Intratumoral heterogeneity in DNA ploidy of esophageal squamous cell carcinomas.

Intratumoral heterogeneity in DNA ploidy was investigated in 23 cases of squamous cell carcinoma of the esophagus. Nuclear DNA content was determined for multiple samples taken from the same tumor, using a flow cytometric technique. The incidence of DNA aneuploidy was 87% in this series, and DNA indices ranged from 0.78 to 2.64 but most of them fell within values between 1 and 2. Of these cases ten (43.5%) showed intratumoral heterogeneity in DNA ploidy; in addition to a diploid population, one to four heterogeneous aneuploid subpopulations were discernible in the same tumor. However, morphologic variation was minimal within the same tumor. DNA index seen in metastatic lesions was identical with one of those in the primary lesion. Mechanisms responsible for intratumoral difference in DNA ploidy are also discussed from the aspect of tumor progression.