Abstract: Objective To investigate whether apollon immunoexpression in breast cancer tissues helps to predict pathological
complete response (pCR) after neoadjuvant chemotherapy (NAC). Methods The expressions of Apollon, Her-2, estrogen
receptor (ER) and progesterone receptor (PR) were detected immunohistochemically in biopsy tissues from 124 breast cancer
patients. The clinical responses to NAC were evaluated in line with the response evaluation criteria in solid tumors (RECIST).
The pCR rate was analyzed for different types of breast cancer. The correlations between Apollon status with Her-2, ER, PR,
lymph node status and tumor size were analyzed. Immunohistochemistry was used to compared the changes in Apollon
expression in the breast cancer tissues before and after NAC. Results The pCR rate was 18.5% (23/124) in these patients.
Negative expressions of apollon, ER and PR were all associated with a higher pCR rate after NAC. Apollon was significantly
correlated with Her-2, ER, PR and lymph node involvement. Chemotherapy significantly down-regulated apollon expression
in the tumor cells. Conclusion Anegative apollon expression might be a predictor of pCR in patients with breast cancer.