GENETIC CHANGES IN INTRADUCTAL BREAST-CANCER DETECTED BY COMPARATIVE GENOMIC HYBRIDIZATION

Ductal carcinoma in situ (DCIS) is considered a direct precursor of in vasive ductal breast cancer (IDC). We combined tissue microdissection and comparative genomic hybridization to identify genetic changes in f ive DCIS lesions with no invasion and in two that were adjacent to IDC . Extensive genetic changes characterized pure DCIS cases with gains o f 1q, 6q, 8q, and Xq as well as losses of 17P and chromosome 22 being most often involved. Except for the Xq gain, these changes are also co mmon to IDC. Separate analysis of DCIS and IDC components in the same tumor revealed all almost identical pattern of genetic changes in one case, whereas substantial differences were found in another. We conclu de that many of the common genetic changes in IDC may take place befor e development of invasive growth. However, a simple linear progression model may not always account for the DCIS-IDC transition.