Are bilateral breast cancers different from breast cancers coexisting with ovarian cancer? An immunohistochemical analysis aimed at intrinsic tumor phenotype.

Bilateral breast cancers (BBC) and breast cancers coexisting with ovarian cancer (BOCS) are associated with genetic predisposition more frequently than sporadic cases. We compared the phenotypes of these tumors to better understand their pathomechanisms and aid the guiding of their clinical management.,Tumor morphology and expression of ER, PgR, HER2, Ki67, CK5/6, E-cadherin, vimentin and EGFR were assessed in a tissue microarray containing cores from 174 BBC, 23 BOCS and 2 BBC + BOCS.,BOCS tumors were characterized by higher incidence of EGFR expression, HER2 negativity and lower incidence of intraductal component. HER2-positive phenotypes were marginally more frequent in the BBC group and triple negative tumors - in BOCS.,Breast cancers from BOCS patients are characterized by more aggressive phenotype, most probably related to their more frequent association with BRCA1 mutation.