Abstract P3-01-03: The Predictive Value of Serum Serum Her-2/neu for Response to Anthracycline-Based and Trastuzumab-Based Neoadjuvant Chemotherapy of Advanced Primary Breast Cancer

Abstract

Abstract Background:There excists little information about a possible influence of serum Her-2/neu on response to chemotherapy. We aimed that the assessment of serum Her-2/neu in pretreatment serum sample can be useful in predicting response to neoadjuvant chemotherapy. Methods: All breast cancers were tested by immunohistochemical stain and FISH for Her-2/neu before treatment. Serum Her-2/neu was twice measured by Chemiluminescence immunoassay (ADVIA centaur®TMsystem) before neoadjuvant chemotherapy and before operation. The cutoff value was 10.2 mg/ml according to previous study. Pathologic complete response (pCR) was considered as no residual tumor or remnant ductal carcinoma in situ, partial response (PR) was less than 50% decrease in maximal diameter in pathologic tumor size.The measurements for the change of serum Her-2/neu were defined as pretreatment Her-2/neu — preoperation Her-2/neu. We compared the change of serum Her-2/neu between 1) before prechemotherapy and after chemotherapy 2) pathologic complete response and partial response 3) trastuzumab (H) group and anthracyline (A) group. Results: Serum Her-2/neu was decreased after neoadjuvant chemotherapy. Mean of serum Her-2/neu in prechemotherapy was 15.4±9.0 ng/mL, that of postchemotherapy was 10.5± 2.0 ng/mL (p= 0.04). Pathologic response was correlated with the change of serum Her-2/neu (PR: 6.1 ng/ml vs. pCR: 42.0 ng/ml, p= 0.014). Serum Her-2/neu of trastuzumab group was more decreased than of anthracyline group (H=12.9 ± 14.5 ng/mL ; A= 2.2 ± 1.2 ng/mL; p=0.024). In trastuzumab group, pCR was boreline significantly correlated with change of serum Her-2/neu (PR: 0.8 ± 0.84 ng/ml vs. pCR: 21.1 ± 13.2 ng/ml, p= 0.08). Conclusions: Prechemotherapy serum Her-2/neu was to be a significant predictor of pathologic response to neoadjuvant chemotherapy. Serum Her-2/neu levels during treatment were associated with pathologic response in patients receiving neoadjuvant chemotherapy, particularly, in trastuzumab-based regimen. Serum Her-2/neu levels may serve to monitoring neoadjuvant therapy in Her-2/neu overexpressed breast cancer. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-01-03.