Lingle, WL

Abstract Abstract #56 Background: Recent findings from NSABP B-31 suggested that breast cancer (BC) patients (pts) with c-MYC (MYC)/HER2 co-amplification in their primary tumors may benefit more in terms of disease-free survival (DFS) from adjuvant trastuzumab (n=471; p<0.0001, HR 0.24; 13 vs. 51 events) than those pts with only HER2 amplification in their primary tumors (n=1078, p=0.007, HR 0.63; 55 vs. 82 events).
 Purpose: The overall objective of this analysis is to determine the association between MYC/HER2 co-amplification and outcome of pts randomized to receive chemotherapy alone (Arm A) or chemotherapy with concurrent trastuzumab (Arm C) on N9831.
 Patients/Methods: This analysis included 868 pts from the HER2+ NCCTG N9831 Intergroup adjuvant trastuzumab phase III clinical trial on Arms A or C. Fluorescent in situ hybridization (FISH) was performed at a central laboratory, Mayo Clinic Clinical Cytogenetics Laboratory, using dual probe mixtures for HER2 (17q11.2-12/centromere 17) and for MYC (8q24/centromere 8). The HER2 amplification status in whole tissue sections was evaluated to determine eligibility of pts for N9831. Tissue microarrays containing three cores from each patient's tumor were analyzed for MYC amplification status. The gene and centromere copy number as well as the distribution of the signals for each marker were determined in sixty non-overlapping interphase nuclei.
 Results: Of 273 pts with completed FISH analyses, 34 (12%) pts had MYC amplification. The rate of MYC amplification was similar across arms (18/135 [13%] vs. 16/138 [12%]; ChiS p=0.66). Co-amplification of MYC/HER2 was observed in 32 (12%) pts with similar co-amplification rates across arms (17/135 [13%] vs. 15/138 [11%]; ChiS p=0.66). Based on preliminary analyses, MYC amplification and MYC/HER2 co-amplification do not appear to be associated with race, menopausal status, hormone receptor status, nodal status, tumor histology, tumor grade, or tumor size (all ChiS p>0.05); however, MYC amplified pts were significantly younger than MYC non-amplified pts (mean 46.4 vs. 51.0, t-test p=0.02) and MYC/HER2 co-amplified pts were significantly younger than MYC/HER2 non-co-amplified pts (mean 45.9 vs. 51.0, t-test p=0.01).
 Conclusions: In our initial analyses of 239 pts, we observed a lower frequency of MYC/HER2 co-amplification than the previously reported 30% for NSABP B-31. Complete FISH analyses of 868 pts in N9831 and association with DFS will be presented. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 56.

Abstract Abstract #4037 Background: Mammographic breast density is a strong and consistent risk factor for breast cancer. Women with dense tissue in over 60 to 75% of the breast are at 4 to 6 times greater risk than women with little or no density. However, the biology of breast density is not well understood and studies at the tissue level are limited. We present the first report of a tissue-based study of breast density, sampling mammographically dense and non-dense areas of the breast of healthy women with the goal of examining histologic correlates.
 Materials and Methods: Healthy women volunteers aged 40 to 85 years, with no breast symptoms, normal screening mammogram within 6 months, and no personal history of breast cancer were considered eligible. Women with breast-related symptoms, those on endocrine therapy, or with bleeding tendencies were excluded from participation. Sixty consecutive eligible women were enrolled in the study- results are based on the first 34 participants. Eligible women underwent an ultrasound-guided, core-needle breast biopsy of mammographically dense and non-dense areas of the breast, performed by a single experienced radiologist. Quantitative assessment of breast tissue from dense and non-dense areas was performed for epithelium, stroma, and fat. In addition, we assessed the difference in the extent of lobular involution (complete, partial and none) between dense and non-dense areas. We used means and SD to describe distributions in each tissue type. Signed rank test was used to assess within woman differences between dense and non-dense tissue.
 Results: The mean age of the participants was 50.1 years (range 40 to 79 years). The histological findings are outlined below.
 
 Dense tissue is comprised of increased stroma and epithelium and decreased fat, consistent with prior reports on breast density. The finding of 'no involution' was greater in dense tissue compared to non-dense tissue (24% versus 8.8%); non-dense tissue had greater proportion of complete involution compared to dense tissue (82.5% versus 35.2%).
 Discussion: This report is the first to quantify histology in tissue sampled from dense and non-dense regions of the healthy breast. We find a dramatic difference in tissue composition between dense and non-dense tissue in the breast. Future studies using this tissue to assess molecular markers will further help to characterize pathways through which density may increase breast cancer risk. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4037.

Abstract Abstract #4033 Background: Aromatase activity within the breast is a source of estrogen that may cause breast cancer. Mammographic density (MD) is a risk factor for breast cancer whose biologic basis is unknown. Our study compared aromatase expression in tissue from dense and non-dense areas of the breasts of healthy volunteers.
 Methods: Participants were 40+ yrs, had a screening mammogram with visible MD, no history of cancer and were not on endocrine therapy. Ultrasound-guided core biopsies were done within 6 months of mammography to obtain three paired cores from mammographically dense and non-dense regions of the breast. Immunostaining for aromatase expression employed the streptavidin-biotin amplification method using the recently developed 677 mouse monoclonal antibody. Immunoreactivity (IR) was scored in terms of proportion of cells staining positive for aromatase (PPC) (0=<1%, 1=1-25%, 2=26-50%, 3=51+% (and 4=75%+ for adipocytes)) and relative immunointensity (0=none, 1=weak, 2=moderate, 3=intense) for each cell type (stroma, normal ductal epithelium, adipocytes). A composite score weighting the PPC by their relative intensity (range 0-9; 0-12 for adipocytes) was also calculated. The sum of the composite score across the three cell types provided a global assessment of aromatase IR. Repeated measures analyses evaluated differences in aromatase IR for dense compared to non-dense tissue within and across cell types. Parameter estimates (β) indicated the average difference between dense and non-dense IR.
 Results: 18 (37%) of the 49 participants were premenopausal (median age 46 yrs). Summing across cell types, the global composite score showed increased aromatase IR on sections sampled from dense vs. non-dense regions (β=5.3,p<0.001). This global difference reflected increased aromatase IR in the stroma and normal ductal epithelium from dense sections (vs. non-dense). For 42 women with >1% stromal cells on each section, there was evidence for increased IR on dense sections as indicated by the greater PPCs (β=0.9), relative intensity (β=0.7) and composite score (β=2.7)(p's<0.001). Similarly, for 20 women with >1% normal ductal epithelium in both dense and non-dense sections, there was a greater composite score (β=1.4,p=0.004) for cells on dense sections although differences for PPC (β=0.3,p=0.11) and relative intensity (β=0.3,p=0.09) did not reach statistical significance. No differences were seen in IR for adipocytes from the two density regions (46 women). Findings were unchanged with adjustment for covariates, including proportions of each cell type per section.
 Conclusions: There is strong evidence for increased aromatase expression in the stromal and normal ductal epithelium of dense vs. non-dense tissue. These results support ongoing research into mammographic density as a biomarker of effect of aromatase inhibitors. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4033.