Abstract 3451: Breast cancer risk factor associations by loss of E-cadherin tumor tissue expression: A pooled analysis of 5,896 cases in 12 studies from the Breast Cancer Association Consortium (BCAC)
Authors: Horne Hisani N. , Oh Hannah , Sherman Mark E. , Palakal Maya , Hewitt Stephen H. , Schmidt Marjanka , Benitez Javier , Milne Roger , Brenner Hermann , Nevanlinna Heli , Mannermaa Arto , Chenevix-Trench Georgia , Couch Fergus , Devilee Peter , Eccles Diana , Hooning Maartje , Swerdlow Anthony J. , Orr Nick , Troester Melissa A. , Cora Renata , Pharoah Paul D. , Garcia-Closas Montserrat , Figueroa Jonine D. 
Published: July 2016

Abstract
Purpose: Expression of the tumor suppressor gene E-cadherin is diminished in lobular breast cancers and has been implicated in epithelial mesenchymal transition. We assessed risk factor associations for breast cancer stratified by low vs. high E-cadherin protein expression in a pooled analysis within the Breast Cancer Association Consortium (BCAC) studies.
Methods: E-cadherin tumor tissue staining was performed centrally at the NCI on formalin-fixed paraffin-embedded tissue microarray (TMA) sections representing 6,010 breast cancer patients from 12 US and European BCAC studies. TMAs were digitally scanned and scored using the SlidePath Digital Image Hub (Leica Biosystems, Wetzlar, Germany). For 5,896 cancers with evaluable tumors, E-cadherin was visually scored as estimated percent of positive cells times stain intensity (0, 1+, 2+, 3+) (score range 0-300). E-cadherin low was defined as tumors with a score &lt; 100. Risk factor associations for low vs. high E-cadherin expressing tumors were evaluated by logistic regression, adjusted for age and study site, and stratified by ER status and histologic subtype. To assess the consistency in results by study, meta-analyses were performed using the random-effects model. All statistical tests were two-sided.
Results: E-cadherin low cancers comprised 20% of tumors and were associated with lobular histology, well/moderately differentiated cancers, &gt; 2cm in size, and HER2-negative status (χ2, P &lt; 0.003 for all factors). E-cadherin low status was associated with family history of breast cancer (FH) (OR = 1.32, 95% CI = 1.09-1.60, P-het = 0.005) and ever use of menopausal hormones (OR = 1.26, 95% CI = 1.02-1.56, P-het = 0.03). Study specific meta-plots showed consistent effects across studies for menopausal hormone therapy (I2 = 0.0%, p = 0.64); however, E-cadherin loss by FH did show evidence of heterogeneity by study (I2 = 54%, P = 0.03). Differences in E-cadherin expression remained significant for FH, and menopausal hormone use when further adjusted for ER (P &lt; 0.05). We also found relationships with E-cadherin loss to vary by BMI, number of live births, age at first birth, and oral contraceptive use in stratified analysis by ER status and histologic subtype.
Conclusion: This large pooled analysis shows that breast cancer risk factor associations may differ by E-cadherin expression independent of ER status, suggesting that it may represent a marker of etiologic heterogeneity.
Citation Format: Hisani N. Horne, Hannah Oh, Mark E. Sherman, Maya Palakal, Stephen H. Hewitt, Marjanka Schmidt, Javier Benitez, Roger Milne, Hermann Brenner, Heli Nevanlinna, Arto Mannermaa, Georgia Chenevix-Trench, Fergus Couch, Peter Devilee, Diana Eccles, Maartje Hooning, Anthony J. Swerdlow, Nick Orr, Melissa A. Troester, Renata Cora, Paul D. Pharoah, Montserrat Garcia-Closas, Jonine D. Figueroa. Breast cancer risk factor associations by loss of E-cadherin tumor tissue expression: A pooled analysis of 5,896 cases in 12 studies from the Breast Cancer Association Consortium (BCAC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3451.