LAUSR

Evaluation of expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2/neu) receptor was carried out on 80 breast cancer patients before and after neoadjuvant chemotherapy (NAC). No differences in expression were noted in 89% with reference to ER, 95% with reference to PR, and 91% with reference to HER2/neu status. A change in receptor status from positive to negative was noted in 12% for ER, 5% for PR, and 21% for HER2/neu after NAC. A negative to positive shift was noted in 11% for ER, 4% for PR, and 4% for HER2/neu after NAC. The possible reasons ascribed for change in receptor status after NAC are as follows: (1) Selection of chemoresistant clones with different receptor expression after NAC. (2) Tumor heterogeneity with variable receptor expression in different areas. (3) Ovarian suppression during NAC leading to alteration in receptor expression. (4) Technical considerations such as staining techniques and intra-observer and inter-observer differences in IHC slide interpretation before and after NAC.