Neuron-specific enolase--a serum tumour marker in seminoma?

Liquid Biopsies in the Clinical Management of Germ Cell Tumor Patients: State-of-the-Art and Future Directions

Liquid biopsies constitute a minimally invasive means of managing cancer patients, entailing early diagnosis, follow-up and prediction of response to therapy. Their use in the germ cell tumor field is invaluable since diagnostic tissue biopsies (which are invasive) are often not performed, and therefore only a presumptive diagnosis can be made, confirmed upon examination of the surgical specimen. Herein, we provide an overall review of the current liquid biopsy-based biomarkers of this disease, including the classical, routinely used serum tumor markers—the promising microRNAs rapidly approaching the introduction into clinical practice—but also cell-free DNA markers (including DNA methylation) and circulating tumor cells. Finally, and importantly, we also explore novel strategies and challenges for liquid biopsy markers and methodologies, providing a critical view of the future directions for liquid biopsy tests in this field, highlighting gaps and unanswered questions.

Identification and validation of a five apoptosis-related genes signature for prediction of disease-free survival for testicular germ cell tumors

Background

More and more studies have paid attention to the role of apoptosis in tumorigenesis. A variety of apoptosis-related genes (ARGs) are related to tumor progression and resistance to chemotherapy drugs. Therefore, this study aims to establish a prognostic marker for ARG-based testicular germ cell tumors (TCGT).

Methods

TCGT sequencing data and clinical information were downloaded from The Cancer Genome Atlas (TCGA) database and GEO database. The sequencing data of normal tissues came from the GTEx database. Through univariate COX, LASSO, and multiple COX regression analyses, we screened out key ARGs related to prognosis and constructed a risk signature and a prognostic nomogram. Finally, we performed internal and external verification to verify the signature we have established.

Results

Five ARGs, including CHGA, LPCAT1, PPP1CA, PSMB5, UBR2 were selected out and utilized to establish a novel signature. Based on this signature, TCGT patients were divided into high-risk groups and low-risk groups. The results showed that the disease-free survival (DFS) of patients in the high-risk group was lower than that in the low-risk group (P=0.02268). The subsequent univariate and multivariate Cox regression analysis further proved that the features we established are valuable independent prognostic factors (P<0.05). Also, a prognostic nomogram was created to visualize the relationship between various prognostic-related factors and the 1-, 3-, and 5-year DFS of TCGT in the TCGA cohort.

Conclusions

We constructed a new nomogram based on ARGs to predict the risk of testicular tumor recurrence. It can help clinicians better and more intuitively predict the survival of patients.

Glycan Analysis as Biomarkers for Testicular Cancer

The U.S. Preventive Services Task Force does not recommend routine screening for testicular cancer (TC) in asymptomatic men, essentially because serological testicular cancer (TC) biomarkers are not reliable. The main reason is that two of the most important TC biomarkers, α-fetoprotein (AFP) and human chorionic gonadotropin (hCG), are not produced solely due to TC. Moreover, up to 40% of patients with TC do not have elevated serological biomarkers, which is why serial imaging with CT is the chief means of monitoring progress. On the other hand, exposure to radiation can lead to an increased risk of secondary malignancies. This review provides the first comprehensive account of the applicability of protein glycoprofiling as a promising biomarker for TC with applications in disease diagnostics, monitoring and recurrence evaluation. The review first deals with the description and classification of TC. Secondly, the limitations of current TC biomarkers such as hCG, AFP and lactate dehydrogenase are provided together with an extensive overview of the glycosylation of hCG and AFP related to TC. The final part of the review summarises the potential of glycan changes on either hCG and AFP as TC biomarkers for diagnostics and prognostics purposes, and for disease recurrence evaluation. Finally, an analysis of glycans in serum and tissues as TC biomarkers is also provided.

Testicular Cancer Biomarkers: A Role for Precision Medicine in Testicular Cancer

Testicular germ cell tumors (TGCTs) represent the most common solid tumors among men aged 15 to 34 years. Fortunately, recent advances have made testicular cancer a highly curable disease. Despite the high cure rates, there are still several areas in testis cancer care where treatment decisions are controversial and guided only with clinical factors and historic serum tumor markers. Unfortunately, unlike other genitourinary malignancies, modern research techniques have not been widely tested or applied to germ cell tumors, perhaps as a result of excellent prognosis in this cohort of young men. Despite this, there remain numerous challenges and pitfalls in testis cancer care that need to be addressed. A reliable set of biomarkers could be extremely useful in helping risk-stratify patients, detect relapse early, guide surgical decision-making, and tailor follow-up. Current tumor markers (Alpha-fetoprotein, human chorionic gonadotrophin, and lactate dehydrogenase) have low accuracy and low sensitivity when used not only as diagnostic but also as prognostic and predictive markers. In twenty-first century medicine, there is a role for further prognostic stratification and the development of novel biomarkers that offer greater sensitivity and specificity for TGCTs. Despite the initial promising results, the majority of preclinical biomarkers do not, as yet have a proven validated role in clinical practice, and future prospective trials are needed to support and confirm the results of cohort studies. In this narrative review, we aimed to highlight the recent innovations in the development and implementation of novel testicular tumor markers and discuss their clinical applications and limitations in the management of this disease.

Neuron-Specific Enolase

The clinical value of neuron-specific enolase as a marker in small cell lung cancer, neuroblastoma, melanoma and seminoma has been reviewed The role of serum and cerebrospinal NSE in benign and malignant disease of the central nervous sytem is discussed.

Neuron-Specific Enolase as a Biomarker: Biochemical and Clinical Aspects

Neuron-specific enolase (NSE) is known to be a cell specific isoenzyme of the glycolytic enzyme enolase. In vertebrate organisms three isozymes of enolase, expressed by different genes, are present: enolase α is ubiquitous; enolase β is muscle-specific and enolase γ is neuron-specific. The expression of NSE, which occurs as γγ- and αγ-dimer, is a late event in neural differentiation, thus making it a useful index of neural maturation.NSE is a highly specific marker for neurons and peripheral neuroendocrine cells. As a result of the findings of NSE in specific tissues under normal conditions, increased body fluids levels of NSE may occur with malignant proliferation and thus can be of value in diagnosis, staging and treatment of related neuroendocrine tumours (NETs).NSE is currently the most reliable tumour marker in diagnosis, prognosis and follow-up of small cell lung cancer (SCLC), even though increased levels of NSE have been reported also in non-small cell lung cancer (NSCLC). The level of NSE correlates with tumour burden, number of metastatic sites and response to treatment.NSE can be also useful at diagnosis of NETs and gastroenteropancreatic (GEP)-NETs.Raised serum levels of NSE have been found in all stages of neuroblastoma, although the incidence of increased concentration is greater in widespread and metastatic disease. Moreover, NSE determination in cord blood offers an early postnatal possibility of confirming the diagnosis of neuroblastoma in newborns.NSE has been demonstrated to provide quantitative measures of brain damage and/or to improve the diagnosis and the outcome evaluation in ischaemic stroke, intracerebral hemorrhage, seizures, comatose patients after cardiopulmonary resuscitation for cardiac arrest and traumatic brain injury.Increased NSE serum levels have also been found associated with melanoma, seminoma, renal cell carcinoma, Merkel cell tumour, carcinoid tumours, dysgerminomas and immature teratomas, malignant phaechromocytoma, Guillain-Barré syndrome and Creutzfeldt-Jakob disease.

Role of biochemical markers in testicular cancer: diagnosis, staging, and surveillance

Testis cancer is one of the few solid organ malignancies for which reliable serum tumor markers are available to help guide disease management. Human chorionic gonadotropin, alpha fetoprotein, and lactate dehydrogenase play crucial roles in diagnosis, staging, prognosis, monitoring treatment response, and surveillance of seminomatous and nonseminomatous germ cell tumors. Herein we discuss the clinical applications of germ cell tumor markers, the limitations of these markers in the management of this disease, and additional serum molecules that have been identified with potential roles as novel germ cell tumor markers.

[The role of tumour markers in diagnosis and management of testicular germ cell tumours]

Alpha-fetoprotein (AFP), human choriogonadotropin (hCG) and lactate dehydrogenase (LDH) are established tumour markers of testicular germ cell tumours (TGCT) which are used according to the guidelines for primary diagnosis, staging, monitoring of therapeutic response and follow-up. Placental alkaline phosphatase and neurone-specific enolase play no role at all in the diagnosis and management of TGCT.Metastasized TGCT are classified according to the IGCCCG classification system into tumours with good, intermediate and poor prognosis depending on their serum concentration. The risk classification has a direct impact on therapy and determines the intensity of chemotherapy. In rare cases AFP and hCG might be elevated due to non-testicular reasons which have to be taken into consideration for the differential diagnosis especially if marker concentration and clinical presentation do not match. Response to chemotherapy is monitored with AFP and hCG which are determined the day before initiation of the next treatment cycle. Marker increases during or shortly after discontinuation of chemotherapy indicate a poor prognosis and make the immediate initiation of salvage treatment regimes necessary. Only 40-50% and 30% of relapses in patients under active surveillance for clinical stage I disease and after systemic chemotherapy are associated with marker increases. The remainder will be diagnosed by imaging studies or clinical symptoms. Marker increases have to be validated by imaging studies. However, about 10% of all relapsing patients have marker increases only without any imaging evidence of metastatic disease. Residual masses of any size and location have to be treated by postchemotherapy resection once the marker concentration is normalized or once it has reached a stable plateau. So-called desperation surgery in the presence of rising tumour markers is only indicated if no curative chemotherapy is available, all residual masses are completely resectable and no hCG elevation are observed. For follow-up, AFP, hCG and LDH should be evaluated for advanced TGCT and clinical stage I nonseminomas, whereas clinical stage I seminomas should be monitored without any markers.

National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for Use of Tumor Markers in Testicular, Prostate, Colorectal, Breast, and Ovarian Cancers

Background: Updated National Academy of Clinical Biochemistry (NACB) Laboratory Medicine Practice Guidelines for the use of tumor markers in the clinic have been developed.

Methods: Published reports relevant to use of tumor markers for 5 cancer sites—testicular, prostate, colorectal, breast, and ovarian—were critically reviewed.

Results: For testicular cancer, α-fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase are recommended for diagnosis/case finding, staging, prognosis determination, recurrence detection, and therapy monitoring. α-Fetoprotein is also recommended for differential diagnosis of nonseminomatous and seminomatous germ cell tumors. Prostate-specific antigen (PSA) is not recommended for prostate cancer screening, but may be used for detecting disease recurrence and monitoring therapy. Free PSA measurement data are useful for distinguishing malignant from benign prostatic disease when total PSA is &lt;10 μg/L. In colorectal cancer, carcinoembryonic antigen is recommended (with some caveats) for prognosis determination, postoperative surveillance, and therapy monitoring in advanced disease. Fecal occult blood testing may be used for screening asymptomatic adults 50 years or older. For breast cancer, estrogen and progesterone receptors are mandatory for predicting response to hormone therapy, human epidermal growth factor receptor-2 measurement is mandatory for predicting response to trastuzumab, and urokinase plasminogen activator/plasminogen activator inhibitor 1 may be used for determining prognosis in lymph node–negative patients. CA15-3/BR27–29 or carcinoembryonic antigen may be used for therapy monitoring in advanced disease. CA125 is recommended (with transvaginal ultrasound) for early detection of ovarian cancer in women at high risk for this disease. CA125 is also recommended for differential diagnosis of suspicious pelvic masses in postmenopausal women, as well as for detection of recurrence, monitoring of therapy, and determination of prognosis in women with ovarian cancer.

Conclusions: Implementation of these recommendations should encourage optimal use of tumor markers.

Neuron Specific Enolase (NSE): A Valuable Prognostic Factor of Central Nervous System Dysfunction Following Cardiac Surgery

Purpose

The aim of this study was to evaluate neuron specific enolase (NSE) as prognostic factor for CNS disorders developed in relation to cardiac surgery.

Patients and methods

A cohort of 92 patients were divided into two groups; the experimental group consisted of patients undergoing open-heart bypass surgery (50 patients) and the control group consisting of 42 patients undergoing general surgery procedures. The blood levels of NSE were measured in both groups before and 24 h after the operation and have been related to the incidence of the postoperative brain damage as well as to the duration of the extracorporeal circulation (ECC).

Results

The analysis of our results showed that the changes of blood NSE levels, before and immediately after ECC in open-heart surgery have been related to the incidence of postoperative brain dysfunction according to a specific mathematical equation. This incidence was raised also in relation to the age of the patient and the duration of ECC. On the contrary, NSE seems to have no prognostic value in general surgery.

Conclusion

NSE can be used in cardiac surgery as a simple and reliable prognostic factor to predict postoperative brain dysfunction.

A list of candidate cancer biomarkers for targeted proteomics

We have compiled from literature and other sources a list of 1261 proteins believed to be differentially expressed in human cancer. These proteins, only some of which have been detected in plasma to date, represent a population of candidate plasma biomarkers that could be useful in early cancer detection and monitoring given sufficiently sensitive specific assays. We have begun to prioritize these markers for future validation by frequency of literature citations, both total and as a function of time. The candidates include proteins involved in oncogenesis, angiogenesis, development, differentiation, proliferation, apoptosis, hematopoiesis, immune and hormonal responses, cell signaling, nucleotide function, hydrolysis, cellular homing, cell cycle and structure, the acute phase response and hormonal control. Many have been detected in studies of tissue or nuclear components; nevertheless we hypothesize that most if not all should be present in plasma at some level. Of the 1261 candidates only 9 have been approved as "tumor associated antigens" by the FDA. We propose that systematic collection and large-scale validation of candidate biomarkers would fill the gap currently existing between basic research and clinical use of advanced diagnostics.

A list of candidate cancer biomarkers for targeted proteomics

We have compiled from literature and other sources a list of 1261 proteins believed to be differentially expressed in human cancer. These proteins, only some of which have been detected in plasma to date, represent a population of candidate plasma biomarkers that could be useful in early cancer detection and monitoring given sufficiently sensitive specific assays. We have begun to prioritize these markers for future validation by frequency of literature citations, both total and as a function of time. The candidates include proteins involved in oncogenesis, angiogenesis, development, differentiation, proliferation, apoptosis, hematopoiesis, immune and hormonal responses, cell signaling, nucleotide function, hydrolysis, cellular homing, cell cycle and structure, the acute phase response and hormonal control. Many have been detected in studies of tissue or nuclear components; nevertheless we hypothesize that most if not all should be present in plasma at some level. Of the 1261 candidates only 9 have been approved as "tumor associated antigens" by the FDA. We propose that systematic collection and large-scale validation of candidate biomarkers would fill the gap currently existing between basic research and clinical use of advanced diagnostics.

Chromosomes, genes, and development of testicular germ cell tumors

A literature review found 265 articles on testicular germ cell tumors (TGCTs) detailing the copy number of chromosomal regions and expression of 245 genes. An initial precursor stage, intratubular germ cell neoplasia (IGCN), is characterized by triploidization and an upregulation of KIT, ALPP, CCDN2, and ZNF354A, and a downregulation of CDKN2D. TGCT regularly have a series of chromosomal aberrations: a decrease in copy number at 4q21 approximately qter and 5q14 approximately qter; an increase at 7p21 approximately pter, 7q21 approximately q33, and 8q12 approximately q23 (especially high increase in seminoma); a decrease at 11p11 approximately p15 and 11q14 approximately q24; an increase at 12p11 approximately pter; a decrease at 13q14 approximately q31; an increase of 17q11 approximately q21 (only for nonseminoma); a decrease of 18q12 approximately qter; and an increase at 21q21 approximately qter, 22q11 approximately qter (only for seminoma), and Xq. Macroscopically overt TGCT is associated with a characteristic series of abnormalities in the retinoblastoma pathway including upregulation of cyclin D2 and p27 and downregulation of RB1 and the cyclin-dependent kinase inhibitors p16, p18, p19, and p21. TGCT thus has a synergistic pattern in gene expressions of the retinoblastoma pathway that is rare in other malignancies.

Malignant fibrous histiocytoma masquerading as germ cell tumor by producing beta-human chorionic gonadotropin and neuron-specific enolase

Neuron-specific enolase and beta-human chorionic gonadotropin are serum markers frequently found associated with germ cell tumors. To our knowledge, we report the first case of a malignant fibrous histiocytoma producing both markers and discuss the significance of this unusual condition in the differential diagnosis of retroperitoneal tumors.

Technical performance and diagnostic utility of the new Elecsys neuron-specific enolase enzyme immunoassay

This international multicenter study was designed to evaluate the technical performance of the new double-monoclonal, single-step Elecsys neuron-specific enolase (NSE) enzyme immunoassay (EIA) and to assess its utility as a sensitive and specific test for the diagnosis of small-cell lung cancer (SCLC). Intra- and interassay coefficients of variation, determined in five control or serum specimens in six laboratories, ranged from 0.7 to 5.3 (inter-laboratory median: 1.3%) and from 1.3 to 8.5 (inter-laboratory median: 3.4%), respectively. Laboratory-to-laboratory comparability was excellent with respect to recovery and inter-assay coefficients of variation. The test was linear between 0.0 and 320 ng/ml (highest measured concentration). There was a significant correlation between NSE concentrations measured using the Elecsys NSE and the established Cobas Core NSE EIA II in all subjects (n = 723) and in patients with lung cancer (n = 333). However, NSE concentrations were systematically lower (approximately 9%) with the Elecsys NSE than with the comparison test. Based on a specificity of 95% in comparison with the group suffering from benign lung diseases (n = 183), the cut-off value for the discrimination between malignant and benign conditions was set at 21.6 ng/ml. NSE was raised in 73.4% of SCLC patients (n = 188) and was significantly higher (p < 0.01) in extensive (87.8%) as opposed to limited disease (56.7%). NSE was also elevated in 16.0% of the cases with non-small cell lung cancer (NSCLC, n = 374). It is concluded that the Elecsys NSE EIA is a reliable and accurate diagnostic procedure for the measurement of NSE in serum samples. The special merits of this new assay are the wide measuring range (according to manufacturer's declaration up to 370 ng/ml) and a short incubation time of 18 min.

New tumor markers of testis cancer

Potential tumor markers for testis cancer have become numerous with the new molecular techniques available. New protein markers have been evaluated, and histologic factors have shown correlations with stage of disease. Cytogenetic analysis studies have also shown associations with stage progression. Chromosomal markers, oncogenes, and tumor suppressor genes are possible candidates for tumor markers. These new potential tumor markers may become as commonplace as the established markers and may enhance diagnosis, staging, and treatment of testis cancer.

Tumor markers in hydrocele fluids of patients with benign and malignant scrotal diseases

PURPOSE

We evaluated the presence of human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP) and a panel of other tumor markers in the compartment next to the tumor (that is, the malignant hydrocele fluid).

MATERIALS AND METHODS

We measured hCG, AFP, neuron-specific enolase, carcinoembryonic antigen and cytokeratin-19 fragments in cubital vein sera and in hydrocele fluids of patients with testicular cancer. Results were compared with those obtained from hydrocele fluids of patients with benign disease.

RESULTS

All tumor markers remained under the respective cutoff values in benign hydroceles. In patients with pure seminomas, hCG levels were elevated in 66% of hydroceles but only once in peripheral sera, whereas AFP remained low in both compartments. Furthermore, of 11 cases of nonseminomatous germ cell tumor hydrocele fluids, 3 with negative peripheral tumor marker values had to be reclassified marker positive, of which 2 showed elevated hCG levels and 1 had increased levels of AFP. Significant changes of neuron-specific enolase and carcinoembryonic antigen concentrations could not be observed. However, a cytokeratin-19 fragment measured by Cyfra 21-1 assay was elevated in 2 of 3 seminomatous and in 4 of 8 nonseminomatous hydroceles.

CONCLUSIONS

These data give a new insight into the in vivo secretion pattern of testicular germ cell neoplasms, which demonstrates that the term "marker negative" should be restricted to selected cases of testicular cancer. Analysis of tumor markers in hydrocele fluids may be a helpful tool in patients with scrotal swelling if clinical and sonographic results remain uncertain.

Immunoreactive neuron-specific enolase (NSE) is expressed in testicular carcinoma-in-situ

Neuron-specific enolase (NSE) is a well-known marker of tumours that have neuroendocrine origin. High levels of NSE have also been described in various types of testicular germ cell neoplasms, particularly in seminomas. To evaluate the presence of NSE in testicular carcinoma-in situ (CIS), a preinvasive stage of testicular germ cell tumours, a panel of CIS tissue specimens was examined. Fifteen of 18 (83 per cent) CIS samples showed immunohistochemical staining with anti-NSE monoclonal antibody. Immunoreactivity has also been found in overt testicular germ cell tumours, including seminomas, non-seminomas, and a mixed germ cell tumour. As the co-existence of high NSE production and gene amplification of N-myc has been reported in some tumours, including germ cell tumours, the expression of the protein product of N-myc was also examined in this study, but only sporadic cases showed N-myc staining. These results are evidence against a relationship between NSE and N-myc in testicular germ cell tumours. The high expression of NSE in CIS and overt germ cell tumours may be due to the increased gene dosage effect associated with the overrepresentation of isochromosome 12p.

Testicular neoplasms and tumoral markers

The use of tumoral markers and especially of BHCG and AFP in the diagnosis, staging and follow-up of patients affected by testicle germinai neoplasms is now widespread. Nevertheless, controversies stili exist in each one of these fields. Especially for clinical staging, high percentages of understaging of stage I tumours are reported in literature with considerable effects on therapeutical indications and prognosis. The Authors attempt a criticai review on the use of markers for diagnosis and staging of testicular neoplasms based upon their own experience of 79 cases over a 14-year period.

Testicular seminoma stage I: treatment results and long-term follow-up (1968-1988)

Sixty-nine patients with stage I testicular seminoma were referred to the Northern Israel Oncology Center between 1968 and 1987. Sixty-four patients were irradiated postoperatively and five patients had surveillance alone. Complete follow-up was available for all patients, with a median follow-up of 86 months (range 9-239 months). The last follow-up was in December 1988. Actuarial survival was 94% to 5, 10, 15, and 20 years. Six patients relapsed following completion of irradiation. All the recurrences occurred outside the radiation field. Three of the relapsed patients could be salvaged with cisplatinum-based chemotherapy and are alive at 4, 7, and 10 years following second-line treatment. Acute or chronic side effects were mild and manageable. Seven patients developed second primary cancers, two within and six outside the radiation field. While surveillance policy alone in stage I testicular seminoma may be successful in terms of patient outcome, it requires prolonged observation, good compliance of patients, and intensive use of resources. Thus, until proved otherwise, infradiaphragmatic radiotherapy should further remain the optimal routine treatment in seminoma patients with stage I disease.