1) In Yoshida (ascites) sarcoma implanted rats, there was almost no change in succinic dehydrogenase activity until 3 days after implantation, then a marked decrease was noted, which continued until they died of the disease after about 10 days.
2) A “succinic dehydrogenase reducing substance” which, when injected into the peritoneal cavity of experimental animals would reduce the heart succinic dehydrogenase activity, could easily be demonstrated in the urines of patients with cancer and sarcoma, independent of their site, but not in cases of benign diseases.
3) This substance was missed often in the urines of patients with malignant diseases who had undergone to vigorous irradiation treatment.
4) The urine extracts of very small malignant tumor, showed no decrease of the heart succinic dehydrogenase activity.
5) In a few cases of leukemia, especially acute ones, the urine extracts revealed the decrease of the heart succinic dehydrogenase activity, when injected into mice.
6) The succinic dehydrogenase reducing factor is stable for 30 days in room temperature as powder, heatresistant by testing at 100°C for 30 minutes, non-soluble in alcohol-ether mixture, non-dialysable, destroyed by strong X-ray irradiation, but resistant to ultra-violet treatment.