Sequential estimation of alkaline phosphatase isoenzymes (API) in breast cancer patients.

Different serum API from 83 breast cancer patients were separated by acrylamide gel electrophoresis. Their quantities were calculated in regard to enzyme-kinetically measured total AP activity by means of densitometry. The mean total activity in patients with bone or bone and liver metastases was twice as high as in 54 patients without any evident metastases. This increase of total activity was caused by an increase of bone and liver isoenzyme activity. Sequential determination of isoenzyme activities showed a good correlation between the clinically apparent course of the disease and changes of enzyme activity.