The prognostic significance of proliferating cell nuclear antigen in clinical gastric cancer

Background. Proliferating cell nuclear antigen (PCNA) is an intranuclear protein that is closely linked to the cell cycle. This antigen can be detected in formalin-fixed specimens. We studied the expression of PCNA in primary gastric cancer to identify its significance as a prognostic factor. Methods. The avidin-biotin-peroxidase complex method was used for PCNA staining in sections from 138 patients with primary gastric cancer. All sections were formalin fixed and paraffin embedded. Two different sections were examined in each case. Results. The PCNA labeling index (PCNA-positive cells/1000 cells × 100) varied from 7.0% to 59.7%. There were significant differences in tumor size, morphologic type, depth of tumor invasion, lymphatic permeation, vascular permeation, and lymph node metastasis between the high (≥33.4) and low (<33.4) PCNA labeling index groups. The 5-year survival rates of the high and low PCNA labeling index groups were 5.8% and 66.2%, respectively, a significant difference (p < 0.001). Multivariate analysis showed that the PCNA labeling index was an independent prognostic factor for gastric cancer. Conclusions. Because PCNA immunostaining can be done in routine formalin-fixed paraffin-embedded sections, this could be a powerful tool for providing information about the prognosis of patients with gastric cancer.