Invasive Breast Carcinomas in Ghana: Higher Frequency of High Grade Tumors with Squamous Differentiation, Triple Negative Status, and EZH2 Expression
Judy Pang, Kathy Toy, Kent Griffith, Lisa Newman, Celina Kleer. University of Michigan, Ann Arbor, MI
Background: Breast cancer in African American women is frequently ER negative, high grade, and more aggressive than in Caucasian women. The ancestors of most African American women come from West Africa, including Ghana. The Polycomb group protein enhancer of zeste homologue 2 (EZH2) is a marker of poor outcome in Caucasian breast cancers. This study investigates the histologic features, expression of ER, PR, HER-2/neu, and EZH2 in Ghanian breast cancers.
Design: Benign and malignant breast tissue from women treated at Komfo Anoyke Teaching Hospital between 2006 and 2011 were obtained for histologic classification. Immunostains for ER, PR, and HER-2/neu were performed previously. EZH2 immunostain was performed following the manufacturer's protocol. EZH2 nuclear expression was scored on a 0-3 scale: no staining (0), staining in <50% of cells (1), moderate staining in >50% (2), and strong staining in >50% (3). Cytoplasmic staining was noted as present or absent.
Results: 100 invasive carcinomas and 69 benign biopsies were studied. Of the invasive carcinomas, 89 were ductal, 2 were lobular, and 9 were metaplastic. Squamous differentiation was seen in 11% (6 metaplastics and 5 ductals with squamous features). The majority of carcinomas were grade 3 (52%), 41% were grade 2, and 7% were grade 1. Most were negative for ER (76%), PR (77%), and HER-2/neu (87%). 62% were negative for all three. EZH2 was significantly expressed in malignant compared with benign breast (p<0.0001). EZH2 expression was significantly associated with high histologic grade (p<0.05). Greater EZH2 expression was seen in ER negative (26%) than ER positive tumors (4%), although not statistically significant. 16% of invasive carcinomas showed cytoplasmic staining which was significantly associated with ER negative and triple negative status (p<0.05).
Conclusions: Invasive carcinomas in Ghanian women are frequently poorly differentiated with squamous features. Invasive lobular carcinomas are rare. Most invasive carcinomas are triple negative. Similar to Caucasian tumors, EZH2 expression is associated with high histologic grade. In a subset of invasive carcinomas, EZH2 is localized to the cytoplasm, which has not been previously reported and warrants further investigation. Our data provide first histologic and biomarker characterization of Ghanian breast cancers which is necessary to develop more efficacious treatments and useful prognosticators.
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 29, Wednesday Afternoon