[303] Molecular Apocrine Breast Carcinomas (MAC) Develop Brain Metastases (BM) Early with Respect to the Appearance of Systemic Metastases (SM)

X Song, K Hengel, AS Braverman, G Sidhu, YD Kim, J Weedon, X Li, CA Axiotis. Kings County Medical Center, Brooklyn, NY; SUNY Downstate Medical Center, Brooklyn, NY; Case Western Reserve University, Cleveland, OH

Background: BM often occur late in BC patients, and usually follow prolonged pharmacologic therapy of SM. Breast cancer (BC) classification by gene expression profiling has identified aggressive BC phenotypes. Human epidermal growth receptor-2 (HER2) positive tumors have a high incidence of BM. The phenotypes of tumors of BC patients who develop BM early relative to the appearance of SM have not been thoroughly examined. The identification of such phenotypes would allow for early detection or preventive measures and the development of selective therapies.
Design: We identified 55 cases of BC with BM from 1993-2007 which had clinical follow-up information and pathologic material available for review. All cases were evaluated for tumor type, Elston grade, and HER2 status. HER2 was tested by immunohistochemical staining (IHC), and HER2 fluorescence in-situ hybridization analysis (FISH) was conducted on all IHC 2+ cases. Estrogen receptor (ER) (49/55) were tested by IHC. All cases with > 75 % apocrine histology were tested for androgen receptor (AR) by IHC. The BC patients were divided into two groups: Group1) Those in whom SM developed prior to BM (n=24; Group 2) Those who had only BM, or whose SM developed at the time of, or after BM (n=31). Data analysis used Fisher's exact test for categorical variables.
Results: All BC were invasive; morphology was ductal not otherwise specified (IDC-NOS) (n=46), apocrine (n=7), colloid (n=1), lobular (n=1). Thirteen of the IDC-NOS cases were grade II (13/46) and 33 were grade III (33/46). All apocrine carcinomas were grade III. BC were considered MAC if they had >75% apocrine histology and were AR+/ER-. MAC represent 13% (7/55) of all our cases as compared to 1-2% of all IDC cases. All of the MAC patients were HER2+ and were in group 2 (vide supra) with respect to BM and SM occurrence, p=0.01. None of the SM of the 7 MAC patients occurred before their BM; 3 had only BM, while the SM of the remaining 4 patients were diagnosed at the time of or after the occurrence of BM.
Conclusions: We conclude that the incidence of MAC tumors may be increased in BC patients with BM, and that MAC patients developed BM early with respect to the occurrence of SM.
Category: Breast

Monday, March 9, 2009 1:00 PM

Poster Session II # 45, Monday Afternoon