Flow cytometric quantitation of the proliferation-associated nuclear antigen p105 and DNA content in advanced gastric cancers.

Flow cytometric quantitation of the proliferation-associated nuclear antigen p105 was done on cancer cell suspensions from 114 advanced gastric cancers and correlated with clinical behavior. DNA diploidy was observed in 45 (39.5%) and aneuploidy in 69 (60.5%) cases. By setting the cutoff line at the level used in a negative control study without primary antibody in the same sample, the p105-labeling rate was calculated by the p105-DNA dual fluorescence analysis. The mean p105-labeling rate was 37.7% (range, 9.3% to 79.0%). The p105-labeling rates were significantly higher (P less than 0.05) for aneuploid DNA, liver metastasis, vascular invasion, and histologically well-differentiated tumors. The 5-year survival rate of patients with high p105-labeling tumors (p105-labeling rate, greater than 30%) was significantly poorer (P less than 0.01) than that of patients with low-labeling tumors. When the p105-labeling rate and the clinicopathologic parameters were entered simultaneously into the Cox regression model, the stage of disease, DNA ploidy, p105-labeling rate, and vascular invasion emerged as independent prognostic parameters. These findings indicate that the measurement of p105 may provide useful information for predicting prognosis in advanced gastric cancers.