stage Groups.

ABSTRACT

BACKGROUND: In addition to TNM-based anatomical staging (AS), a novel pathological prognostic staging (PPS) has been proposed by the American Joint Committee on Cancer (AJCC). PPS demonstrated better prognostication, but its superiority in breast cancer subtypes and related to staging discrepancies between AS and PPS are not clear. METHODS: A cohort of 1729 patients with breast cancer was staged into AS and PPS according to the latest AJCC staging. Patient characteristic and restaging outcomes were compared. RESULTS: Compared with AS, 799 and 135 cases were upstaged and downstaged respectively in PPS, mostly involved stage I cases. For the overall cohort, PPS demonstrated superior prognostic power over AS in both disease-free survival (DFS) and breast cancer-specific survival. However, such superiority was found mainly in estrogen receptor (ER)/progesterone receptor (PR)+ but not ER-PR- cancers. Comparing the restaged cases within the same PPS, PPS 1A cases showed similar survival irrespective of the original AS. Interestingly, in other PPS groups (PPS 1B and higher), there was a difference in outcome among patients with same PPS but different AS. Within PPS 1B patients, downstaged cases from higher AS showed worse DFS (3A>1B vs. 2A>1B χ2 = 4.732, P = .030). CONCLUSIONS: PPS may provide a more accurate prognostication, mostly among ER/PR+ cancers and with PPS 1A patients. Patients restaged to higher PPS stages showed significant differential survival even within the same PPS. Also, only limited improvement was observed for ER-PR- cancers. Caution needs to be exercised in using PPS for patient prognostication, as in some cases the outcome can be variable with the same PPS.