The expression pattern of members of the EGFR signaling pathway and its relation with the duration of response in metastatic breast cancer (BC) patients (pts) treated with endocrine therapy (ET)

3170 Background: Several lines of evidence suggest that EGFR, Her-2 and their downstream effectors Akt and MAPK are associated with endocrine resistance in BC. We investigated the expression pattern of these molecules and its relation with duration of response in metastatic BC pts treated with ET. Methods: The expression of EGFR, Her-2, pAkt, pMAPK were evaluated in tumor(tm) specimens from 44 BC pts who were treated with tamoxifen(T) or aromatase inhibitors (AIs) as first-line metastatic therapy. Her-3 and Her-4 were evaluated only in those cases with pAkt or pMAPK expression. The pts were stratified into 2 groups; A:those who progressed early (best response is PD ≤6mo of treatment), B:those who progressed late (PR or SD lasting ≥12 mo). Results: The median age of pts who received T/AIs was 45/55. The median duration of response to T-AIs was 2–3 mo/20–32 mo for pt groups A/B respectively. 22 pts progressed early on T/AIs(n=10/12), while 22 pts progressed late on T/AIs (n=9/13). EGFR,Her-2,pMAPK,pAkt were...