Although primary malignant neoplasms of the duodenum have been recognized as rare for many years, this condition has not been clarified yet.
On the assumption of existence of anti-tumor activities in the duodenum, Brunner's glands as an anatomical singularity, the following results were obtained experimentally. 1) The possibility of Brown-Pearce tumor-take in the duodenum of rabbits was less as compared with in the other gastrointestinal canal, and an intimate relation was observed histologically between Brunner's glands and tumor growth in the duodenal wall. 2) The secreting fluid of Brunner's glands played a suppressive role on the growing of cultured tumor tissue in the incubated eggs. 3) The fluid showed anti-tumor activity on the Ehrlich mouse ascites carcinoma. 4) The fluid had an inhibitory action on the growing of Brown-Pearce tumor in the eyes or testicles of rabbits. 5) The anti-tumor activities presented by the secreting fluid of Brunner's glands were completely inactivated by heating the fluid at 100°C. for five minutes. The secreting fluid of the stomach had no such anti-tumor activities.