Discordance in Hormone Receptor and HER2 Status Between Primary Breast Cancer and Synchronous Ipsilateral Axillary...

Area of Science:

• Oncology
• Pathology
• Molecular Biology

Background:

• Estrogen receptor (ER), progesterone receptor (PR), and HER2 are critical molecular biomarkers for breast cancer management.
• Immunohistochemical analysis of these biomarkers guides treatment decisions in breast cancer patients.

Purpose of the Study:

• To evaluate the discordance rate of ER, PR, and HER2 expression between primary breast tumors and synchronous ipsilateral axillary lymph node metastases.
• To assess the clinical implications of biomarker heterogeneity in breast cancer.

Main Methods:

• A prospective analytical study involving 50 breast carcinoma cases with positive axillary lymph node metastasis.
• Immunohistochemistry was performed on both primary tumors and axillary lymph nodes to assess ER, PR, and HER2 expression.

Main Results:

• Discordance rates were observed for ER (14%), PR (12%), and HER2 (9%) between primary tumors and lymph nodes.
• Significant variations in biomarker expression, such as ER-positive primary tumors with ER-negative lymph nodes (4%) and vice versa (10%), were noted.
• Concordance rates were 86% for ER, 88% for PR, and 91% for HER2.

Conclusions:

• Significant discordance in ER, PR, and HER2 expression exists between primary breast cancer and synchronous axillary lymph nodes.
• This heterogeneity can lead to suboptimal treatment if decisions are based solely on primary tumor profiling.
• Evaluating metastatic sites alongside primary tumors is crucial for personalized breast cancer treatment strategies.