p53 null mutations detected by a p53 yeast functional assay predict a poor outcome in young esophageal carcinoma patients

Esophageal carcinoma is one of the most common gastrointestinal malignant neoplasms in the world. Recent advances in treatment modalities as well as surgical resection techniques have improved the changes of survival of patients with esophageal carcinoma, although the prognosis is worse than for the other gastrointestinal carcinomas. A more precise stratification beyond clinicopathological classification may help determine optimal treatment. The importance of p53 gene mutations in the pathogenesis of human esophageal carcinoma is well established, but it is still controversial whether the presence of p53 mutations adversely affects individual patient prognosis. In this study, we investigated the p53 mutations of esophageal carcinomas and their correlation with clinicopathologic factors. We employed a p53 yeast functional assay because it is highly sensitive and can detect mutations based on the actual function of the p53 gene, clarifying more precisely the role of this gene in esophageal carcinomas. We also studied young patients (≤65 years old), because our previous study raised the possibility of differences in the importances in esophageal carcinogenesis in young and old patients. Of 43 young esophageal carcinoma patients (42 squamous cell and 1 undifferentiated carcinoma), 38 (88.4%) harbored p53 mutations. Twenty-seven missense and 11 null mutations were detected, but the presence of p53 mutations did not correlate with any clinicopathologic factor. However, the null mutation was a significant indicator of a poor outcome (P=0.0278). All except one patient who harbored null mutation died within 3 years after a macroscopically curative resection. These data suggest that the type of p53 gene mutation may be predictive of outcome in young esophageal carcinoma patients. Furthermore, null mutations causing loss of function of the gene product may play a more important role than missense mutations in tumor progression.