Prognostic Impact of EGFR and CK5/6 as Basal Markers in Triple-Negative Breast Cancers

Background: Triple-negative breast cancer (TNBC) is characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and HER2neu expression. It is a high-risk group of breast cancers, classified into aggressive basal and less aggressive non-basal subtypes. Objective: This study examines the expression of basal markers, including epidermal growth factor receptor (EGFR) and cytokeratin 5/6 (CK5/6), in TNBC cases and correlates the results with Ki-67 expression, clinicopathological parameters, and patient survival to determine prognosis and therapeutic strategies. Materials and Methods: Ninety-seven TNBC cases from January 2012 to July 2015 were included based on ER, PR, and HER2neu negativity. Tissue specimens were stained using immunohistochemistry to detect EGFR, CK5/6, and Ki-67. Statistical analysis was conducted using SPSS software version 21 to compare basal and non-basal TNBC. Results: Seventy-five (77.3%) of the TNBC specimens exhibited positive basal markers (EGFR and/or CK5/6), high Ki-67 proliferation rates, and poor prognostic parameters, including overall survival (OS) and progression-free survival (PFS). Conclusion: The 'triple-negative' designation alone is insufficient as a surrogate for 'basal expression.' Basal subtypes of TNBC demonstrate more aggressive behavior and better predict breast cancer survival.