Comparison of loss of heterozygosity and microsatellite instability in adenocarcinomas of the distal esophagus and proximal stomach

Adenocarcinoma of the gastroesophageal junction is rapidly rising in incide nce. It has been proposed that these tumors be classified as three differen t types: distal esophageal (AEG I), cardia (AEG II), and subcardia (AEG III ). Using comparative genomic hybridization (CGH) analysis, one recent study reported that the 14q chromosomal arm showed a significantly higher rate o f deletion in esophageal than In cardia adenocarcinoma. Using a microsatell ite analysis technique, we analyzed this area and regions in the vicinity o f the APC, DCC, and p53 genes. Tumor and normal tissues were microdissected from 54 cases (27 AEG I and 27 AEG III). DNA was extracted and then amplif ied using seven fluorescent-labeled microsatellite markers, one pair each o n 5q, 18q, and 17p and four on 14q. The results were analyzed for loss of h eterozygosity (LOH) and microsatellite instability (MSI). LOH varied from 2 0% to 30% at each locus except for the 17p locus, where it was slightly abo ve 50% in both groups. No significant differences in LOH or MSI were found between the esophageal and gastric tumors, including the 14q chromosomal ar m. These results fail to confirm the finding that abnormalities on the 14q chromosomal arm distinguish between distal esophageal and proximal gastric tumors.