Lactate dehydrogenase and its isoenzymes in testicular germ cell tumors: an overview.

Serum lactate dehydrogenase (S-LDH) was raised in 41 of 82 patients with testicular germ cell tumors, none of three with subclinical testicular tumors, and 10 of 341 without testicular germ cell tumors, 215 of whom had a previous history of tumor. 13 of 38 with testicular germ cell tumors, none of three with subclinical testicular germ cell tumors, and seven of 341 without tumor lesions had raised levels of isoenzyme S-LDH-1. 46 of 52 had concordant changes in S-LDH and total tumor volume whereas in six this relationship was not noted. Concordant changes in S-LDH-1 and total tumor volume were found in most cases. Higher S-LDH and S-LDH-1 levels were noted in the blood from the testicular vein on the side of the tumor at orchiectomy than in peripheral blood. The S-LDH activity predicted survival in a multivariate analysis of risk factors in 39 patients with stage 3 metastases from testicular germ cell tumors. 70-75% of 37 with tumor lesions had concordantly raised or normal S-LDH and serum concentrations of alphafetoprotein (S-AFP) and human chorionic gonadotropin (S-hCG); 25-30% had discordant levels. The diagnostic specificity of S-LDH and S-LDH-1 with regard to tumors in 252 with a history of testicular germ cell tumors was 68%, the diagnostic sensitivity 90%, the nosographic specificity 97%, the nosographic sensitivity 41% for S-LDH and 35% for S-LDH-1, and the effectiveness of the tests 88% for S-LDH and 90% for S-LDH-1. Tumor tissue from a testicular germ cell tumor transplanted into athymic mice had a high activity of LDH-1. There was a good correlation between S-LDH-1 and tumor volume. S-LDH may be used as a tumor marker in patients with testicular germ cell tumors in addition to other diagnostic tests. In patients with a history of testicular germ cell tumors and an unexplained elevation of S-LDH, raised S-LDH-1 may indicate the presence, and normal S-LDH-1 the absence, of testicular germ cell tumors.