Measurement of high molecular weight forms of enzymes in serum in the detection of hepatic metastases of colorectal cancer.

Total gamma-glutamyl transferase and alkaline phosphatase, liver-specific alkaline phosphatase and high molecular weight forms of the two enzymes were measured in the sera of 42 patients with colorectal cancer, of whom 26 were apparently metastases-free and 16 had palpable liver metastases. The average levels of all enzymes were significantly higher in the group with metastases, but there was considerable overlap between the groups. The predictive values of positive results were of the order of 50-75%; predictive values of negative results were more than 70% for all tests, with high molecular weight alkaline phosphatase (87%) performing best in this respect. However, measurement of high molecular weight enzymes does not offer marked advantages over more conventional enzyme tests in the detection of hepatic metastases of colorectal cancer.