Study of ER, PR, HER2/neu, p53, and Ki67 expression in primary breast carcinomas and synchronous metastatic axillary lymph nodes.

Background: Breast cancer (BCA) is the second most common cancer among women in India and accounts for 7% of global burden of BCA. The axillary lymph node status is an independent prognostic factor. The combined estrogen receptor (ER), progesterone receptor (PR), and HER2/neu biomarker expression is a predictor of BCA status for therapeutic guidance. Studies have demonstrated that these biomarkers are unstable throughout their tumor progression. Varying concordance and discordance rates in the biomarker expression between primary breast carcinoma (PBC) and metastatic axillary lymph node (MALN) status are reported.

Aim: This study was conducted for studying and comparing the expression of immunohistochemistry (IHC) markers, i.e., ER, PR, HER2/neu, p53, and Ki67 between PBC and their corresponding MALN for prognostication and therapeutic purpose.

Methods: Sixty cases of PBC with metastasis to axillary lymph nodes diagnosed between years 2008 and 2014 were included in the study. A technique of manual tissue array was employed for cases subjected to IHC. Analyses of the expression of IHC markers were attempted between the PBC and their corresponding synchronous MALN and classified as concordant or discordant. Results were subjected to statistical analysis.

Results: Substantial agreement was observed for biomarker ER, PR, HER2/neu, p53, and Ki67 expression between PBC and MALN with k-value 0.79, 0.75, 0.89, 0.7, and 0.6, respectively.

Conclusion: There was high concordance for the IHC markers: ER, PR, HER2/neu, p53, and Ki67 expression in matched pairs of PBC and corresponding synchronous MALN. However, the discordance noted in small subgroups cannot be overlooked. Thus, there is a need to perform ER, PR, HER2/neu, p53, and Ki67 IHC studies routinely in both PBC and MALN to help design therapies that are tailored to target the specific tumor clones and render maximum benefit to patients.