Abstract P1-11-11: Correlation between ER/PgR/Her-2/Ki67 Expression and Response to Neoadjuvant Endocrine Therapy for HR Positive Post-Menopausal Breast Cancer

Abstract

Abstract Background: Endocrine therapy was standard adjuvant treatment for hormone receptor positive breast cancer. However, there were factors other than receptor status could influence endocrine responsiveness. Neoadjuvant therapy was an excellent platform for predictive factors research, but the standard for evaluating the efficacy of neoadjuvant endocrine therapy was controversy. The aim of this study was to investigate the correlation among the results of different response evaluation system, and the relationships between ER/PgR/Her-2/Ki67 expression and the responses to neoadjuvant endocrine therapy for postmenopausal breast cancer. Methods: Data of consecutive 133 core needle biopsy (CNB) confirmed hormone receptor strongly positive (more than 50% tumor cell stained ER or PgR) postmenopausal breast cancer treated with neoadjuvant endocrine therapy were analysis retrospectively. All pts. were planned to receive endocrine therapy alone as their adjuvant treatment and prescribed Anastrozole 1 mg per day for 16 weeks before surgery. Clinical response were evaluated by using documented ultrasound records,pathological response was evaluated by one senior pathologist with Miller & Payne classification. Cell cycle complete response was defined as post-treatment Ki67 ≥1%. The new slides of pre-treatment and surgical specimens were made for ER/PgR (ER\PR DakoCytomation)/Her-2 (Her-2 Dako HercepTest TM)/Ki67 (Ki67 Ventana) immunohistochemical staining through Benchmark XT Staining Instrument (Ventana Medical Systems. Inc. Arizona. USA) and classified by using image analysis system Ariol (Applied Imaging Inc., San-Jose, California, USA). Results: Clinical response were CR:0.8% PR:33.1% SD:66.1%, pathological response were G5:3% G4+G3:47.4% G2+G1:49.6%, Ki67 change were <1%: 22.8% decrease but >1%:45.1% no decrease: 32.1%. The correlation and consistency among the response evaluated differently were poor [table 1]. The per-treatment ER/PR/Her-2/Ki67 showed low degree of correlation with responses [table 2]. Pre-treatment ER≥90% and PR≥90% and Her-2 coudln't predict better response. The correlation and consistency among response evaluated in different system Conclusion: The correlation and consistency among the results of response to neoadjuvant endocrine therapy evaluated by different system were poor. ER/PgR/Her-2/Ki67 showed low degree of correlation to responses. It's difficult to predict response to Arimidex neoadjuvant endocrine therapy by using ER/PgR/Her-2/Ki67 expression. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-11-11.