Chulalongkorn Medical Journal


Background : Triple-negative breast cancer (TNBC) is defined by the lack of expressionof ER, PR and Her-2 receptors and exhibits aggressive behaviors andpoor clinical outcomes. Eighty percent of TNBCs are classified asbasal-like tumor and share clinical behaviors that are consistent with thissubtype of breast tumors.Objectives : To characterize the epidemiological features of triple-negative breastcancers (TNBC) occurring in Thai patients in terms of demographics andpathological hallmarks including the expression patterns of ER, PR,Her-2, CK5/6, CK17 and EGFR as well as clinical outcomes.Methods : In 166 TNBCs, adequate tissue samples were obtained from seventycases, and patient/tumor characteristics as well as the survival outcomeswere reviewed retrospectively.Results : The mean age was 48.04 years (range 26 – 79 years); 89% of the tumorswere invasive ductal carcinomas, and 72.4% were high-grade tumors.A high proliferative index (Ki-67 > 30%) was found in 81.4% ofthe samples. Positive staining for CK5/6 and CK17 were found in 51.4%and 55.7% of the tumors, respectively; 58.6% of the tumors had EGFRexpression. After we analyzed the expressions of ER, HER-2, CK5/6and EGFR to define the basal phenotype, 72.9% were categorized intothe basal-like group. At a median of 67.5 months, 32.5% of the tumorsrecurred and 30.1% of the patients had died. The 5-year disease-freesurvival and overall survival estimates were 69% and 74%, respectively.In multivariate Cox proportional hazards models, the basal-like subtypewas not independently correlated with DFS or OS in TNBCs (HR 1.72,[95% CI, 0.13 - 22.96], P = 0.68; for DFS and HR 2.34, [95% CI, 0.17 -31.75], P = 0.52 for OS).Conclusions : TNBCs occurred at younger age in these Thai patients than in previousstudies. We also demonstrated higher tumor grades, higher proliferationindices and inferior outcomes of TNBCs in Thai patients. Additionally,the presence of basal-like characteristics was not an independentpredictor of the survival outcome.


Faculty of Medicine, Chulalongkorn University

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