Changes of biological features in breast cancer cells determined by primary chemotherapy

Background. To evaluate the changes in the biological features of breast cancer cells induced by primary chemotherapy (PCT) and their possible relationship with the response to therapy, we performed an extensive immunohistochemical study before and after PCT. Patients and methods. PCT was administered to 29 women with breast cancer. On specimens obtained by tru-cut and post-chemotherapy surgery we analyzed the following parameters: histology, histologic grade, apoptotic index, hormone receptor levels, Ki67, PCNA, EGFr, bcl-2, p53, p170. The significance of the changes induced by PCT and their correlations with the type of response were evaluated. Results. Twelve patients achieved a partial response with PCT. No baseline biological parameter correlated with the type of response. After PCT we observed a significant increase in the apoptotic index (p = 0.000), PCNA (p = 0.036), EGFr (p = 0.005), and p170 expression (p = 0.001), regardless of the type of chemotherapy administered (anthracyclines, 25 cases, or CME 4 cases). Responder patients displayed a significant decrease in ER levels (p = 0.015), whereas in non responders there was an increase in PCNA (p = 0.008) and EGFr expression (p = 0.002). The apoptotic index and p170 expression rose after PCT regardless of the type of response. Conclusions. PCT induced significant variations in the phenotype of breast cancer cells. These changes might reflect the selection of new neoplastic clones with different biological properties and so could facilitate the choice of appropriate chemotherapy agents.