ANALYSIS OF C-MYC AMPLIFICATION BY THE DIFFERENTIAL POLYMERASE CHAIN-REACTION (D-PCR), STUDY IN BREAST-CANCER

c-myc proto-oncogene amplification seems to have a prognostic value in breast cancer. In this study, quantitative analysis of c-myc amplific ation was carried out by differential polymerase chain reaction techni que (d-PCR) using beta-globin as the reference gene. d-PCR assessment showed coampIification products of c-myc and beta-globin depend on var iations in reaction factors such as the genomic DNA concentration, the relative concentrations of the various amplimers, the thermostable DN A polymerase concentration and the number of cycles. However, amplific ation of c-myc can be estimated quantitatively. In addition, results o f individual sets of d-PCR can be expressed on a standard reference sc ale. A clinical study of 309 patients with breast cancer found c-myc a mplification, respectively in 19% (45/236) of primary tumour tissues, 21% (4/19) of subsequent second primary cancers, 36% (4/11) of tumours of patients with bilateral lesions, 40% (8/20) of local recurrence tu mours and 22% (5/23) of metastatic lesions. Amplification of c-myc was observed more frequently in histological grades 2-3 (p<0.02), in ER n egative (p<0.01) and PgR negative tumours (p<0.02), but was not associ ated with age, tumour size, nodal status, histology, cytosolic catheps in D or pS2. d-PCR appears amenable to automation and should facilitat e large scale, inter laboratory gene amplification studies.