[210] Loss of Retinoblastoma (RB) Tumor Suppressor Expression in Breast Cancer Correlates with Better Response to Neoadjuvant Chemotherapy

Jeanne M McFalls, Jessica Kline, Gordon F Schwartz, Agnieszka K Witkiewicz. Thomas Jefferson University, Philadelphia, PA

Background: Neoadjuvant chemotherapy followed by surgery is standard of care for locally advanced breast cancer. However, breast cancers show a wide variation in response to neoadjuvant chemotherapy, with some achieving complete pathologic remission while others continue to progress unabated. The aim of this study was to investigate whether expression of the retinoblastoma tumor suppressor (RB), p16, estrogen receptor (ER), progesterone receptor (PR), and HER2, in pre-treatment breast cancers predicts their response to neoadjuvant chemotherapy.
Design: We retrospectively reviewed the medical records and pathology of 130 patients with breast cancer who were treated with neoadjuvant chemotherapy followed by surgical excision at our institution from 1982 to 2010. Patients for whom no tissue was available prior to neoadjuvant treatment were excluded (33 patients). Pretreatment tissue was stained with antibodies against ER, PR, Her2, RB, and p16. Medical records were reviewed for pre-treatment tumor size and stage. Post-surgical excision pathology slides were reviewed and response to neoadjuvant therapy was graded using complete pathologic remission (cPR), modified Miller-Payne score, and clinical-pathologic stage (CPS) scoring systems.
Results: RB loss was seen in 16.6% of ER positive and in 60% of triple negative breast cancers. Loss of RB significantly predicted an improved response to neoadjuvant chemotherapy, as measured by complete pathologic resistance, modified Miller-Payne score, and CPS score (p value < 0.01 for all three measures).
Conclusions: Loss of RB tumor suppressor staining in pre-treatment breast cancer biopsies can be used prior to initiation of neoadjuvant chemotherapy to predict good tumor response. Patients whose tumors express RB may benefit from proceeding directly to surgical excision.
Category: Breast

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 15, Monday Morning


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