Assessment of tumor cell kinetics by monoclonal antibody Ki-67

The expression of Ki-67 antigen in 71 patients with advanced gastric cancer was studied by immunohistochemical technique. Immunohistochemical staining with Ki-67 produced clear labeling of a portion of tumor cell nuclei, and the nucleoli stained intensely. The Ki-67 labeling rates of the 71 specimens ranged from 7.7 to 70.5% (mean: 29.2%; standard deviation: 12.9%). There was no significant association between Ki-67 labeling rates and macroscopic type, peritoneal metastasis, or serosal invasion. The tumors showing high Ki-67 labeling rates (greater than 25%) are more likely to have liver metastasis and lymph node involvement. Larger tumors, with a diameter greater than 6 cm, more frequently showed high Ki-67 labelling rate than those with a diameter less than 6 cm. When the Ki-67 labeling rate and 9 clinicopathologic parameters, as conventional prognostic factors, were entered simultaneously into the regression model, nodal status and Ki-67 labeling rate emerged as independent prognostic factors. These results indicate that the in situ determination of the growth fraction by Ki-67 antibody may be a reliable prognostic marker of advanced gastric cancer.