Molecular Evaluation of Subtypes of Breast Cancer by Immunohistochemical expression of Estrogen Receptor(ER), Progesterone Receptor(PR), Her2neu,Cytokeratin 5/6 and Ki 67

Shweta Mahajan, Amarjit Singh, Anita Joneja, Sudershan Kapoor

Abstract: Objective- In this study, histopathological examination and subsequent IHC staining using a panel of five Immunohistochemistry (IHC) markers i. e Estrogen Receptor (ER), Progesterone Receptor (PR), HER2neu, Cytokeratin5/6 and Ki-67 was done and on the basis of their results subtyping and molecular classification was done into Luminal A, Luminal B, Her2neu and Basal like subtypes. Materials and methods-Specimens of 50 patients with breast carcinoma were evaluated histopathologically and immunohistochemically for a panel of five IHC markers i. e. ER, PR, HER2neu, CK5/6 and Ki-67. Results- We observed that mean age of presentation was 54.86 years. Infiltrating ductal carcinoma (NOS) was the most common histological subtype with majority of the tumors classified as Grade II. We observed 27 (54 %) cases as Luminal A, 4 (8 %) Luminal B, 6 (12 %) as HER2neu and 8 (16 %) as Basal-like subtype. Remaining 5 (10 %) cases were Unclassified. Conclusion- We concluded that most common subtype was Luminal A with low proliferative activity having good prognosis as compared to Luminal B with higher proliferative index and has poor prognosis. Our study provides a basis for the use of IHC for molecular subtyping of breast cancer as an important prognostic factor as well as target for specific adjuvant chemotherapy.

Keywords: Breast cancer, Molecular classification, ER/PR, Cytokeratin5/6, Ki67