An insight into immunohistochemical profile of triple negative breast carcinoma in a tertiary care center

Abstract

Introduction: Triple Negative Breast Cancer (TNBC) is a type of breast cancer that fails to express Estrogen Receptor (ER), Progesterone Receptor (PR) and Human Epidermal Growth Factor Receptor 2 (HER2) in Immunohistochemical analysis. TNBC has a unique molecular profile, aggressive nature and lack of efficient targeted therapies. The aim of the study was to evaluate the expression of basal markers like Epidermal Growth Factor Receptor (EGFR) and Cytokeratin 5/6 (CK 5/6) and to correlate their expression with the clinico-pathological parameters, thus enabling the identification of the aggressive basal like phenotype of TNBC in resource-constrained settings. Methodology: The study was conducted at a South Indian tertiary care centre for 2 years. Data such as age of presentation, tumour measurements, margins and necrosis, numbers, levels and sizes of lymph nodes were collected. Data on histological type and grade, in situ component, lymphovascular and perineural invasion, stromal reaction and lymph node status were recorded. Primary Immunohistochemical studies were performed for the markers ER,PR and HER2.Patients with negative expression for all the three markers were identified. IHC studies for EGFR and Cytokeratin 5/6(CK5/6) were done on tissue blocks and the expression of these two markers were equated with the clinico-pathological parameters. Results: Among the 94 cases, 44 cases (46.8%) expressed CK5/6 and 46 (48.9%) expressed EGFR. A plausible association was noted between the expression of the two markers with age of the patient, tumour size, histological grade and tumour necrosis. Conclusion: Combination of the time honoured gross and histopathological examinations along with the application of basal markers like CK 5/6 and EGFR, helps in identifying the basal-like phenotype with dismal clinical outcome among the triple-negative breast cancers in resource-constrained settings. An insight into such an aggressive tumour, provided by these markers may be critical in designing personalized treatment strategies for such patients.