Amplification of c-erbB-2 and aggressive human breast tumors?

well as allelic deletions ofgenes on chromosomes 11 or 13 (9, 10). The frequency and level of amplification of c-myc and c-erbB-2 proto-oncogenes vary between different groups of patients studied by different laboratories. Amplification of c-erbB-2 was reported in 10, 16, 18, and 40% of breast tumors from different groups of patients (2, 5-8). In one study this proto-oncogene was suggested as a "prognostic factor" (5) and in another as an "imperfect guide" (7) for aggressive breast tumors. We explored the relation between the copy number of the c-erbB-2 proto-oncogene and biological characteristics of primary human breast tumors collected at the Centre Rene Huguenin, St. Cloud, France (8). A 2to 40-fold increase in c-erbB-2 (chromosome 17q) was identified in 12 out of 122 tumor DNAs. In contrast, the presence of a normal copy number of the gene encoding the tumor antigen p53 (chromo-