EXPRESSION OF C-ERB B-2 PROTEIN AND DNA-PLOIDY IN BREAST CARCINOGENESIS

Objective.-to examine the c-erb B-2 expression and nuclear DNA content in samples of breast lesions to ascertain any relationship between c- erb B-2 expression and aneuploidy in the different types of proliferat ive breast lesions and in intraductal and invasive carcinomas. Design and Setting.-lmmunohistochemical analysis of c-erb B-2 expression and cytometric nuclear DNA assessment were performed in a series of 39 cas es of intraductal hyperplasia without atypia, 7 cases of intraductal h yperplasia with atypia, 64 cases of intraductal carcinoma, and 85 case s of invasive breast carcinoma (30 of which had extensive intraductal component). Results.-Overexpression of c-erb B-2 was seen only in case s of carcinoma: 28 (43.7%) intraductal carcinomas and 15 (17.6%) invas ive carcinomas. Aneuploidy was demonstrated in 3 (43.0%) cases of intr aductal hyperplasia with atypia, in 54 (84.4%) cases of intraductal ca rcinoma, and in 63 (74.2%) cases of invasive carcinoma. All cases of i ntraductal hyperplasia without atypia were euploid and none expressed c-erb B-2. Among the carcinomas (intraductal and invasive) there was a strong relationship between aneuploidy and c-erb B-2 expression. In m ost instances, the intraductal and invasive components of the 30 invas ive carcinomas with extensive intraductal component displayed similar DNA content and c-erb B-2 immunoreactivity; whenever there was a diffe rence, the intraductal component tended to be aneuploid (five out of s ix cases) and c-erb B-2 positive (one case), in contrast to the respec tive invasive component. Conclusions.-The higher frequency of aneuploi dy and c-erb B-2 expression in intraductal carcinomas in comparison wi th invasive carcinomas suggests there is not a linear relationship bet ween DNA content abnormalities and neoplastic progression and that som e invasive breast carcinomas evolve without an identifiable intraducta l phase or are unrelated to disturbances at the c-erb B-2 locus.