A Clinicopathological Study of CK5/6 and EGFR Expression in Triple-Negative Breast Cancers

Background and Objective: Triple-negative breast cancer (TNBC) is an aggressive and heterogeneous subtype of breast cancer. Cytokeratin 5/6 (CK5/6) and epidermal growth factor receptor (EGFR) are basal markers that may be associated with tumour characteristics. This study aimed to evaluate CK5/6 and EGFR expression in TNBC and determine their association with clinicopathological parameters. Materials and Methods: This hospital-based, observational cross-sectional study included 34 consecutive patients diagnosed with TNBC at Government Kilpauk Medical College and Hospital over six months. Tumour specimens were examined histopathologically, and immunohistochemistry was performed to assess CK5/6 and EGFR expression. Associations with age, tumour size, histological grade, pathological stage, tumour-infiltrating lymphocytes, lymph node metastasis and Ki-67 index were analysed using Fisher's exact test. A p-value <0.05 was considered statistically significant. Results: The mean age of patients was 52.9 years. Most tumours measured 2–5 cm (52.9%), were histological grade 2 (61.8%) and belonged to stage II (52.9%). CK5/6 positivity was observed in 14 cases (41.2%), while EGFR positivity was detected in 18 cases (52.9%). Both markers were positive in 12 cases (35.3%), and 20 cases (58.8%) expressed at least one marker. EGFR expression showed a statistically significant association with tumour size (p=0.049). Neither marker showed a significant association with the other clinicopathological parameters studied. Conclusion: CK5/6 and EGFR showed variable expression in TNBC. EGFR expression was associated with tumour size, although this finding requires cautious interpretation because of the small sample size and multiple comparisons. Larger studies with clinical follow-up are needed to establish the prognostic relevance of these markers.