Flow-cytometric DNA content analysis of esophageal squamous cell carcinomas

To better understand the mechanisms of esophageal carcinogenesis, abnormalities in DNA content of esophageal squamous cell carcinomas were studied. Cellular DNA content was determined by flow cytometric study of 70 endoscopic biopsy specimens obtained from 26 patients with esophageal squamous carcinoma. High-quality histograms were obtained for 23 patients. Twenty-one patients had at least one aneuploid population in their tumor. In 7 patients, multiple aneuploid peaks were detected. Specimens from 2 patients were diploid. The interpretation of the DNA histograms was difficult in 3 patients; an aneuploid population of cells was probable in 2 of them. A statistically significant relationship was found between the degree of differentiation and DNA content abnormalities in the regions of the tumors that could be evaluated by endoscopic biopsies: well-differentiated carcinomas had diploid or small aneuploid populations containing less than 15% of the cells, whereas DNA histograms of moderately or poorly differentiated carcinomas were characterized by large aneuploid peaks representing 25%-90% of the cells and a higher proliferative fraction. No relationship was found between the size or the stage of the tumor and the DNA content detected in endoscopic biopsy samples. The frequency and the multiplicity of abnormal clones in esophageal squamous carcinomas indicates that this cancer, like esophageal adenocarcinoma, develops an association with an acquired genomic instability that produces abnormal clones of cells, according to the multistep model of neoplastic progression.