DNA aneuploidy and high proliferative activity but not K-ras-2 mutations as independent predictors of clinical outcome in operable gastric carcinoma: Results of a 5-year Gruppo Oncologico dell'Italia Meridionale (GOIM) prospective study

Abstract

BACKGROUND. The prognostic value of DNA ploidy, S-phase fraction (SPF) and K-ras-2 mutations in gastric carcinoma (GC) has not yet been clearly defined. The aim of this study was to clarify the association between biomolecular variables, tumor characteristics, and clinical outcome in GC patients. METHODS. Resected specimens from a consecutive series of 69 patients with GC who underwent potentially curative surgery were studied prospectively. DNA ploidy and SPF were assessed by flow cytometry on multiple frozen tumor samples, whereas K-ras-2 mutations were detected by polymerase chain reaction followed by single-strand conformation polymorphism. All the patients involved in this study were followed up for a mean of 95 months. RESULTS. DNA aneuploidy was present in 72% of the cases (50 of 69), whereas 10% of these (5 out of 50) showed multiclonality. Mutations of K-ras-2 were detected in 8% of the tumors (5 of 63). Both DNA ploidy and SPF were associated with TNM stage (American Joint Committee on Cancer [AJCC] staging system) and node status. Moreover, DNA aneuploidy was significantly related to high SPF. K-ras-2 mutations were not associated with clinicopathologic variables or flow cytometric indicators. At univariate analysis, advanced TNM stage, node involvement, diffuse histotype, depth of invasion, DNA aneuploidy, and high SPF proved to be significantly related to quicker tumor relapse and to shorter overall patient survival. With multivariate analysis, DNA aneuploidy, high SPF, and depth of invasion were related to risk of tumor relapse and patient death, whereas diffuse histotype was independently related to patient risk of tumor relapse. CONCLUSIONS. DNA ploidy and SPF, when associated with clinicopathologic staging, might be useful for the identification of GC patients who have different risks for death or relapse of disease. © 2001 American Cancer Society.