Accumulation of p53 determined by immunohistochemistry as a prognostic marker in node negative breast cancer; analysis according to St Gallen consensus and intrinsic subtypes.

BACKGROUND: This study evaluated the prognostic impact of p53 accumulation by immunohistochemistry (IHC) in lymph node-negative breast cancer (LNN-BC), and in subgroups of St Gallen consensus and intrinsic subtypes.
METHODS: A total 845 with a pathologic diagnosis of LNN-BC patients that underwent surgery at the National Cancer Center, Korea between 2001 and 2005 were retrospectively reviewed.
RESULTS: The median age was 48 years (range: 25-85) and median follow-up period was 66.0 months (range: 9-101). Univariate analysis determined that tumor size, estrogen receptor (ER), progesterone receptor (PgR), p53, and Ki-67 were significant for disease free survival (DFS). Of these factors, PgR negativity (HR 3.57; 95% CI 1.26-10.09; P = 0.01) and p53 positivity (HR 3.17; 95% CI 1.51-6.65; P = 0.002) were independent prognostic factors in multivariate analysis. In the subanalysis for 4 intrinsic subtypes (luminal A, luminal B, HER2-overexpression, and triple-negative subtypes) and risk groups by St Gallen consensus, there were significant differences of DFS rates by p53 (5-year DFS rate, luminal A; 97.2% for p53 (-) vs 93.8% for p53 (+); P = 0.03, triple-negative subgroups; 94.1% vs 78.7%; P = 0.002, intermediate-risk group; 96.5% vs 90.7%; P = 0.003).
CONCLUSIONS: P53 has prognostic power in LNN-BC, and gives the additional prognostic information for intrinsic subtypes and St Gallen consensus.