Clinical relevance of p53 index and expression of proliferating cell nuclear antigen and Ki-67 in gastric cancer

The prognostic value of the immunohistochemical expression of p53 protein, proliferating-cell nuclear antigen (PCNA) and Ki-67 antigen was evaluated in a series of 116 stage I–II gastric cancer patients. The staining for p53 protein (staining frequency and intensity) in malignant cells was expressed as a p53 index. Similarly, the staining frequency and intensity for PCNA and Ki-67 were evaluated. The p53 index was independent of the stage and differentiation grade, but significantly related to DNA ploidy, S-phase fraction and mitotic activity. A high p53 index was a sign of inferior survival, compared to a low or intermediate index. p53-negative tumours were also associated with poor survival. In a multivariate analysis, only the depth of tumour infiltration and the presence of nodal metastases were independent prognostic factors in stage I–II gastric cancer. PCNA expression and Ki-67 antigen expression were not related to the stage, ploidy, proliferative activity or p53 expression, and they had no impact on survival. The results indicate that p53 protein expression may be of prognostic significance in gastric cancer, while PCNA and Ki-67 antigen expression have no predictive value.