C-myc amplification and cluster analysis in human gastric carcinoma.

The tumour samples ot 23 patients (9 male, 14 female, aged 28-85) were randomly selected for the study. DNA was isolated from paraffin embedded tissue for quantitative dot-blot hybridization, in order to determine the amplification values for the c-myc and K-ras oncogenes. The clinical and histological parameters studied were as follows: grade, TNM staging system, Lauren's histological type, localization and the severity of the disease. Amplified c-myc was found in 6 cases. Amplification was concomitant with c-myc overexpression detected with immunohistochemical staining. The amplification--9.1-fold on the average (ranging from 2.12 to 18.2) was significantly associated with the presence of distant metastasis (corr. coeff.: 0.5623, p < 0.01), but with none of the other parameters. No case with K-ras amplification was recorded. The result of the multivariate cluster analysis proved that age was the decisive factor in the segregation process. This age-related distribution (69 vs. 40, p < 0.001), however, did not coincide with either the incidence of distant metastasis or c-myc amplification.