Cytoplasmic ERß expression to predict efficacy and survival of EGFR-TKI in EGFR-mutant NSCLC.

e19067 Background: Estrogen receptor pathway has been reported to be interacted with epidermal growth factor receptor (EGFR) signal pathway. This study focused on the impact of intracellular ERβ localization (cytoplasmic or nuclear) on efficacy of EGFR-TKI. Methods: Tumor tissue specimens from 149 stage IV NSCLC patients treated with EGFR-TKI were analyzed using immunohistochemistry (IHC) for ER expression (ERα or β) and their associations with clinicopathological variables and clinical outcomes. Significance of cyto-ERβ expression was further examined in NSCLC cell lines. Results: The expression of ERα and ERβ was detected in 15% and 28.9% of the patients, respectively. Cyto-ERβ positive cases showed shortened PFS compared with negative ones (3.1 months vs. 7.3 months, p=0.061). In the EGFR-mutant subgroup, differences of PFS were enlarged with significant statistics (4.7 months vs. 10.9 months, p=0.042). COX’s proportional hazard model showed that female, EGFR mutation and c-ERβ status were independent ...