ERBB2 and ductal breast carcinoma in situ: In this study, we compared the gene amplification frequencies of HER2, C-MYC, CCND1 and FGFR1 in a relatively large series of pure DCIS, DCIS associated with invasive carcinoma, and invasive carcinomas, to investigate the role of gene amplification in the progression of DCIS to invasive carcinomas.