Study on Intratumoral Heterogeneity of Expression of Estrogen Receptor, Progesterone Receptor, and Human Epidermal Growth Factor Receptor 2 in Carcinoma Breast

Aim: The aim of this study was to study intratumoral heterogeneity in the expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) between two different cores/blocks of core needle biopsy (CNB), two different blocks of the same lesion in resection specimen (RS), and in between the CNB and RS. Materials and Methods: This is a prospective observational study of all the cases of breast carcinoma received in the department of histopathology for 2 years. All the patients with breast carcinoma diagnosed by CNB and RS were analyzed by three pathologists independently by immunohistochemistry. Results: Of the 75 cases, 74 were females and 1 male with a peak incidence of 60–70 years. Invasive breast carcinoma of no special type (97%) was the most common, followed by invasive lobular carcinoma (3%). Grade III tumors (44%) were more common, followed by Grade II (39%) and Grade I (17%). ER and PR showed a concordance rate of 96% ( P < 0.05), whereas the HER2 showed a concordance rate of 93% ( P < 0.05%). The concordance of ER decreased with increasing tumor size and grade, while PR and HER2 showed variable concordance with tumor size and grade. Conclusion: The concordance rate of ER and PR (96%) was higher than (93%) HER2. In most cases, biomarker expression in core biopsy and single tumor block was reflective of breast carcinoma as a whole. However, because of the heterogeneous expression of biomarkers, we recommend testing tumors with negative biomarker expression on CNB, again on the RS.