Colorectal ornithine decarboxylase activity in human mucosa and tumors: elevation of enzymatic activity in distal mucosa.

To examine the value of ornithine decarboxylase (ODC) assay as a biological marker of potential malignancy in large bowel, we harvested 43 colorectal carcinoma, 7 adenoma, 6 polyps, and 77 normal-appearing mucosa at surgery from patients with colorectal carcinoma. In addition, 13 normal rectal mucosa were obtained at biopsy from patients with benign diseases or diseases unrelated to colorectal carcinoma as normal control. ODC activity was significantly higher in polyps and adenocarcinomas than in normal-appearing mucosa from patients with colorectal carcinoma. ODC activity in normal-appearing mucosa varied throughout the large intestine, with significantly higher activities in the distal segment of the large bowel. The higher ODC activity detected in the sigmoid colon and rectum correlates with the larger incidence of tumor development in this region of the large bowel. This observation needs to be taken into consideration when ODC activities of the colorectal mucosa are measured as biological markers of potential malignancies.