Response to neo-adjuvant exemestane in post-menopausal breast cancer patients: correlation with biological factors measured by real-time quantitative RT-PCR (QRT-PCR)

538 Background: The effects of aromatase inhibitors on tumor biological factors in the neo-adjuvant setting are still not well documented and predictive factors of response are needed in addition to hormone receptor status. Methods: 41 postmenopausal women with estrogen and/or progesterone receptor (ER, PR) positive operable breast cancer received neoadjuvant exemestane 25 mg once daily, during 16 weeks. Frozen and formalin-fixed tumor tissues were collected before treatment and at surgery for pathological and biological markers measured by immunohistochemistry (IHC) and QRT-PCR. We analyzed ERα, PgR, Ki67, HER2 at the protein and mRNA level (IHC and QRT-PCR) and ERβ, aromatase and COX-2 (QRT-PCR). Results: QRT-PCR was performed on pre-treatment biopsies in 31 cases. The median quantity of total RNA was 4,5 μg (range: 0.3–22,7). For each target gene, median and range mRNA values relative to the TBP reference gene were : ERα : 306 (48–893) ; ERβ: 34.6 (3.5–278.5) ; PgR: 263 (2–2738) ; Ki67: 18.5 (3.3–66.5)...