Ki-67 immunoreactivity, ploidy and S-phase fraction as prognostic factors in patients with gastric carcinoma.

Expression of the Ki-67 antigen was determined by immunohistochemical analysis of paraffin-embedded specimens from 242 patients with gastric adenocarcinoma and the prognostic value of Ki-67 immunoreactivity was compared with ploidy and S-phase fraction (SPF) obtained by DNA flow cytometry. A high percentage of Ki-67 immunostaining was associated with the intestinal type of cancer (p = 0.0002) and male sex (p = 0.003), but correlated only weakly with the SPF (rs = 0.343) and not at all with ploidy. The intestinal type of gastric carcinoma was more frequently aneuploid and had a higher SPF than diploid tumours (p < 0.0001 for both). While the SPF was associated with male sex and stage of disease, both ploidy and SPF were associated with nodal status and age. There was no association between SPF or ploidy and tumour location or the presence of distant metastases. Both SPF and ploidy correlated with survival according to the univariate analysis. In a multivariate survival analysis, the stage of disease, DNA ploidy and presence of distant metastases emerged as independent prognostic parameters. There was no significant difference in survival between patients having tumours with high and low Ki-67 labelling, neither in univariate nor in multivariate survival analyses. In patients with gastric carcinoma, the level of Ki-67 immunoreactivity added no prognostic information to that obtained by DNA flow cytometry.