In summary, we have studied the amplification frequencies of HER2, C-MYC, CCND1 and FGFR1 in a 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 carcinoma. This evidence concerns the gene ERBB2 and ductal breast carcinoma in situ.