P2-11-09: EGFR Overexpression in Triple Negative Breast Cancer (TNBC) and Its Association with the Prognosis.

Abstract

Abstract Objective: The aim of this study is to investigate EGFR expression in Triple Negative Breast Cancer (TNBC), and to find the relationship between EGFR overexpression and prognosis of TNBC, further to clarify the significance of EGFR in TNBC and provide valuable information for TNBC therapy. Methods: 42 triple ***negandection ***ssitive breast cancer patients(studying group) and 40 HER2(3+) breast cancer patients(controling group) who underwent surgery from January 2000 to December 2005 were analyzed. 82 cases of paraffin-embedded specimens were detected by Immunohistochemistry(IHC), fluorescence in situ hybridization(FISH) and polymerase chain reaction(PCR) to investigate the overexpression, amplification and mutation of EGFR gene. The distant-free survival(DFS) and overall survival(OS) of these patients were used to investigate the relationship between EGFR overexpression and the prognosis of TNBC. Results: 34(43.9%) EGFR overexpression was observed in all cases, while gene amplification was only 7(9.1%) cases. No EGFR gene mutation was found in all cases. Overexpression of EGFR occurring in 57.1% patients in TNBC group and 25.0% patients in HER2 group, and we didn't found any correlation between EGFR overexpression and clinicopathology. 50(61.0%) patients relapsed (TNBC 28,HER2 22) and 27(32.9%) patients died(TNBC 18,HER2 9) were observed during the more than 5 years follow-up. The 5-year DFS was 57.1% and 77.5% respectively, the 5-year OS was 71.4% and 87.5% in TNBC and HER2 groups. In TNBC group, the survival of the EGFR-overexpressing group patients was significantly lower than that of the non-EGFR-overexpressing group patients (p=0.018 for DFS, p=0.026 for OS); In HER2 group, no statistical difference was found (p=0.079 for DFS, p=0.055 for OS). Conclusions: This study showed that EGFR overexpression increased significantly in TNBC patients, which was no correlation with their clinico-pathological data. EGFR gene amplification was much less frequent than its overexpression. It suggested that EGFR gene amplification may not be the unique mechanism of EGFR overexpression in TNBC. There may be other possible mechanisms and pathways that cause EGFR overexpression. In addition, it may suggest that gefitinib therapy is useless in TNBC patients because we did not find any mutations in the tested exons of TNBC. EGFR overexpression may associate with a poor outcome of TNBC patients which suggest it could be a significant prognostic factor for TNBC patients. EGFR may play important role for molecular-targeting therapy of TNBC. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-11-09.