Decreased serum aldolase B levels in patients with malignant tumors

Serum aldolase B levels were determined in patients with malignant tumors using a radioimmunoassay method. Thirty-one of 52 patients with malignant tumors had decreased serum aldolase B levels of less than 20 ng/ml, whereas almost all of the normal subjects and the patients with liver diseases and other benign diseases showed serum aldolase B levels of more than 20 ng/ml. The decreased aldolase B levels observed in cancer patients were unrelated to the clinical stage of their disease. The decrease of aldolase B correlated well with the decrease of fructose-1-phosphate (F1P)-aldolase activity, but not with fructose-1,6-diphosphate (FDP)-aldolase activity in the sera of cancer patients. Mixing experiments did not identify an inhibitor of aldolase B in sera of cancer patients. Furthermore, recovery of serum aldolase B levels after successful surgical resection in cancer patients suggested that the low levels of aldolase B in sera of cancer patients was not of genetic origin. The mechanism responsible for the decrease of aldolase B in sera of cancer patients is unclear.