OBJECTIVETo investigate the correlation of CK5/6 and CK17 expression with clinical outcome in patients with triple-negative [ER(-), PR(-), Her-2(-)] breast cancer.

METHODS112 patients with breast cancer treated by surgery between 2000 and 2002 were included in this study. All cases were immunohistochemically proven to be triple-negative. Samples of formalin-fixed and paraffin-embedded surgical specimens were obtained for immunohistological examination for CK5/6 and CK17 expression. The correlation of the gene expression with clinicopathological features and outcome of the patients was analyzed.

RESULTSOf the 112 triple-negative patients, five-year disease-free survival rate was 73.2% (82/112). The positive rate of both CK5/6 and CK17 was 21.4% (24/112), either CK5/6 or CK17 positive was 46.4% (52/112). It was shown by Kaplan-Meier curve that positive CK5/6, CK17 or CKs (CK5/6 or CK17 positive) was correlated with poor five-year disease-free survival (P = 0.020, P = 0.032, P = 0.003); and positive staining of CK5/6 or CKs was correlated with poor five-year overall survival (P = 0.027, P = 0.015). Of the 91 patients with invasive ductal carcinoma, a correlation of CK5/6 or CK17 positive staining with high grade differentiation was observed (P = 0.030), and with axillary lymph node metastasis was also noticed (P = 0.044). Multivariate analysis by Cox regression showed that differentiation grade, pathological stage and expression of CK5/6 were factors affecting both the disease-free-survival and overall-survival, while menopausal status was an independent factor affecting the disease-free-survival.

CONCLUSIONPositive expression of CK5/6 or CK17 in patients with triple-negative breast cancer is correlated with poor prognosis, high grade differentiation and axillary lymph node metastasis.