Objective  To analyze the differences in clinicopathologic features and expressions of some immunohistochemical indicators between triple negative breast cancer and non-triple negative breast cancer, and to investigate the relationship between clinicopathological features and immunohistochemical indicators.

  Methods  A total of 863 patients (135 triple negative breast cancer and 728 non-triple negative breast cancer) with histopathologically confirmed breast cancer were collected in Peking Union Medical College Hospital from January 2010 to December 2013.We retrospectively analyzed the difference in the onset age, histological subtype, tumor size, tumor differentiation, tumor stages, lymph node metastasis, nipple involvement and operation method between triple negative breast cancer and non-triple negative breast cancer, then explored the difference between them in the expressions of estrogen receptor β (ERβ), epidermal growth factor receptor (EGFR), P53, and Ki67 by immunohistochemical staining. Prognostic factors of triple negative breast cancer were further discussed by univariate survival analysis.

  Results  The proportion of invasive ductal carcinoma in triple negative breast cancer was higher than that in non-triple negative breast cancer (86.7% vs. 65.2%, P < 0.001); the age of onset was younger in triple negative breast cancer(46.0±10.6) years vs. (51.0±3.3) years, P < 0.05;significant differences were also found in lymph node metastasis, tumor size, differentiation grade, surgical procedure, and tumor stages between the two groups(P < 0.05); no statistically significant inter-group difference in nipple involvement (P > 0.05). Immunohistochemical results showed that compared with non-triple negative breast cancer, ERβ expression rate decreased significantly(63.7% vs. 75.6%, P < 0.05)while EGFR expression rate increased significantly in triple negative breast cancer(62.2% vs. 33.3%, P < 0.05); the expression of P53 and Ki67 demonstrated no significant difference(P > 0.05). The overall survival(OS)and relapse-free survival(RFS)were both lower in triple negative breast cancer(P < 0.05). Univariate survival analysis showed that both ERβ negative expression and EGFR positive expression were related to the poor prognosis of triple negative breast cancer (P < 0.05).

  Conclusions  Compared with non-triple negative breast cancer, triple negative breast cancer shows completely different clinicopathological features:younger age of onset, larger tumor size, lower degree of differentiation, higher incidence of lymph node metastasis, lower ERβ expression, higher EGFR expression, and lower OS and RFS.ERβ and EGFR may be important prognostic indicators in triple negative breast cancer.