Increased activity in serum of alkaline phosphatase isoenzyme in cancer. Analytical method and preliminary clinical studies. Clin Chem 22

Serum of cancer patients often contains high activities of a homoarginine-sensitive isoenzyme of alkaline phos-phatase with high electrophoretic mobility, which is present in relatively low activities in sera from most normal persons and persons with benigndisease. In earlier studies of this isoenzyme, in a semi-quantitative assay, electro-phoresis was used in the separation step. This report de-scribes a column separation procedure, which provides quantitative data. We tested the revised procedure by assaying a mixed panel of 192 sera (cancer, benign dis-ease, and normal). The organ sites of cancer and benign disease in this study were: lung, pancreas, uterus, and ovaries. The isoenzyr1e 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. We reported the appearance in serum of an electrophoret-ically fast, homoarginine-sensitive isoenzyme of alkaline phosphatase (EC 3.1.3.1; FHAP) that bears a relationship to the presence of cancer (1). In the initial studies, we used an electrophoretic separation technique and a semiquantitative assay procedure which were described in detail (2). A procedure for the column-chromatographic separation of FHAP was described earlier (3). High FHAP values for presumably normal persons, which varied with total alkaline phosphatase concentration, led us to conclude that FHAP was incompletely separated from other serum alkaline phospha-tase activity. Here, we describe an improved column separa-tion procedure, together with an analysis of the FHAP activity in a mixed panel of cancer and non-cancer sera provided in a blind manner by the Mayo Clinic Serum Bank