The clinicopathologic characteristics and prognostic significance of triple-negativity in node-negative breast cancer

BACKGROUND: Triple-negative (TN) breast cancer, which is defined as being negative for the estrogen receptor (ER), the progesterone receptor (PR), and the human epidermal growth factor receptor 2 (HER-2), represents a subset of breast cancer with different biologic behaviour. We investigated the clinicopathologic characteristics and prognostic indicators of lymph node-negative TN breast cancer. METHODS: Medical records were reviewed from patients with node-negative breast cancer who underwent curative surgery at Seoul National University Hospital between Jan. 2000 and Jun. 2003. Clinicopathologic variables and clinical outcomes were evaluated. RESULTS: Among 683 patients included, 136 had TN breast cancer and 529 had non-TN breast cancer. TN breast cancer correlated with younger age (< 35 y, p = 0.003), and higher histologic and nuclear grade (p < 0.001). It also correlated with a molecular profile associated with biological aggressiveness: negative for bcl-2 expression (p < 0.001), positive for the epidermal growth factor receptor (p = 0.003), and a high level of p53 (p < 0.001) and Ki67 expression (p < 0.00). The relapse rates during the follow-up period (median, 56.8 months) were 14.7% for TN breast cancer and 6.6% for non-TN breast cancer (p = 0.004). Relapse free survival (RFS) was significantly shorter among patients with TN breast cancer compared with those with non-TN breast cancer (4-year RFS rate 85.5% vs. 94.2%, respectively; p = 0.001). On multivariate analysis, young age, close resection margin, and triple-negativity were independent predictors of shorter RFS. CONCLUSION: TN breast cancer had higher relapse rate and more aggressive clinicopathologic characteristics than non-TN in node-negative breast cancer. Thus, TN breast cancer should be integrated into the risk factor analysis for node-negative breast cancer.