Chromosome abnormalities of eighty-one pediatric germ cell tumors: Sex-, age-, site-, and histopathology-related differences?a Children's Cancer Group study

Molecular genetic analysis of central nervous system germ cell tumors with comparative genomic hybridization

The limited information available to date regarding the genetic alterations in germ cell tumors of the central nervous system has raised concerns about their biologic relationship to other germ cell tumor entities. We investigated fresh-frozen or archival tumor samples from 19 patients with central nervous system germ cell tumors (CNS-GCTs), including seven germinomas, eight malignant nongerminomatous germ cell tumors and four teratomas, using chromosomal comparative genomic hybridization to determine recurrent chromosomal imbalances. All 15 malignant CNS-GCTs and two of four teratomas showed multiple chromosomal imbalances. Chromosomal gains (median: 4 gains/tumor, range: 0-9 gains/tumor) were observed more frequently than losses (median: 1.6 losses/tumor, range: 0-6 losses/tumor). Gain of 12p, which is considered characteristic for germ cell tumors of the adult testis, was detected in 11 of 19 tumors and 10 of 15 malignant CNS-GCTs. In one tumor, gain of 12p was confined to an amplicon at 12p12, corresponding to the commonly amplified region on 12p. Other common gains were found on chromosome arms 1q and 8q (n = 9, each). Among the chromosomal losses, parts of chromosome 11 (n = 5), 18 (n = 4), and 13 (n = 3) were deleted most frequently. Notably, we observed no difference in the genetic profiles of germinomatous and nongerminomatous CNS-GCTs; however, the average number of imbalances was higher in the latter group. A meta-analysis comparing 116 malignant gonadal and extragonadal germ cell tumors revealed that the genomic alterations in CNS-GCTs are virtually indistinguishable from those found in their gonadal or other extragonadal counterparts of the corresponding age group. These data strongly argue in favor of common pathogenetic mechanisms in gonadal and extragonadal germ cell tumors.

Imbalances of chromosome arm 1p in pediatric and adult germ cell tumors are caused by true allelic loss: A combined comparative genomic hybridization and microsatellite analysis

Previous studies on childhood germ cell tumors (GCTs) report highly variable frequencies of losses at chromosome arm 1p. Since deletions at 1p portend a poor prognosis in other embryonal tumors, this study aims to clarify the question of the frequency of true allelic loss at 1p and whether it constitutes a prognostic parameter. We analyzed 13 GCTs from different gonadal and extragonadal sites of children (4 teratomas, 9 malignant GCTs) and 18 GCTs of adolescents and adults (3 teratomas; 15 malignant GCTs) using automated microsatellite analysis with 23 polymorphic markers and chromosomal "high resolution" comparative genomic hybridization (HR-CGH). With this combined approach, we detected loss of heterozygosity (LOH) at 1p in 8/9 childhood malignant GCTs with concordant data from HR-CGH and microsatellite analyses. In contrast, LOH at 1p was not detected in childhood teratomas (0/4) and constituted a rare event in GCTs of adolescence and adulthood (3/18). The commonly deleted region was located at distal 1p36-pter, with a proximal boundary between the markers D1S450 and D1S2870. These data unequivocally demonstrate that deletion at 1p is common in childhood GCTs and results in allelic loss. This observation argues for the presence of a classical tumor suppressor at distal 1p. Considering the high frequency of LOH at 1p and the overall favorable prognosis of childhood GCTs, a prognostic impact of LOH at 1p in childhood GCTs appears unlikely. However, since two postpubertal tumors with LOH at 1p progressed, a prognostic relevance in this age group seems possible, warranting a prospective evaluation.

New evidence for the origin of intracranial germ cell tumours from primordial germ cells: expression of pluripotency and cell differentiation markers

Primary intracranial germ cell tumours are rare neoplasms that occur in children and adolescents. This study examined both the biology and the origin of these tumours, as it has been hypothesized that they originate from a totipotent primordial germ cell. We applied recent knowledge from gonadal germ cell tumours and analysed expression of a wide panel of stem cell-related proteins (C-KIT, OCT-3/4 (POU5F1), AP-2gamma (TFAP2C), and NANOG) and developmentally regulated germ cell-specific proteins (including MAGE-A4, NY-ESO-1, and TSPY). Expression at the protein level was analysed in 21 children and young adults with intracranial germinomas and non-germinomas, contributing to a careful description of these unusual tumours and adding to the understanding of pathogenesis. Stem cell related proteins were highly expressed in intracranial germ cell tumours, and many similarities were detected with their gonadal equivalents, including a close similarity with primordial germ cells. A notable difference was the sex-specific expression of TSPY, a gene previously implicated in the origin of gonadoblastoma. TSPY was only detected in germ cell tumours in the central nervous system (CNS) from males, suggesting that it is not required for the initiation of malignant germ cell transformation. The expression of genes associated with embryonic stem cell pluripotency in CNS germ cell tumours strongly suggests that these tumours are derived from cells that retain, at least partially, an embryonic stem cell-like phenotype, which is a hallmark of primordial germ cells.

Involvement of adenomatous polyposis coli (APC) gene in testicular yolk sac tumor of infants

The pathogenesis of testicular yolk sac tumor (YST) of infants is still unclear. Infantile YSTs rarely show isochromosome 12p or aneuploidy, which are common in adult germ cell tumors. On the other hand, recent epigenetic studies suggest the involvement of some tumor suppressor genes, including the adenomatous polyposis coli (APC) gene. In the present study, we examined 10 infantile pure YSTs for mutation, allelic loss, promoter methylation, and protein expression status of the APC gene to evaluate whether the APC gene plays a significant role in the pathogenesis of infantile YSTs. Loss of heterozygosity at 5q21, where the APC gene is localized, was detected in at least 3 (30%) of the 9 YSTs examined. None of the 10 YSTs showed mutations. Promoter methylation was detected in 7 (70%) of the 10 YSTs; among 7 YSTs showing methylation, 3 YSTs also harbored loss of heterozygosity at 5q21. Immunohistochemically, 8 infantile YSTs did not express the APC protein, whereas 2 YSTs without showing APC methylation, as well as germ cells of normal infantile testes, expressed this protein in the cytoplasm. These data indicate that inactivation of the APC gene, by allelic loss and/or promoter methylation, is related to the occurrence of infantile YSTs.

Dramatic response of malignant craniopharyngioma to cis-platin-based chemotherapy. Should craniopharyngioma be considered as a suprasellar 'germ cell' tumour?

The case is described of a 21-year-old woman, who developed a malignant tumour arising from a craniopharyngioma 14 years after the original diagnosis. The remarkable response of this malignant tumour ex-craniopharyngioma to cis-platin based chemotherapy, together with other midline tumour characteristics of craniopharyngioma, raise the question as to whether craniopharyngioma should any longer be separately considered from suprasellar germ cell tumour. This subject is discussed.

Fusion of the SUMO/Sentrin-specific protease 1 gene SENP1 and the embryonic polarity-related mesoderm development gene MESDC2 in a patient with an infantile teratoma and a constitutional t(12;15)(q13;q25)

Recently, we identified a patient with an infantile sacrococcygeal teratoma and a constitutional t(12;15)(q13;q25). Here, we show that, as a result of this chromosomal translocation, the SUMO/Sentrin-specific protease 1 gene (SENP1) on chromosome 12 and the embryonic polarity-related mesoderm development gene (MESDC2) on chromosome 15 are disrupted and fused. Both reciprocal SENP1-MESDC2 (SEME) and MESDC2-SENP1 (MESE) fusion genes are transcribed in tumor-derived cells and their open reading frames encode aberrant proteins. As a consequence of this, and in contrast to wild-type (WT) MESDC2, the translocation-associated SEME protein is no longer targeted to the endoplasmatic reticulum, leading to a presumed loss-of-function as a chaperone for the WNT co-receptors LRP5 and/or LRP6. Ultimately, this might lead to abnormal development and/or routing of germ cell tumor precursor cells. SUMO, a post-translational modifier, plays an important role in several cellular key processes and is cleaved from its substrates by WT SENP1. Using a PML desumoylation assay, we found that translocation-associated MESE proteins exhibit desumoylation capacities similar to those observed for WT SENP1. We speculate that spatio-temporal disturbances in desumoylating activities during critical stages of embryonic development might have predisposed the patient. Together, the constitutional t(12;15)(q13;q25) translocation revealed two novel candidate genes for neonatal/infantile GCT development: MESDC2 and SENP1.

Germ cell tumors of the gonads: a selective review emphasizing problems in differential diagnosis, newly appreciated, and controversial issues

Gonadal germ cell tumors continue to be the cause of diverse, diagnostically challenging issues for the pathologist, and their correct resolution often has major important therapeutic and prognostic implications. They are academically interesting because of the biological diversity exhibited in the two gonads and variation in frequency of certain neoplasms. The most dramatic examples of the latter are the frequency of dermoid cyst in the ovary compared to the testis and the reverse pertaining to embryonal carcinoma. Within the teratoma group, there is strong evidence that ovarian and prepubertal testicular teratomas are derived from benign germ cells, a pathogenesis that likely applies also to the rare dermoid cysts and uncommon epidermoid cysts of the testis. In contrast, postpubertal testicular teratomas derive from malignant germ cells, specifically representing differentiation within a preexistent nonteratomatous cancer. As expected, given the foregoing, teratomas in boys are clinically benign, whereas in postpubertal males they are malignant, independent of their degree of immaturity. On the other hand, immaturity is an important finding in ovarian teratomas, irrespective of age, although its significance in children has recently been challenged. It is usually recognized on the basis of embryonic-appearing neuroepithelium, which shows mitotic activity and apoptosis in contrast to differentiated neuroepithelial tissues, which may occur in mature ovarian teratomas. Rarely it is based on the presence of cellular, mitotically active glial tissue. Fetal-type tissues alone are not sufficient for a diagnosis of immature teratoma. Further differences between the teratomatous tumors in the two gonads are the relative frequency of monodermal teratomas in the ovary in contrast to the testis, where only one subset, carcinoids, is seen with any frequency. When uncommon somatic-type malignancies (usually squamous cell carcinoma) occur in mature cystic teratomas of the ovary, this is a de novo form of malignant transformation; similar tumors in the testis, a very rare event, represent overgrowth of teratomatous elements that originated from malignant, nonteratomatous germ cell tumors and, therefore, had previously undergone malignant transformation. Germinomas may have several unusual features in each gonad; these include microcystic arrangements that suggest yolk sac tumor, tubular patterns that mimic Sertoli cell tumor, apparent increased cytological atypia that causes concern for embryonal carcinoma, and prominent syncytiotrophoblast giant cells that suggest choriocarcinoma. Awareness of these variants, good technical preparations, the retained typical cytological features of germinoma cells, and the judicious use of tailored panels of immunohistochemical stains resolve these dilemmas in virtually all instances. Two aspects of germinomas are unique to the testis. Firstly, intertubular growth of small seminomas may cause them to be overlooked. Secondly, the distinctive spermatocytic seminoma occurs only in the testis. A newly recognized aspect of this tumor is the propensity for some to be relatively monomorphic, making them apt to be mistaken for usual seminoma or embryonal carcinoma, although the characteristic polymorphic appearance in some foci, absence of intratubular germ cell neoplasia, unclassified type, and immunohistochemical stains should prevent this error. Cytoplasmic membrane immunoreactivity for placental alkaline phosphatase and CD117, with usual negativity for AE1/AE3 cytokeratins, is helpful in the diagnosis of germinoma. The recently described marker, OCT3/4, a nuclear transcription factor, is especially helpful in the differential of germinoma and embryonal carcinoma with other neoplasms. Yolk sac tumor continues to be confused occasionally with clear cell carcinoma of the ovary. Glandular ('endometrioid-like') yolk sac tumors mimic endometrioid carcinomas; predominant or pure hepatoid yolk sac tumors cause concern for metastatic hepatocellular carcinoma or, in the ovary, primary hepatoid carcinoma, and solid patterns, especially in limited samplings, may be misinterpreted as germinoma. The usually younger age of patients with yolk sac tumors helps with the differential considerations with the nongerm cell tumors, as do other clinical and microscopic features and selected immunohistochemical stains. Choriocarcinoma is rare in both gonads, and those in the ovary must be distinguished from metastatic tumors of placental origin. Syncytiotrophoblast cells alone, admixed with other forms of germ cell tumor, still are confused with choriocarcinoma, but this phenomenon, which is much more frequent than choriocarcinoma, lacks the plexiform arrangement of different trophoblast cell types that typifies the latter. Mixed germ cell tumors (which may show almost any combination of components) are common in the testis but rare in the ovary. A separately categorized, rare form of mixed germ cell tumor seen in both gonads is the polyembryoma. It is perhaps the most photogenic of all gonadal germ cell tumors and is also intriguing because of its distinctive, organized arrangement of yolk sac tumor and embryonal carcinoma elements and recapitulation of very early embryonic development, even to the extent of having in its fundamental unit, the embryoid body, a miniature yolk sac, and amniotic cavity. These tumors, which are constituted by innumerable embryoid bodies, almost always contain teratomatous glands in minor amounts, and one way of viewing the polyembryoma is to consider it the most immature form of teratoma. Embryoid bodies are also common as a minor component of many mixed germ cell tumors, particularly in the testis, and the diffuse embryoma is another variant that has a particular arrangement of yolk sac tumor and embryonal carcinoma elements. Regression of gonadal germ cell tumors is a phenomenon restricted to the testis, for unknown reasons. These so-called 'burnt-out' germ cell tumors can be recognized by a distinctive constellation of findings, including sometimes minor foci of residual recognizable germ cell neoplasia, a well-defined zone of scarring (often having residual ghost tubules), associated lymphoplasmacytic infiltrate, intratubular calcification and, in about 50%, of in situ germ cell neoplasia.

Identification of recurrent chromosomal aberrations in germ cell tumors of neonates and infants using genomewide array-based comparative genomic hybridization

Human germ cell tumors (GCTs) of neonates and infants comprise a heterogeneous group of neoplasms, including teratomas and yolk sac tumors with distinct clinical and epidemiologic features. As yet, little is known about the cytogenetic constitution of these tumors. We applied the recently developed genomewide array-based comparative genomic hybridization (array CGH) technology to 24 GCTs derived from patients under the age of 5 years. In addition, we included seven tumors derived from children and adolescents older than 5 years. In the series from those under the age of 5 years, most teratomas displayed normal profiles, except for some minor recurrent aberrations. In contrast, the yolk sac tumors displayed recurrent losses of 1p35-pter and gains of 3p21-pter and of 20q13. In the GCTs of patients older than 5 years, the main recurrent anomalies included gains of 12p and of whole chromosomes 7 and 8. In addition, gains of the 1q32-qter region and losses of the 6q24-qter and 18q21-qter regions were frequent in GCTs of varied histology, independent of age. We concluded that array CGH is a highly suitable method for identifying recurrent chromosomal anomalies in GCTs of neonates and infants. The recurrent anomalies observed point to chromosomal regions that may harbor novel diagnostic/prognostic identifiers and genes relevant to the development of these neoplasms.

IGF2/H19 imprinting analysis of human germ cell tumors (GCTs) using the methylation-sensitive single-nucleotide primer extension method reflects the origin of GCTs in different stages of primordial germ cell development

Previous studies have demonstrated biallelic expression of the imprinted genes H19 and IGF2 and loss of DNA methylation of the SNRPN gene, indicating a common precursor cell of human germ cell tumors (GCTs), namely, the primordial germ cell (PGC). In this study, we applied the methylation-sensitive single-nucleotide primer extension (MS-SNuPE) technique to the analysis of the IGF2/H19 imprinting control region (ICR) in 55 GCTs from representative clinical and histologic subgroups. Most GCTs showed low methylation at the IGF2/H19 ICR. All 8 ovarian GCTs, 9 of 10 testicular seminomas, 7 of 10 testicular nonseminomas (all in adolescents/adults), 6 of 9 testicular yolk sac tumors (YSTs), and 12 of 14 nongonadal GCTs (all in infants/children) were hypomethylated. The highest methylation was observed in three childhood YSTs (boys) and 2 of 4 spermatocytic seminomas. The latter are derived from more advanced stages of germ-cell development. The predominantly low methylation of most of the other GCTs correlates with studies that demonstrated erasure of the methylation imprint of the IGF2/H19 ICR during embryonal PGC migration and development. These findings suggest that the IGF2/H19 methylation status in GCTs might reflect preservation of the physiologic imprinting erasure in PGCs rather than a loss of imprinting in a sense that is accepted for somatic tumors. Furthermore, this study indicates that imprinting control mechanisms other than the proposed CTCF (CCCTC binding factor) boundary model regulate IGF2 expression during this stage of PGC development as well as in GCTs derived from PGC. (c) 2005 Wiley-Liss, Inc.

Trisomy 14pter --> q21: a case with associated ovarian germ cell tumor and review of the literature

We report a patient with trisomy X and a supernumerary marker chromosome. The marker chromosome was characterized by comparative genomic hybridization and shown to be derived from chromosome 14, resulting in trisomy for 14pter --> q21. The karyotype was thus redefined as 48,XXX,+mar.rev ish enh(14pterq21). The patient presented with facial dysmorphism and a high-pitched cry, exhibited severe developmental delay, and developed an aggressive ovarian immature teratoma. In this paper, we also review reports of 11 other patients with constitutional trisomy of the same chromosomal region. Previous studies have identified somatic gains of chromosome 14 in ovarian germ cell tumors. We propose that the constitutional gain of chromosomal 14 material may have predisposed to the development of this tumor.

A novel 1p36.2 located gene, APITD1, with tumour-suppressive properties and a putative p53-binding domain, shows low expression in neuroblastoma tumours

Neuroblastoma is characterised by a lack of TP53 mutations and no other tumour suppressor gene consistently inactivated has yet been identified in this childhood cancer form. Characterisation of a new gene, denoted APITD1, in the neuroblastoma tumour suppressor candidate region in chromosome 1p36.22 reveals that APITD1 contains a predicted TFIID-31 domain, representing the TATA box-binding protein-associated factor, TAF_II31, which is required for p53-mediated transcription activation. Two different transcripts of this gene were shown to be ubiquitously expressed, one of them with an elevated expression in foetal tissues. Primary neuroblastoma tumours of all different stages showed either very weak or no measurable APITD1 expression, contrary to the level of expression observed in neuroblastoma cell lines. A reduced pattern of expression was also observed in a set of various tumour types. APITD1 was functionally tested by adding APITD1 mRNA to neuroblastoma cells, leading to the cell growth to be reduced up to 90% compared to control cells, suggesting APITD1 to have a role in a cell death pathway. Furthermore, we determined the genomic organisation of APITD1. Automated genomic DNA sequencing of the coding region of the gene as well as the promoter sequence in 44 neuroblastoma tumours did not reveal any loss-of-function mutations, indicating that mutations in APITD1 is not a common abnormality of neuroblastoma tumours. We suggest that low expression of this gene might interfere with the ability for apoptosis through the p53 pathway.

Thiotepa-Based High-Dose Chemotherapy With Autologous Stem-Cell Rescue in Patients With Recurrent or Progressive CNS Germ Cell Tumors

Purpose

To evaluate the efficacy and toxicity of high-dose chemotherapy (HDC) followed by autologous stem-cell rescue (ASCR) in patients with relapsed or progressive CNS germ cell tumors (GCTs).

Patients and Methods

Twenty-one patients with CNS GCTs who experienced relapse or progression despite having received initial chemotherapy and/or radiotherapy were treated with thiotepa-based HDC regimens followed by ASCR.

Results

Estimated overall survival (OS) and event-free survival (EFS) rates for the entire group 4 years after HDC were 57% ± 12% and 52% ± 14%, respectively. Seven of nine (78%) patients with germinoma survived disease-free after HDC with a median survival of 48 months. One patient died as a result of progressive disease (PD) 39 months after HDC, and another died as a result of pulmonary fibrosis unrelated to HDC 78 months after ASCR without assessable disease. However, only four of 12 patients (33%) with nongerminomatous germ cell tumors (NGGCTs) survived without evidence of disease, with a median survival of 35 months. Eight patients with NGGCTs died as a result of PD, with a median survival of 4 months after HDC (range, 2 to 17 months). Patients with germinoma fared better than those with NGGCTs (P = .016 and .014 for OS and EFS, respectively). Patients with complete response to HDC also had significantly better outcome (P < .001 for OS and EFS) compared with patients with only a partial response or stable disease. There were no toxic deaths because of HDC.

Conclusion

Dose escalation of chemotherapy followed by ASCR is effective therapy for patients with recurrent CNS germinomas and might be effective in patients with recurrent NGGCTs with a low tumor burden.

Epidemiologic analysis of 1,442 children and adolescents registered in the German germ cell tumor protocols

BACKGROUND

Germ cell tumors (GCTs) constitute a heterogeneous group of tumors that significantly vary with respect to their clinical presentation and biology. The objective of this analysis was to analyze a large population-based pediatric cohort of GCTs and to evaluate the parameters age, sex, site of the tumor, histology, and potential correlations between these parameters.

PROCEDURE

Between 1981 and 2000, 1,442 patients were prospectively enrolled onto the German protocols for testicular and non-testicular GCTs. Tumors were histologically classified according to the WHO.

RESULTS

We observed a bimodal age distribution with a first peak during infancy and a second after the onset of puberty. At birth, almost all tumors were teratomas, sometimes with microfoci of yolk sac tumor, which on the other hand, was the predominant histology during childhood. After the onset of puberty, germinomatous GCTs represented the most frequent histological subtype, and malignant non-germinomatous GCTs often presented as mixed tumors with choriocarcinoma and embryonal carcinoma components. During infancy, non-gonadal GCTs accounted for the majority of GCTs, while after the onset of puberty, gonadal GCTs predominated. Notably, among non-gonadal GCTs, there was a female predominance during childhood and a strong male predominance during adolescence.

CONCLUSIONS

Two separate groups of GCTs with distinct clinical features relevant for differential diagnosis and the diagnostic assessment can be distinguished. This observation correlates with genetic studies that reveal different genetic changes in childhood and adolescence GCTs. Further studies are needed to elucidate the molecular mechanisms of germ cell and GCT development that account for the age- and sex-dependent clinical manifestation.

Gonadal teratomas: a review and speculation

Teratomas of the ovary and testis are confusing because, despite histologic similarities, they exhibit different biologic behaviors, depending mostly on the site of occurrence and the age of the patient. Thus, most ovarian teratomas are benign, and most testicular teratomas are malignant, with the exception of those occurring in children. These general statements, however, do not hold true for ovarian teratomas that are "immature" or exhibit "malignant transformation" and for dermoid and epidermoid cysts of the testis, categories of ovarian and testicular teratomas that are malignant and benign, respectively. This review concentrates on some of the "newer" observations concerning these interesting and confusing neoplasms, including diagnostically deceptive patterns. It is the author's opinion that much of the confusion regarding gonadal teratomas can be clarified by the concept that the usual ovarian teratoma derives from a benign germ cell in a parthenogenetic-like fashion, whereas the typical postpubertal testicular example derives from a malignant germ cell, mostly after evolution of that originally malignant cell to an invasive germ cell tumor (ie, embryonal carcinoma, yolk sac tumor, etc). The postpubertal testicular teratomas can therefore be thought of as an end-stage pattern of differentiation of a malignant germ cell tumor. The pediatric testicular teratomas, as well as dermoid and epidermoid cysts of the testis, however, must derive from benign germ cells, in a fashion similar to most ovarian teratomas. The teratomatous components of mixed germ cell tumors of the ovary, on the other hand, likely have a pathogenesis similar to that of postpubertal testicular teratomas.

Hypermethylation of the RUNX3 gene promoter in testicular yolk sac tumor of infants

Testicular yolk sac tumor (YST) of infants is biologically distinct from its adult counterpart. Cytogenetically, YSTs in infants generally lack i(12p), which is highly characteristic of adult germ cell tumors (GCTs), whereas they frequently show a deletion of 1p36, indicating that the loss of a certain gene(s) in this region is an important event in the pathogenesis of infantile YSTs. In the present study, we examined 10 testicular YSTs from infants for promoter methylation status of the RUNX3 gene, localizing in 1p36.1, and loss of heterozygosity (LOH) in this region, on the presumption that RUNX3 acts as a tumor suppressor. Methylation of RUNX3 and LOH at 1p36.1 were detected in 8 of 10 (80%) and 6 of 8 (75%) infantile YSTs examined, respectively. All six cases harboring LOH showed RUNX3 methylation. In contrast, 0 of 12 adult GCTs showed RUNX3 methylation, and LOH at 1p36.1 was less frequent (1 of 6 cases: 16%) in adult GCTs. There is a significant difference in RUNX3 methylation between these 2 groups (P < 0.001). In normal testes of the young group, RUNX3 methylation was not detected. These results strongly suggest that RUNX3 is one of the tumor suppressors involved in the pathogenesis of testicular YSTs in infants.

Prognostic value of tumor size, metastases, extension into bone, and increased tumor marker in children with malignant sacrococcygeal germ cell tumors: a prospective evaluation of 71 patients treated in the German cooperative protocols Maligne Keimzelltumoren (MAKEI) 83/86 and MAKEI 89

PURPOSE

To evaluate the prognostic value of metastases, extension into bone, and alpha-fetoprotein (AFP) elevation in children with malignant sacrococcygeal germ cell tumors (GCTs) prospectively collected in two cooperative Maligne Keimzelltumoren (MAKEI) protocols (83/86 and 89).

PATIENTS AND METHODS

Between October 1983 and October 1995, 76 of 210 registered patients with sacrococcygeal primaries presented either with pure yolk sac tumor, embryonal carcinoma (EC), or yolk sac tumor and EC mixed with immature and mature teratoma elements. Stages T1 and T2 disease were diagnosed in 15 and 61 children, respectively, 41 patients had metastases, and 35 children presented with extension into bone. At diagnosis, 22 children had an AFP elevation of less than 10,000 ng/mL. Thirty-six children showed an AFP level between 10,000 and 100,000 ng/mL, and 12 patients had values of greater than 100,000 ng/mL. Five patients died of complication during treatment and were excluded from further evaluation. Seventy-one patients could be analyzed.

RESULTS

The 5-year relapse-free survival rate (RFS, Kaplan-Meier) was 0.76 +/- 0.03 (54 of 71 patients; median observation time, 54 months after diagnosis). The RFS of patients with and without metastases was different, but not significantly so (0.71 v 0.82). The outcome of patients with extension into bone (n = 31) and without this extension (n = 40) was 0.71 versus 0.80 (RFS, 5 years). Above-normal AFP level had no prognostic significance (P =.52).

CONCLUSION

In children with malignant sacrococcygeal GCTs treated with an intensive, short-interval, platinum-based regimen, the stage, extent of metastases, extension into bone, and AFP level had no prognostic significance.

Genetics and biology of male germ cell tumors

The application of cytogenetic and molecular genetic techniques to the study of germ cell tumors has yielded many clues to the etiology and chemosensitivity of these tumors. With the advent of expression profiling and genome-scanning technologies, it may be possible to identify molecular markers of germ cell tumor outcome and molecular networks important in human development and chemotherapeutic response.

Hypomethylated X chromosome gain and rare isochromosome 12p in diverse intracranial germ cell tumors

Twenty-five primary intracranial germ cell tumors (11 germinomas, 5 teratomas, 5 mixed teratomas-germinomas. 1 mixed choriocarcinoma-teratoma, 1 yolk sac tumor, 1 mixed yolk sac tumor-teratoma, and 1embryonal carcinoma; from 24 males and 1 female) were studied by fluorescence in situ hybridization with probes to the X and Y chromosomes, chromosome 12p, the CDKN2A/p16 gene, and chromosome 13q-loci previously noted to be altered in either intracranial or systemic germ cell tumors. An increased number of X chromosomes, typically 1 extra copy, was observed in 23 of 25 cases (92%), with methylation-sensitive PCR demonstrating that the additional X chromosomes were hypomethylated in 13 of 16 (81%) studied tumors. Five cases (20%) had increased copy numbers of 12p (including tumors with isochromosome 12p), and 3 (12%) had 13q loss. No tumors had CDKN2A/p16 deletion or mutation, and 16 of 25 (64%) were positive for p16 expression by immunohistochemistry. Genetic alterations such as isochromosome 12p, 13q loss and CDKN2A/p16 are therefore not common in intracranial germ cell tumors. However, gains of hypomethylated, active X chromosomes occur in nearly all intracranial germ cell tumors, regardless of histological subtype. Along with the observed male predominance of intracranial germ cell tumors and the predisposition in Klinefelter syndrome patients for these lesions, the data argue strongly that sex chromosome aberrations, rather than isochromosome 12p, are integral to intracranial germ cell tumorigenesis

Infantile and adult testicular germ cell tumors. a different pathogenesis?

Most adult testicular germ cell tumors have a characteristic chromosomal abnormality that is an isochromosome 12p [i(12p)]. Furthermore, these tumors are characterized by a chromosome number in the triploid range and gains and losses of (parts of) specific chromosomes. Cytogenetic investigation of three cases of infantile testicular germ cell tumors, all diagnosed as yolk sac tumors, revealed highly abnormal karyotypes. We found one case to be diploid; the other two cases were in the hypertriploid/hypotetraploid range. Structural abnormalities of chromosomes 1, 3, and 6 were recurrent and no i(12p) was found. Our results, together with data from the literature, suggest that infantile and adult testicular germ cell tumors have a different origin and pathogenetic pathway. Aberrations of chromosomes 1, 3, and 6 may play an important role in the pathogenesis of infantile testicular yolk sac tumors.

Genetic analysis of mediastinal nonseminomatous germ cell tumors in children and adolescents

Primary mediastinal germ cell tumors (M-GCTs) represent a heterogeneous group of tumors that varies with regard to age at presentation, histologic differentiation, and outcome. We retrospectively analyzed archival tissue samples of mediastinal mature and immature teratomas (n = 15) and malignant nonseminomatous M-GCTs (n = 20) with comparative genomic hybridization (CGH). The aim of this study was to define distinct genetic subgroups of M-GCT among the pediatric cohort that may differ in their clinical behavior and prognosis. All pure teratomas showed normal CGH profiles. Malignant M-GCTs in infants and children < 8 years old most frequently showed a gain of 1q, 3, and 20q and a loss of 1p, 4q, and 6q. Gain of 12p and sex chromosomal abnormalities were not observed in this age group. In contrast, the gain of 12p was the most common aberration in M-GCTs that arose in children > or = 8 years old. Additional recurrent changes included the loss of chromosome 13 and the gain of chromosome 21. All ten adolescents with malignant M-GCT were male, and five showed a gain of the X chromosome. In two of these five patients, Klinefelter syndrome was confirmed by cytogenetic analysis or by fluorescence in situ hybridization (FISH). In conclusion, CGH analysis of M-GCTs defines distinct genetic subgroups. Mediastinal teratomas show no genetic gains or losses. Malignant M-GCTs in children < 8 years old show the same pattern of gains and losses identified in sacrococcygeal and testicular GCTs at this age, and they lack sex-chromosomal abnormalities. Malignant M-GCTs in children > or = 8 years old show the same genetic profile previously reported in gonadal GCTs at this age. In addition, approximately 50% demonstrate a gain of the X chromosome, consistent with Klinefelter syndrome. Cooperative group studies reveal a significantly better prognosis of malignant M-GCT arising in infants compared to that in adolescents, suggesting that these genetic differences are associated with differences in clinical behavior.

SNRPN methylation patterns in germ cell tumors as a reflection of primordial germ cell development

Studies examining altered imprinted gene expression in cancer compare the observed expression pattern to the normal expression pattern for a given tissue of origin, usually the somatic expression pattern for the imprinted gene. Germ cell tumors (GCTs), however, require a developmental stage-dependent comparison. To explore using methylation as an indicator of germ cell development, we determined the pattern of methylation at the 5' untranslated region of SNRPN in 89 GCTs from both children and adults. Fifty-one of 84 tumors (60.7%) (12/30 (40%) of cultured pediatric GCTs, 23/36 (63.9%) of frozen adult GCTs, and 16/23 (69.5%) of frozen pediatric GCTs, with five samples having results from both cultured and uncultured material) demonstrated a nonsomatic methylation pattern after dual digestion with XbaI, NotI, and Southern blot analysis. In contrast, only 2 of 18 (11%) control samples (16 non-GCTs and 2 normal ovaries) exhibited a nonsomatic pattern. In both cases, the result was shown to be due to copy number differences between maternal and paternal homologs, unlike the GCTs in which there was no evidence of an uneven homolog number. A comparison of the data for only the gonadal GCTs and the control data showed a highly significant difference in the proportion of tumors with methylation alterations at this locus (P = 0.0000539). Since there is no published evidence of the involvement of SNRPN methylation changes in the development of malignancy, the data suggest that the methylation pattern of SNRPN in GCTs reflects that of the primordial germ cell giving rise to the tumor.

Chromosomes 1 and 12 abnormalities in pediatric germ cell tumors by interphase fluorescence in situ hybridization

Chromosome studies of pediatric germ cell tumors (GCTs) show differences in abnormalities dependent on age, sex, tumor location, and histology. Previous studies suggest that loss of 1p is associated with a malignant phenotype, while amplification of 12p, a common finding in adult testicular GCTs, is uncommon in pediatric GCTs. Fifty-three pediatric GCTs were analyzed for 1p36 loss and 12p amplification by G-banding and dual-color interphase FISH with probes for the centromere and short arm of chromosomes 1 or 12. Twelve tumors with loss of 1p36 were identified. No deletion was detected in tumors with nonmalignant histology, such that there was a significant association of 1p loss with malignancy in these tumors (P = 0.00115). Five of 18 tumors from male patients had amplification of 12p, consistent with G-band results. Combined analysis of our data with those in the literature revealed a significant correlation of 12p amplification with patient age (P = 0.000196). Amplification of 12p was only seen in one of 35 tumors from female patients. Five female GCTs had numerical abnormalities of chromosome 12, and two tumors showed complete lack of 12p. This spectrum of abnormalities differs from what is seen in the male tumors, providing further evidence for different etiologies of GCTs between the sexes.

Comparative genomic and in situ hybridization of germ cell tumors of the infantile testis

Chromosomal information on germ cell tumors of the infantile testis, ie, teratomas and yolk sac tumors, is limited and controversial. We studied two teratomas and four yolk sac tumors using comparative genomic hybridization (CGH) and in situ hybridization. No chromosomal anomalies were found in the teratomas by any of the methods, not even after CGH on microdissected tumor cells. All yolk sac tumors showed aneuploidy, loss of parts of 4q and 6q, and gain of parts of 20q. Underrepresentation of parts of 8q and overrepresentation of parts of 3p, 9q, 12p, 17, 19q, and 22 were detected in most cases. In addition, one recurrent yolk sac tumor after a sacral teratoma was studied, showing a highly similar pattern of imbalances. While CGH demonstrated loss of 1p36 in one testicular yolk sac tumor, in situ hybridization revealed loss of this region in all yolk sac tumors. High-level amplification of the 12q13-q14 region was found in one yolk sac tumor. MDM2, of which the encoding gene maps to this chromosomal region, was found in all cases using immunohistochemistry, whereas no p53 could be detected. Accordingly, no mutations within exons 5 to 8 of the p53 gene were observed. These data prove the absence of gross chromosomal aberrations in teratomas of the infantile testis and show a characteristic pattern of gains and losses in the yolk sac tumors. Besides confirmation of previously found anomalies, recurrent losses of 1p21-31 and 4q23-33 and gains of 9q34 and 12p12-13 have not been reported before. While genetic inactivation of p53 seems unimportant in the pathogenesis of these tumors, biochemical inactivation by MDM2 might be involved. These data support the existence of three entities of germ cell tumors of the human testis: teratomas and yolk sac tumors of infants, seminomas and nonseminomas of adolescents and young adults, and spermatocytic seminomas of the elderly, each with its own specific pathogenesis.

Pediatric genitourinary tumors

Advances in our knowledge of pediatric genitourinary tumors are being made at both the basic science and clinical levels. The molecular mechanisms underlying these pediatric malignancies are being uncovered and will aid in uncovering novel treatments. Because of the high success rate in treating these tumors, treatment options are being modified to decrease both short- and long-term morbidity, while maintaining the improved survival.

Germ-cell tumors in childhood and adolescence. GPOH MAKEI and the MAHO study groups

In mature and immature teratoma the treatment is surgical. The risk of recurrence can be estimated from the parameters primary site (with the coccygeal tumors being most at risk), histological grade of immaturity and completeness of the primary resection including the adjacent organ of origin (coccyx, ovary, testis etc.). In case of a microscopically complete tumor resection there is no role for adjuvant chemo- or radiotherapy irrespective of the histological grade of immaturity. Malignant germ-cell tumors (GCT) account for 2.9% of all malignant tumors of children younger than 15 years of age. More than half of the tumors occur at extragonadal sites such as the ovaries (26%), the coccygeal region (24%), the testes (18%) and the brain (18%) represent then primary sites. In patients with extensive tumor growth, metastatic disease or secreting intracranial tumors a delayed tumor resection after preoperative chemotherapy is preferable. In these patients malignant non-seminomatous GCT may be diagnosed clinically due to the increased serum or cerebrospinal fluid levels of the tumor markers AFP and/or beta-HCG. Current risk adapted treatment protocols containing cisplatinum allow long-term remissions in about 80% including patients with bulky or metastatic tumors. In the cisplatinum era the prognostic factors like histology, primary site of the tumor and initial tumor stage have partly lost their former impressive significance in infants and children. On the other hand the completeness of the primary tumor resection according to oncological standards has been established as the most powerful prognostic parameter superior to tumor marker levels or primary site of the tumor.

Genetic analysis of childhood endodermal sinus tumors by comparative genomic hybridization

Childhood endodermal sinus tumors (CEST) are a distinct category of germ cell tumors that involve the testis and extragonadal sites of young children. Recurrent deletions of 1p and 6q have been reported by classic cytogenetic analysis of a small number of cases. Comparative genomic hybridization, a technique that screens the entire genome for genetic abnormalities, is applied to additionally define the genetic changes present in CESTs. Sixteen frozen CESTs (10 testicular, 6 extragonadal) obtained from Pediatric Oncology Group-affiliated institutions or from the Cooperative Human Tissue Network were analyzed. The most common changes were gain of 20q (10 tumors), 1q (6 tumors), 11q and 22 (4 tumors each), and loss of 6q (8 tumors with common deleted region of 6q24-qter), 16q (4 tumors), and 1p (4 tumors). Localized regions of gain were identified at 8q24 (2 tumors both showing c-myc amplification by fluorescence in situ hybridization). Gain of 12p, characteristic of adolescent germ cell tumor, was present in one testicular tumor. Comparative genomic hybridization was useful in defining genetic differences between adult and childhood tumors, in determining the common regions deleted on chromosome 6, and in identifying other involved loci to be correlated with clinical parameters in future studies.

Pediatric germ cell tumors

Malignant germ cell tumors are relatively uncommon, accounting for approximately 3% of all childhood malignancies. Occurring with an incidence of approximately 4 per million among children less than 15 years of age, they account for approximately 225 new cases per year in the United States. Germ cell tumors occur in both gonadal and extragonadal sites, with extragonadal and testicular tumors predominating in children less than 3 years of age and with the gonads being the main location of tumors during and after puberty. They occur more frequently in girls than boys. Germ cell tumors are interesting for several reasons: (1) abnormal migration of primordial germ cells account for many of the childhood germ cell tumors; (2) markers exist to allow evaluation of the extent of resection and the development of recurrence for many of the tumors; and (3) the introduction of platinum-based chemotherapy has markedly improved the survival rate for germ cell tumors, as well as the salvage rate for recurrent or metastatic disease.