Placental-type alkaline phosphatase in ovarian cancer fluids and tissues

Placental-type alkaline phosphatase was measured in sera, cyst, and ascites fluids, and from tumor extracts obtained from gynecologic cancer patients, particularly those with cancer of the ovary. A modified assay was used that depended on long incubation (20 to 24 hours) to measure the heat-stable, phenylalanine-sensitive placental isoenzyme. The concentration of enzyme in ascites and cyst fluids was markedly higher than in serum. Cyst fluid values were generally higher than ascites fluids from the same individual. The median enzyme levels for malignant cyst fluids were 50 times greater than for benign cyst fluids. When tumor tissue and fluids were available from the same patients, it was observed that the levels in each were proportional. Determination of this isoenzyme in serum did not give a useful index of tumor burden, as metastatic disease did not consistently result in elevated serum enzyme levels. When ovarian cancer patients were divided into two groups--those in whose sera placental-type phosphatase was elevated, and those in whom it was not--the presence of the enzyme in serum at the time of tumor diagnosis appeared to be a negative prognostic indicator, judged from survival data.