The influence of carcinoma growth on diamine oxidase activity in human gastrointestinal tract.

The distribution of diamine oxidase (DAO) activity was studied in patients having no carcinoma disease. Besides in gut DAO occurred in high activity only in kidney and mesenteric lymph nodes. In patients with adenocarcinoma of the large bowel or of the stomach the enzymic activity was reduced in the tumour tissue itself as compared with the adjacent mucosa in which part the highest activities were observed. In stomach it seemed most important that the enzymic activity was enhanced in the whole mucosa, also in a 10 cm distance from tumour where no histological alterations were found. This fact should be checked for significance in early tumour diagnosis.