Increased mucosal ornithine decarboxylase activity in large bowel with multiple tumors, adenocarcinoma, and adenoma.

The polyamine biosynthetase, ornithine decarboxylase (ODC), involved in tumor promotion, was investigated in grossly normal mucosa obtained from surgically resected large bowel; 48 cases with and six cases without large bowel cancer. The mucosal ODC activity was significantly higher in 17 multiple tumor cases bearing adenocarcinoma(s) plus adenoma(s) than in 31 solitary tumor cases bearing one adenocarcinoma alone. It was higher in the mucosa of the two groups of cases than in the mucosa of individuals without large bowel cancer. Furthermore, the enzyme activity in left-sided cancer cases was significantly higher than that in right-sided cancer cases. Carcinoma tissue showed a remarkable high level of enzyme activity, compared with the normal mucosa. The results indicate the larger the number of tumors the higher the level of the ODC activity in the normal mucosa, particularly in left-sided cancer cases. It is concluded that the mucosal ODC may provide a good biological marker to detect individuals at higher risk for large bowel cancer due to exogenous or endogenous factors, and thus contribute to the prevention of mortality from large bowel cancer.