P2-11-07: Expression of Selected Predictive Markers in African American Women with Atypical Hyperplasia of the Breast.

Invasive breast carcinoma in African American (AA) women differs significantly from their Caucasian (CA) counterparts in its incidence, morphology and outcome. These tumors are more likely to be high grade, hormone receptor negative, present at a younger age and at a higher stage. Evaluation and a better understanding of precursor lesions may help delineate the mechanisms underlying the development of breast cancer in these two groups. Atypical hyperplasia (AH) in the breast has been associated with an increased risk of developing cancer (relative risk∼4.0). Risk stratification of these women by identification of predictive biomarkers would be beneficial for optimal patient care. In our study we evaluated the expression of the following prognostic biomarkers: estrogen receptor (ER), Cyclooxygenase-2 (COX-2) enzyme and Ki-67 in AH in a cohort of AA women with benign breast biopsies. AA women with benign breast biopsies from years 1997–2000 were retrieved from our departmental database. Clinical and follow up data was obtained from the SEER database. The hematoxylin and eosin (H & E) slides for these cases were reviewed by 2 pathologists, who were blinded to the outcome, and those with atypia were included in this study. Paraffin blocks were retrieved for immunohistochemical (IHC) analysis and standardized scoring methods applied. A total of 1608 AA women had benign breast biopsies during the study period. We performed IHC analysis on 37 (2.3%) who were diagnosed with atypia (25 cases of atypical ductal hyperplasia (ADH) and 12 cases of atypical lobular hyperplasia (ALH)). Increased COX-2 expression was seen in 19 of 28 (67.8%) cases with AH. Of these, 13 of 19 cases (68.4%) were of ADH and 6 of 9 cases (66.7%) were of ALH. Twenty of 25 cases had a high expression of ER overall. Of these, 15 of17 (88.2%) of the positive cases was in the ADH category and 3 of 7 (42.8%) was in the ALH group. Of 32 cases, only 3 cases showed a proliferation rate of > 2% (9.4%) with Ki-67 IHC stain. All of these cases belonged to the ADH (21) category. In summary, the majority of AH cases showed increased COX-2 expression, although no differences were observed between lobular and ductal lesions. In contrast, ADH lesions appeared to exhibit increased reactivity for ER compared to ALH. Similarly, although rare, more ADH cases showed an increased proliferation rate compared to ALH. From our data, COX-2 and ER might be of prognostic significance in AA patients with AH. Larger studies with follow up are needed to understand this disease further. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-11-07.