This study aimed to assess the pre-operative
chemotherapy impact on the relationship between
estrogen receptor (ER) expression and markers of proliferation and apoptosis in primary and metastatic
breast cancer. Immunohistochemical examinations were conducted on surgically removed ductal invasive breast
cancers and their
lymph node metastases in 135 patients. A total of 64 patients from this group underwent pre-operative
chemotherapy and in 71 cases the surgery was performed without primary
chemotherapy. A negative correlation between ERα and Ki-67 was found in primary
tumors and
lymph node metastases. A positive correlation was observed between ERα and Bcl-2. A positive correlation was also noted between ERβ and Bak, suggesting that the two ERs were involved in the regulation of
proteins responsible for the control of the apoptotic process. Assessment of the expression of the
proteins conducted separately in primary
tumors and
lymph node metastases did not reveal a significant effect of pre-operative
chemotherapy on the correlations of ERs with Ki-67, Bcl-2 and Bak. However, the analysis of the correlations between the receptor expression in primary
tumors and Ki-67, Bcl-2 and Bak in
lymph node metastases showed a statistically significant impact of pre-operative
chemotherapy on the correlations of ERα and Bcl-2 with ERβ and Bak, confirming involvement of the two ERs in the regulation of apoptosis during breast
carcinogenesis.