Clonal Heterogeneity in Human Esophageal Squamous Cell Carcinomas on DNA Analysis

Cancers are thought to arise through multistep accumulation of somatic mutations in the progeny of a single cell. Multiple mutations may induce molecular intratumor heterogeneity. Therefore, we examined molecular clonal heterogeneity in esophageal squamous cell carcinomas. Twenty‐four esophageal squamous cell carcinomas and associated lymph node metastases were examined for microsatellite alterations, and abnormalities of the p53 and transforming growth factor‐β type II receptor (TGF‐β RII) genes. There were eight cases (33%) showing different patterns of loss of heterozygosity in primary tumors and metastatic lymph nodes with microsatellite markers. On the other hand, the abnormalities of p53 were identical in all these cases. No mutation was detected in the simple repeated sequences of the TGF‐β RII gene. These results indicate that molecular clonal heterogeneity exists in esophageal squamous cell carcinomas. Therefore, care is necessary in preoperative genetic diagnosis using biopsy samples.