Tumor host relations. VI. Is alpha-ketoglutarate a tumor marker? Association with tumor extent in humans--correlation with tumor size in rats.

A 4-year survey is presented on the alpha-ketoglutarate (KG) values in whole blood of 200 patients with malignant neoplasms mainly of the gastrointestinal tract and the female breast. A group of patients with benign surgical diseases served as control. KG showed an association with the extent of the primary tumor classified according to the TNM-scheme. The percentages of single values above the 2s-range of the control were as follows: T2: 18%,T3: 41%, and T4: 64%. The mean value of KG had highly significantly increased already in stage T2 as compared to the control group. Rats bearing the Yoshida sarcoma showed a significant correlation between the tumor size and the daily excretion of KG into urine during the early stage of tumor growth. The results suggested that KG cannot be regarded as an early tumor marker in humans, but may be of some value as an aid for the differential diagnosis in advanced tumor stages.