Evaluation of numerical abnormalities of chromosomes 1 and 17 in proliferative epithelial breast lesions using fluorescence in situ hybridization.

Our aim was to investigate the putative role of chromosome abnormalities of chromosomes 1 and 17 in the process of breast carcinogenesis. Numerical abnormalities of chromosomes 1 and 17 were investigated using fluorescence in situ hybridisation (FISH) in a series of 16 primary invasive breast carcinomas associated with intraductal proliferative epithelial lesions. Chromosome 1 aneusomy was detected in 55.6% of ductal hyperplasia (DH), 81.8% of ductal carcinomas in situ (DCIS) and 87.5% of invasive ductal carcinomas (IDC). Chromosome 17 aneusomy was not detected in the cases of DH and was present in 90.9% of DCIS and in 87.5% of IDC. Simultaneous aneusomy of chromosome 1 and 17 was found in 81.8% of DCIS and in 75.0% of IDC. Our results showed that the number of chromosome 1 and 17 copies increases from normal epithelium to invasive cancer. The numerical abnormalities of chromosome 1 were already detected in DH, suggesting that a gain in the copy number of chromosome 1 may be involved early in breast carcinogenesis.