Serum enzymes in patients with carcinoma of lung: lactic-acid dehydrogenase, phosphohexose isomerase, alkaline phosphatase and glutamic oxaloacetic transaminase.

Serial determinations of serum lactic-acid dehydrogenase (LDH), phosphohexose isomerase (PHI), alkaline phosphatase (AP), and glutamic oxaloacetic transaminase (GOT) were carried out in 30 patients with primary and four with secondary neoplasms of the lung. Enzyme values were correlated with the stage of illness, with tumour histology, with chemotherapy and with the extent and site of metastases as determined at autopsy. The activity of the enzymes LDH and PHI was most frequently elevated; their values correlated closely. AP and GOT tended to become elevated only shortly before death. Although, in general, enzyme activity increased with tumour extension and often in relation to chemotherapy, assays provided little assistance in early diagnosis or prognosis except that, in most instances, elevated values of any of the four enzymes indicated the presence of metastases.