Flow cytometric DNA analysis of carcinoid tumors of the ileum and appendix.

Although all carcinoid tumors are considered potentially malignant, the biologic behaviors of appendiceal and ileal carcinoids are distinctly different. Appendiceal carcinoids often behave in a benign fashion, whereas ileal carcinoids pursue an aggressive course with frequent metastasis. Whether differences in DNA ploidy are related to this disparity in tumor behavior was addressed in this study. Flow cytometric DNA analyses were performed on paraffin blocks from 11 ileal and seven appendiceal carcinoid tumor cases. The mean coefficient of variation for all samples was 3.4 +/- 0.7. DNA aneuploidy was seen in two of the appendiceal cases and in six of the ileal cases. Metastases were seen in one of the appendiceal carcinoid cases, and that tumor was aneuploid. In six cases of carcinoid of the ileum, metastases were seen; of these, five tumors were aneuploid. In the ileal cases, despite the low number of cases examined, the correlation between DNA aneuploidy and metastases nearly reached statistical significance (P = .07) and showed a much stronger correlation than tumor size and metastases (P = .4). Although no statistical significance was reached in this study, the results are highly suggestive of DNA aneuploidy being an important predictor of malignant behavior in carcinoids of the ileum.