[130] Comparison of Tumor Biomarker Expression in Breast Cancer Patients before and after Neoadjuvant Chemotherapy.

Amber Cockburn, Yisheng Fang, Yan Peng, Barbara Haley, Venetia Sarode. University of Texas Southwestern, Dallas

Background: Tumor biomarker expression performed on core biopsies prior to neoadjuvant chemotherapy (NAC) is critical for planning treatment in patients with locally advanced breast cancer. In patients with significant residual disease, changes in biomarker expression after NAC may have prognostic and predictive significance.
The aim of this study is to compare biomarker (ER, PR, HER2, Ki67 and p53) expression in breast cancer patients before and after chemotherapy.
Design: Patients with locally advanced breast cancer who received NAC from 2000-2009 were identified at our institution and retrospectively analyzed. Tumor biomarkers were performed on core biopsies prior to chemotherapy and repeated on the post-NAC definitive surgical specimen. Analysis of biomarkers was performed in a routine fashion using standard immunohistochemical techniques and analyzed by a computer assisted image analysis. All HER2 borderline and positive (3+) immunohistochemical cases were confirmed by FISH analysis. The change in biomarker expression was compared to a control group who did not receive chemotherapy and had biomarker results on both core and excision specimens. Differences in expression in the two groups were analyzed.
Results: A total of 203 patients who received NAC were identified, of which 173 had complete data sets. Thirty-eight (22%) patients achieved pathologic complete response while 135 (78%) had residual tumor. The control group consisted of 51 patients. Results of biomarker expression in the NAC treated group showed significant change in ER, PR, HER2, and Ki67.

Neoadjuvant Chemotherapy Group
 No ChangeChange (pos-neg/neg-pos)P Value
ER +69110.027
ER -541 
PR +42150.02
PR -698 
HER2 +2513<0.0001
HER2 -916 
Ki67 >15%81260.009
Ki67 <15%1314 
p53 >10%417NS
p53 <10%745 

Except for p53, the control group exhibited no significant change in biomarker expression.

Control group
 No ChangeChange (pos-neg/neg-pos)P Value
ER +430NS
ER -81 
PR +335NS
PR -103 
HER2 +10NS
HER2 -491 
Ki67 >15%209NS
Ki67 <15%175 
p53 >10%780.001
p53 <10%333 

Conclusions: Neoadjuvant chemotherapy significantly alters tumor biomarker expression; therefore they should be repeated on the definitive specimens for further management of these patients.
Category: Breast

Tuesday, March 1, 2011 11:45 AM

Platform Session: Section C, Tuesday Morning


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