MAINTENANCE OF DNA CONTENT AND ERBB-2 ALTERATIONS IN INTRADUCTAL AND INVASIVE PHASES OF MAMMARY-CANCER

Ductal carcinoma in situ (intraductal carcinoma) of the breast is a co mmonly recognized and curable clinical entity. Patients with intraduct al carcinoma are at risk to develop invasive breast cancer presumably due to a transition from the noninvasive to the invasive phase of grow th. Primary breast malignancies commonly display both in situ and inva sive phases of growth in the same tumor. In the current study, DNA con tent and alterations in the erbB-2 (HER-2/neu) oncogene product were e xamined simultaneously in both growth phases of primary breast cancers by image analysis. DNA content in the intraductal and invasive compon ents of primary breast cancers were virtually identical (r = 0.979, p < 0.001). Quantitative image analysis was used to measure erbB-2 expre ssion and categories of expression were related to copy number of the erbB-2 gene. Expression of erbB-2 was similar in both growth phases an d implies identity of the erbB-2 genotype. The identity of DNA content suggests that the noninvasive and invasive phases within a single bre ast cancer are highly related. It is likely that erbB-2 gene number re mains the same during progression from intraductal to invasive disease .