Serum lactate dehydrogenase isoenzyme 1 as a marker of testicular germ cell tumor

Serum Tumour Markers in Testicular Germ Cell Tumours: Frequencies of Elevated Levels and Extents of Marker Elevation Are Significantly Associated with Clinical Parameters and with Response to Treatment

Introduction

Although serum tumor markers beta human chorionic gonadotropin (bHCG), alpha-fetoprotein (AFP), and lactate dehydrogenase (LDH) are well-established tools for the management of testicular germ cell tumours (GCTs), there are only few data from contemporary cohorts of primary GCT patients regarding these biomarkers. Our aim was to evaluate marker elevations in testicular GCTs and to document their associations with various clinical characteristics.

Patients and Methods

A total of 422 consecutive patients with GCTs were retrospectively analysed regarding serum levels of bHCG, AFP, and LDH during the course of treatment. Additionally, the following characteristics were recorded: histology, age, laterality, clinical stage (CS), pT-stage, and tumour size. Marker elevations were first tabulated in dichotomized way (elevated: yes/no) in various subgroups and second as continuous measured serum values. Descriptive statistical methods were employed to look for differences among subgroups and for associations of elevations with clinical parameters.

Results

In all GCT patients, the frequencies of elevated levels of bHCG, AFP, LDH, and bHCG or AFP were 37.9%, 25.6%, 32.9%, and 47.6%; in pure seminomas 28%, 2.8%, 29.1%, and 30.3%; and in nonseminoma 53.0%, 60.1%, 38.7%, and 73.8%. Significant associations were noted with pT-stages >pT1, clinical stages >CS1, tumour size, and younger age. Frequencies of marker elevations dropped significantly after treatment, but LDH levels remained elevated in 30.5%-34.1%. Relapsing patients (n=27) had elevated levels of bHCG, AFP, and LDH in 25.9%, 22.2%, and 29.6%, respectively, thirteen of whom with a changed marker pattern.

Conclusions

The classical GCT-biomarkers correlate with treatment success. Clinical utility is limited due to proportions of < 50% of patients with elevated levels and the low specificity of LDH. The elevation rates are significantly associated with histology, clinical and pT-stages, tumour size, and younger age. Individual marker patterns may change upon relapse. Clinically, ideal biomarkers are yet to be found.

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.

Electrophoretic Variant of a Lactate Dehydrogenase Isoenzyme and Selective Promoter Methylation of the LDHA Gene in a Human Retinoblastoma Cell Line

Background: Lactate dehydrogenase (LD), a tetrameric product of the genes LDHA and LDHB, may be increased in sera of cancer patients. A variant isoenzyme with electrophoretic mobility between LD2 and LD3 (LD2ex) has been described in patients, but its molecular nature is largely unknown.

Methods: A newly established retinoblastoma cell line, NCC-RbC-51 (R51), showed an isoenzyme pattern with only two bands, LD1 and LD2ex. We investigated the isoenzymes by Northern blot, Western blot, and methylation analysis and PCR.

Results: Northern blot analysis revealed that R51 cells expressed no wild-type/somatic LDHA mRNA, but did express a small amount of LDHA-related mRNA with a slightly higher molecular mass. Western blot analysis confirmed the anti-LDHA-reactive protein with a 3-kDa higher molecular mass. Treatment of R51 cells with the demethylating agent 5-aza-2′-deoxycytidine restored the expression of the LD2, -3, -4, and -5 isoenzymes. PCR analysis of sodium bisulfite-treated genomic DNA revealed that the CpG island in the promoter region around exon a of the LDHA gene was completely methylated. Reverse transcription-PCR analysis and direct sequencing revealed that R51 cells expressed a RNA with the sequence of the human homolog of a murine testis-specific variant that has exon 0 as the 5′ noncoding sequence. LDHB was expressed normally in R51 cells.

Conclusions: The somatic LDHA in R51 cells is transcriptionally silenced by promoter hypermethylation around exon a, leaving only LDHB to be expressed normally and a testis-specific variant transcript of LDHA containing exon 0. LD2ex possibly results from tetramerization of three wild-type LDHB molecules and one variant LDHA product.

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.

Serum lactate dehydrogenase isoenzyme 1 and prediction of death in patients with metastatic testicular germ cell tumors

The International Germ Cell Cancer Collaborative Group study of patients with metastatic testicular germ cell tumors showed that catalytic concentration of serum lactate dehydrogenase (S-LD), serum alpha-fetoprotein concentration (S-AFP), and serum human chorionic gonadotropin concentration (S-hCG) predicted death from tumor. The recent international TNM classification (T primary tumor, N lymph node metastasis, M distant metastasis) is based on these results. The aim of our study was to evaluate whether catalytic concentration of S-LD isoenzyme 1 (S-LD-1) was a better predictor than the criteria used for the international classification. In an evaluation series of 44 patients from Odense University Hospital, Denmark, a raised S-LD-1 (>1.0 x upper limit of reference values) had a predictive value for death from tumor in 5-years observation of 46%. The predictive value was 46% for S-LD, 25% for S-AFP, and 40% for S-hCG. A normal SLD-1 had a predictive value for survival over 5-years observation of 100%. It was 81% for S-LD, 75% for SAFP, and 77% for S-hCG. The fraction of the patients who died of tumor and had a raised tumor marker value was 100% for S-LD-1, 46% for S-LD, 9% for S-AFP, and 18% for S-hCG. The fraction of patients with a normal serum tumor marker value among those who survived was 61% for S-LD-1, 81% for S-LD, 94% for SAFP, and 94% for S-hCG. A validation series of 37 patients treated at the University of Texas MD Anderson Cancer Center showed similar findings. Combining the patients in the two series, a raised value of SLD-1 classified more patients into a subgroup with an impaired survival (53%) than S-LD (35%), S-AFP (6%), or S-hCG (11%), and the high risk subgroups based on the international classification (40%). The findings have implications for the staging and treatment of patients with metastatic testicular 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.

Methods for the separation of lactate dehydrogenases and clinical significance of the enzyme

Lactate dehydrogenase (LDH), an ubiquitous enzyme among vertebrates, invertebrates, plants and microbes was discovered in the early period of enzymology. The enzyme has been dissolved in several distinguishable molecular forms. In mammals, three types of subunits encoded by the genes Ldh-A, Ldh-B and Ldh-C give rise to a selected number of tetrameric isoenzymes. LDH-A4, LDH-B4 and the mixed hybrid forms of the A- and B-subunits are present in many tissues but with certain distribution patterns. LDH-C4 is confined in mammals to testes and sperm. Numerous techniques have been employed to purify, characterize and separate the different forms of the enzyme. This report deals with the main protocols and procedures of purification of LDH and its isoenzymes including chromatographic and electrophoretic methods, partitioning in aqueous two-phase systems and precipitation approaches. In particular, affinity separation techniques based on natural and pseudo-biospecific ligands are described in detail. In addition, basic physico-chemical and kinetic properties of the enzyme from different sources are summarized in a second part, the clinical significance of the determination of LDH in diverse body fluids in respect to the total activity and the isoenzyme distribution in different organs is discussed.

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.

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

We investigated the impact of correction for contamination from hemolysis on serum lactate dehydrogenase isoenzyme 1 (S-LD-1) determinations. A study of hemolysates from 7 control patients showed a mean correction factor for the contamination of 0.1 U/L S-LD-1 for each 1 mg/L serum hemoglobin (S-Hb). S-LD-1 in a series of blood samples from 44 patients (EJC 1992;28:410-5) would decrease median 24 U/L (range 8-70 U/L) if the measurements were corrected with this factor. So we advice to correct S-LD-1 determinations for the contamination with a common correction based on the S-Hb concentrations in the samples.

Serum lactate dehydrogenase isoenzyme 1 and tumour volume are indicators of response to treatment and predictors of prognosis in metastatic testicular germ cell tumours

44 patients with metastatic testicular germ cell tumours treated with cisplatin-based chemotherapy were evaluated for prognostic implications of clinical characteristics. 22 obtained complete remission by the initial chemotherapy, and 30 are disease-free. S-LDH-1 had an overall predictive value regarding the response of 80%, S-LDH of 64%, S-AFP of 62%, and S-hCG of 62%. In multivariate analysis regarding response, only tumour volume classified according to the Royal Marsden system (P = 0.0036) and S-LDH-1 (P = 0.0069) yielded information. Regarding survival, S-LDH-1 (P = 0.0141) and an estimate of total tumour mass (P = 0.0171) had most impact with additional information from S-hCG only (P = 0.0536). We conclude that S-LDH-1 may be used as a tumour marker in addition to S-hCG and S-AFP in patients with metastatic testicular germ cell tumour.

An assessment of combined tumour markers in patients with seminoma: placental alkaline phosphatase (PLAP), lactate dehydrogenase (LD) and beta human chorionic gonadotrophin (beta HCG)

We have assessed the tumour markers placental alkaline phosphatase (PLAP), lactate dehydrogenase (LD), and human chorionic gonadotrophin (beta HCG) using 2,000 serum samples from 286 patients with seminoma. The ROC curves show that no one marker performs adequately for the detection of disease either at initial staging or during follow-up. We used a Markov model heuristically to devise strategies, in which marker results were assessed in combination, which might be useful in clinical practice. We found that the best strategy was to consider a test result abnormal only if either the beta HCG was greater than 6 Ul-1 or the LD was greater than 400 U l-1 and the PLAP level was greater than 60 U l-1. This will detect about 50% of patients with disease and the false-positive rate is 2%. In practical terms this means that PLAP need only be estimated in patients whose beta HCG is less than 6 IU l-1 and whose LD is greater than 400 U l-1.