Histological type and syncytial growth pattern affect E-cadherin expression in a multifactorial analysis of a combined panel of sporadic and BRCA1-associated breast cancers.

E-cadherin is a prominent factor in maintaining the epithelial architecture, and loss of its normal function is considered to be a key element in cancer invasion. In breast cancer, correlation between alteration of E-cadherin expression and histological type has been reported, but associations with other parameters remain uncertain. To refine these findings and to explore the biological significance of features thought to result from alterations of cell-to-cell adhesion systems, rare in sporadic cases but more frequent in BRCA1-associated breast cancers (BRCA1-BCs), we investigated E-cadherin expression by immuno-histochemistry in a combined panel of 214 breast cancers enriched in hereditary cases (176 sporadic cases and 38 BRCA1-BCs). Following multivariate statistical analysis using a logistic regression model, only 2 parameters were significantly associated with loss of E-cadherin expression: lobular histological type (p < 0.0001), in agreement with previous results, and syncytial growth pattern (SGP) (p = 0.01). The latter result provides a biological basis for SGP, the cardinal feature of medullary breast carcinoma.