Study on Ki-67 Immunoreactivity as a Prognostic Indicator in Patients with Advanced Gastric Cancer

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Abstract
Background: Cell proliferation characteristics may reflect the aggressiveness of gastric tumors and their eventual prognosis. The aim of this study was to evaluate whether the proliferative activities determined by the antibody Ki-67 could be used as a prognostic predictor in patients affected by advanced gastric cancer. Methods: The prognostic significance of proliferative activity was investigated in 56 patients who underwent curative gastrectomy (R0) for advanced gastric cancer using the monoclonal antibody Ki-67. The patients were divided into three groups according to the Ki-67 labeling index of the tumors: 40% (17 cases). The Cox regression model was used to evaluate the prognostic significance of the Ki-67 index controlling for age, gender, histology, depth of tumor invasion and node metastasis. Results: There was no significant relationship between the Ki-67 index and wall invasion (P = 0.80) or nodal status (P = 0.73). The cumulative 3-year survival rates (95% Cl) were 61.0% (35.3–79.2%) in patients with Ki-67 index 40% and the differences were not statistically significant (P = 0.93). Also in multivariate analysis the proliferative activity did not independently affect survival (P = 0.98). An interaction between Ki-67 index and age was found and Ki-67 index >40% was significantly associated with a poor prognosis in patients over 68 years old (P = 0.004). Conclusion: Our study indicated that the proliferative activity in gastric cancer, determined with the monoclonal antibody Ki-67, does not influence the survival except in elderly patients (>68 years old).