Gastric cancer heterogeneity

This study was carried out on 222 samples from 37 gastric carcinomas to assess the incidence of multiple stem lines in primary tumors and metastasis as reflected by multiple DNA stem lines and their relationship to epidermal growth factor (EGF) receptor expression, histologic grade, tumor size, and degree of wall infiltration. Fifteen primary tumors (40.5%) were homogeneously diploid/peridiploid whereas 22 (59.5%) were aneuploid. In the lymph node metastasis, seven patients (29.2%) had an homogeneous diploid/peridiploid pattern in all metastatic lymph nodes. On the other hand, 17 (70.8%) had at least one aneuploid peak in the lymph node metastasis. DNA content heterogeneity was seen in 12 (33%) of primary tumors whereas 14 (66.6%) of 21 patients had multiple cell clones in the metastasis. Therefore, 12 patients had a metastatic clone which was not observed in the primary tumor. DNA content heterogeneity was seen even in tumors with submucosal invasion suggesting that this phenomenon is also present at earlier stages. No correlation between the histologic grade and the DNA distribution was observed. Furthermore, histologic heterogeneity was independent of DNA content heterogeneity. The EGF receptor expression was observed in six of the 23 patients in whom this analysis was done. The EGF receptor expression was constant in all samples which were studied and even samples with a different DNA content and histologic grade were stables for the EGF receptor expression.