Analytical bias by contamination from hemolysis in determination of serum lactate dehydrogenase isoenzyme 1 in patients with testis germ cell tumors

Laboratory markers and germ cell tumors

The International Germ Cell Consensus Classification (IGCCC) of testicular germ cell tumors (TGCT) in 1997 included three serum tumor markers, serum lactate dehydrogenase catalytic concentration (S-LD), serum alpha fetoprotein concentration (S-AFP), and serum human chorionic gonadotropin concentration (S-hCG). The recommendation should be implemented for all patients with TGCT and is also useful for patients with ovarian and extragonadal germ cell tumors. A fourth serum tumor marker for TGCT, S-LD isoenzyme 1 (S-LD-1), is also relevant for TGCT. Patients with seminoma have a raised S-LD-1 more often than a raised S-AFP and S-hCG, whereas patients with nonseminoma have a raised S-AFP more often than a raised S-LD-1 and S-hCG. A new model combining IGCCC and S-LD-1 predicts survival better than previous staging systems. LD-1 is related to a characteristic chromosomal abnormality in all types of TGCT, a high copy number of chromosome 12p. In contrast, AFP and hCG are found mainly in nonseminomatous germ cell tumors and they related to the histologic differentiation of the tumors. The different biologic background for the serum tumor markers may contribute to the difference in their clinical behavior.

A systematic review of lactate dehydrogenase isoenzyme 1 and germ cell tumors

OBJECTIVES

To evaluate lactate dehydrogenase isoenzyme 1 (LD-1) as a tumor marker of germ cell tumors.

METHODS

A literature search included a CancerLit and Medline computer search of articles regarding germ cell tumors and LD-1 published between 1963 to 99 and a manual search of reference lists, theses, and textbooks. Forty articles, letters to the editor, and abstracts on testicular germ cell tumors and 10 articles on ovarian germ cell tumors fulfilled inclusion criteria.

RESULTS

Of 696 patients with testicular germ cell tumors, 423 (61%) had a raised serum LD-1 catalytic concentration (S-LD-1). Patients with seminoma have a raised S-LD-1 more often (63%) than those with nonseminoma (60%). S-LD-1 was raised less often in patients with stage I (48%) than in those with stage II (50%) and stage III (67%). S-LD-1, serum alpha fetoprotein concentration (S-AFP), and serum human chorionic gonadotropin concentration (S-hCG) were discordant. S-LD-1 predicted outcome in four studies: one study regarding relapse in patients with nonseminomatous testicular germ cell tumors stage I, and three studies regarding survival of patients with metastatic testicular germ cell tumors. In two of three studies, S-LD-1 was a better prognostic predictor for patients with metastatic testicular germ cell tumors than S-LD. Of 40 patients with ovarian germ cell tumors, thirty-five (88%) had a raised S-LD-1.

CONCLUSIONS

S-LD-1 is a useful serum tumor marker of testicular germ cell tumors. For patients with ovarian germ cell tumors, S-LD-1 was raised more often than for patients with testicular germ cell tumors. Further studies are required for a general recommendation regarding the use of S-LD-1 for germ cell tumors.

Analytical quality specifications for serum lactate dehydrogenase isoenzyme 1 based on clinical goals

The aim of the study was to deduce analytical quality specifications for the determination of catalytic concentration of serum lactate dehydrogenase isoenzyme 1 (S-LD-1) according to clinical goals (the clinical utility model). We defined clinical goals for false positive and false negative S-LD-1 measurements in the monitoring of patients with testicular germ cell tumors (TGCT), clinical stage I, on a surveillance only program. The absolute S-LD-1 catalytic concentrations were routinely corrected for contamination from preanalytical hemolysis. A reference group of 37 men had a near In-Gaussian distribution for the absolute S-LD-1 catalytic concentration. The geometric mean was 76 U/l and an S-LD-1 >128 U/l (99.72 percentile, the decision limit) indicated a high risk of a relapse of TGCT. We have previously shown that an S-LD-1 >160 U/l (treatment limit) was associated with a suboptimal outcome from the treatment of metastatic TGCT. The maximum allowable analytical positive bias was 5 U/l, and the maximum allowable analytical negative bias was -32 U/l. The maximum allowable analytical coefficient of variation, CV(A), was 11% (approximately 14 U/l) at a bias = -5 U/l. For S-LD-1 measurements not corrected for hemolysis, the decision limit was 145 U/l, the maximum allowable negative bias -19 U/l, and CV(A) 8%(approximately 12 U/l). A routine correction for hemolysis had a large impact on the analytical quality specifications.

Serum lactate dehydrogenase isoenzyme 1 as predictor of tumor-associated death in patients with testicular germ cell tumours

Serum lactate dehydrogenase iso-enzyme 1 (S-LD-1) was determined in 24 patients with testicular germ cell tumours who died during follow-up. Serum samples were obtained at the start of chemotherapy or late into the clinical course for those without evidence of a tumour. Seven of the eight patients with tumour-associated death had S-LD-1 > 150 U l-1 (median 260 U l-1 range 90-905 U l-1, as did two of the six who died without evidence of a tumour (median 134 U l-1 range 89-128 U l-1) (P = 0.03, Mann-Whitney U-test, two-tailed). The remaining 10 patients had previously been reported as to prediction of S-LD-1 for the prognosis, and were evaluated only as to the reproducibility of the S-LD-1 determination. S-LD-1 was determined in two serum samples obtained concomitantly from eight of these 10 patients: the difference between the two S-LD-1 determinations was median 6% of the average of the two S-LD-1 determinations (25-75% range 3-17%). Our study showed an unforeseeable high level of imprecision of the assay system. Nevertheless, S-LD-1 determinations in the regular monitoring of patients with testicular germ cell tumours may be useful for predicting tumour-associated deaths.

Serum lactate dehydrogenase isoenzyme 1. An early indicator of relapse in patients with testicular germ cell tumors

The present study aimed to evaluate serum lactate dehydrogenase isoenzyme 1 (S-LD-1) as an indicator of relapse for patients with testicular germ cell tumors. Twenty-seven patients were investigated with repeated determinations of S-LD-1 from diagnosis to relapse; 9 had seminoma and 18 nonseminomatous tumors. Eleven of 21 had raised S-LD-1 at relapse (4 with seminoma). Seven of the 27 patients had a raised S-LD-1 for median 2 months (1.4-4.5 months) before relapse was detected. Thus, S-LD-1 is of use, complementary to clinical examinations, determinations of serum alpha fetoprotein and human chorionic gonadotropin, and CT scans, in monitoring patients with testicular germ cell tumors for relapse.