The aim of this study was to investigate the correlation between the expression of S100A4 and the efficacy of neoadjuvant chemotherapy in breast cancer. A total of 65 patients with invasive breast cancer were treated with neoadjuvant chemotherapy using the TAC regimen. The expression of S100A4 was detected by an immunohistochemical two-step method prior to treatment, after 2 cycles of chemotherapy and after 4 cycles of chemotherapy. Pathological evaluations of the chemotherapy were performed using the Miller and Payne (MP) grading system and their correlation with the changes of S100A4 expression during and after the treatment were explored. Between pre-neoadjuvant chemotherapy and 4 cycles post-chemotherapy, there was a significant difference in the expression of S100A4 (P<0.05); S100A4 expression was associated with neoadjuvant chemotherapy. However, between pre-neoadjuvant chemotherapy and 2 cycles post-chemotherapy, there was no significant difference in the expression of S100A4 (P>0.05). The intensity and changes of S100A4 expression were positively correlated with the efficacy of neoadjuvant chemotherapy (r=0.259, P<0.05). When patients with an MP grade of I or II following the second cycle of neoadjuvant chemotherapy were continually treated with the original chemotherapy for another 2 cycles, the desired effect was generally not achieved. S100A4 may be used as a predictor of the efficacy of neoadjuvant chemotherapy in breast cancer, guiding the formulation of individualized programs to improve the effectiveness of the treatment. For patients with an MP grade level of I or II after 2 cycles of neoadjuvant chemotherapy, the use of alternative chemotherapy regimens should be considered.
Keywords: S100A4; breast cancer; coarse needle biopsy; high frequency color Doppler ultrasound; neoadjuvant chemotherapy.