Evaluation of DNA-Ploidy Heterogeneity in Gastric Cancers

Prognostic value of DNA-ploidy in gastric cancers is still a matter of controversy. A possible explanation for the discrepant results reported in the literature could be sampling error in tumours with multiple stemlines differing in DNA-ploidy [2,4]. In order to determine whether or not such hetero-geneity exists and play a role in biology of gastric cancers we have analysed two different types of gastric carcinoma; the early gastric carcinoma (EGC) and the advanced gastric carcinoma (AGC). We have performed DNA-ploidy analysis on multiple samples providing from a group of 17 EGC of which 8 were pure intramucosal and 9 were infiltrating into the sub-mucosa. Then we have analysed 16 AGC, according to the same procedure. We found an aneuploid DNA-stemline in 8 EGC (47%) more often in tumours invading into the sub-mucosa (5/9) than in pure mucosal tumours (3/8). Multiple DNA-stemlines were found more frequently in submucosal infiltrating tumours (4/5) [3]. From the 16 AGC cases, 15 revealed DNA-aneu-ploid with heterogeneity in 4 cases (26%). In conclusion we have reported that 53% of EGC were diploid compared to only 6% of AGC. Hetero-geneity was found in 13% intramucosal EGC, 44% in submucosal EGC and 26% of AGC [1]. These results are consistent with the hypothesis of stepwise ploidy progression: from diploid in most EGC to aneuploid but heterogeneous in infiltrating EGC to aneuploid but homogeneous in AGC. This is in agreement with the notion that the development of a single aneuploid, more aggressive, cell clone is a crucial mechanism in the progression from early to advanced gastric cancer. DNA-ploidy in advanced gastric carcinoma is less heterogeneous than in early gastric cancer, Cell. Early gastric carci-noma with focal advanced cancer: a particular subtype of gastric carcinoma, Hum.