An autoradiographic study on the labeling index of biopsy specimens from gastric cancers.

With the aim of examining proliferative activity of gastric cancers of various histologic types, H3-thymidine labeling indices of biopsy specimens from 48 patients were examined using an in vitro labeling technique. The results indicated that the indices were greatly variable (1.4-40.8%) from case to case and from area to area, and could not be well correlated with either gross findings, histologic types, or the degree of tumor invasion. However, the distribution of the labeled cells within the tumor was somewhat characteristic to each histologic type. In adenocarcinomas, DNA-synthesizing cells were scattered at random over the entire tumor tissue. In signet-ring cell carcinomas, small tumor cells with dark-staining cytoplasm were preferentially labeled. In contrast, typical signet-ring cells had practically zero labeling index, suggesting that they are out-of-cycle cells and are functionally differentiated.