Increased activity in serum of an alkaline phosphatase isoenzyme in cancer: analytical method and preliminary clinical studies.

Serum of cancer patients often contains high activities of a homoarginine-sensitive isoenzyme of alkaline phosphatase with high electrophoretic mobility, which is present in relatively low activities in sera from most normal persons and persons with benign disease. In earlier studies of this isoenzyme, in a semi-quantitative assay, electrophoresis was used in the separation step. This report describes a column separation procedure, which provides quantitative data. We tested the revised procedure by assaying a mixed panel of 192 sera (cancer, benign disease, and normal). The organ sites of cancer and benign disease in this study were: lung, pancreas, uterus, and ovaries. The isoenzyme showed moderate sensitivity for lung (0.6) and pancreas (0.8) cancer and high specificity for all cancers tested. Thus the assay may be useful for discriminating between cancer sera and non-cancer sera for these cancer types.