Germ cell tumors of the brain in children: a review of current literature and new advances in therapy

Molecular Pathology and Targeted Therapies for Personalized Management of Central Nervous System Germinoma

Intracranial germinomas are rare tumours, usually affecting male paediatric patients. They frequently develop in the pineal and suprasellar regions, causing endocrinological disturbances, visual deficits, and increased intracranial pressure. The diagnosis is established on magnetic resonance imaging (MRI), serum and cerebrospinal fluid (CSF) markers, and tumour stereotactic biopsy. Imaging techniques, such as susceptibility-weighted imaging (SWI), T2* (T2-star) gradient echo (GRE) or arterial spin labelling based perfusion-weighted MRI (ASL-PWI) facilitate the diagnosis. Germinomas are highly radiosensitive tumours, with survival rates >90% in the context of chemoradiotherapy. However, patients with resistant disease have limited therapeutic options and poor survival. The aim of this review is to highlight the genetic, epigenetic, and immunologic features, which could provide the basis for targeted therapy. Intracranial germinomas present genetic and epigenetic alterations (chromosomal aberrations, KIT, MAPK and PI3K pathways mutations, DNA hypomethylation, miRNA dysregulation) that may represent targets for therapy. Tyrosine kinase and mTOR inhibitors warrant further investigation in these cases. Immune markers, PD-1 (programmed cell death protein 1) and PD-L1 (programmed death-ligand 1), are expressed in germinomas, representing potential targets for immune checkpoint inhibitors. Resistant cases should benefit from a personalized management: genetic and immunological testing and enrolment in trials evaluating targeted therapies in intracranial germinomas.

Precocious puberty due to human chorionic gonadotropin secreting germinoma

This study aims to report a rare case of precocious puberty (PP) due to a human chorionic gonadotropin (hCG)-producing germinoma located in the suprasellar region. A 10-year-old male patient presented with sexual precocity, headache, drowsiness, loss of appetite, and papilledema. Significant acceleration of bone age in relation to chronological age, high serum total testosterone levels, and hypopituitarism (unresponsiveness to stimulation test) were observed. Magnetic resonance imaging (MRI) of the brain showed a large suprasellar tumor and triventricular dilatation. High hCG levels were found in both blood and cerebrospinal fluid. Hormone replacement therapy and transcranial surgery associated with radiotherapy were performed, with complete regression of sexual characteristics and normal laboratory tests post-operatively. Clinical and laboratory findings, in addition to MRI scans, led to the diagnosis of an hCG-producing tumor and PP, which represents a rare report in the literature.

CNS germinomas: what is the best treatment strategy?

CNS germ cell tumors are rare primary brain malignancies. Germinomas comprise approximately two-thirds of CNS germ cell tumors. Owing to their radiosensitivity, radiotherapy has been used to treat patients with CNS germinomas, with favorable treatment outcomes. Historically, craniospinal irradiation has been used. Given the concerns over long-term toxicities associated with craniospinal irradiation, reduced volume radiotherapy with or without chemotherapy has been employed. Data on the use of different strategies in the treatment of CNS germinomas are emerging but a standard strategy has not been established. This article reviews the different strategies used in the management of CNS germinomas.

[Hypogonadism despite of normal testosterone levels]

We report on a 19 year old patient with clinical signs of hypogonadism (small testicles, missing pollutions and diminished beard growth) despite of normal testosterone levels. Further diagnostic procedures revealed panhypopituitarism with insufficiency of the gonadotrope, somatotrope and corticotrope axis due to a beta-HCG-producing suprasellar germinoma with intracerebral metastases. Paraneoplastic production of beta-HCG resulted in sufficient stimulation of Leydig cells with normal production of testosterone, which had partly masked clinical symptoms of gonatrope insufficiency. The patient was treated by combined radiochemotherapy and is in remission since 7 years.

Refining the staging evaluation of pineal region germinoma using neuroendoscopy and the presence of preoperative diabetes insipidus

Treatment strategies for CNS germinoma are currently evolving. Current approaches include reducing the volume and dose of radiation by adding pre-irradiation chemotherapy. Very accurate staging is necessary with such an approach to prevent failures. Eight consecutive patients with pineal germinoma at one institution underwent endoscopic surgery for tumor biopsy, direct visualization of the third ventricular region, and third ventriculostomy for those with hydrocephalus. All patients were treated with 4 cycles of chemotherapy. Conformal field radiation therapy followed, with the dose to the tumor bed dependent on the response to chemotherapy. Patients who had MRI, endoscopic, or cerebrospinal fluid evidence of multicentric or disseminated disease also received craniospinal radiation. Six patients had diabetes insipidus (DI) at presentation. All 6 had tumor studding the floor of the third ventricle on endoscopic visualization, while only 4 of those patients had MRI evidence of disease in that region. All patients have completed therapy and are alive, with no evidence of disease at median follow-up of 31.5 months from diagnosis. Direct endoscopic visualization of the third ventricular region may be more sensitive than MRI for evaluating the presence of suprasellar disease and appears to add important information. This parameter should be added to the staging evaluation when feasible. In this series, the presence of DI was 100% predictive of suprasellar disease, even when the MRI was negative for involvement of that region. Patients should be evaluated for DI as part of the initial staging, and if it is present, the patients should be treated for suprasellar disease regardless of MRI findings.

Radiation therapy for intracranial germ cell tumors

PURPOSE

To review the combined experiences of University of California, San Francisco, and Stanford University Medical Center in the treatment of intracranial germ cell tumors (GCT) and to assess the impact of craniospinal radiation (CSI) on patterns of relapse, progression-free survival (PFS), and overall survival (OS).

PATIENTS AND METHODS

Ninety-three patients received radiation for newly diagnosed intracranial GCTs, including 49 germinomas, 16 nongerminomatous GCTs (NGGCT), and 28 with no biopsy. Median follow-up for surviving patients was 4.5 years (range 0.25-34). Tests for variables correlating with OS and PFS were conducted using Cox proportional hazards model.

RESULTS

Five-year PFS and OS rates were 60% +/- 15% and 68% +/- 14% for patients with NGGCT and 88% +/- 5% and 93% +/- 4% for those with germinoma. Of 6 patients with localized NGGCT who did not receive CSI, 1 experienced an isolated spinal recurrence but was salvaged. Of 41 patients with localized germinoma, 6 who received CSI and 35 who did not, no isolated spinal cord relapses occurred. Twenty-one patients with localized germinoma received neither CSI nor whole brain radiation. Of these, none of 18 with ventricular radiation relapsed. One of 3 patients with primary tumor radiation relapsed intracranially but had only received 11 Gy at initial treatment. On multivariate analysis, germinoma histology but not CSI correlated with improved PFS and OS.

CONCLUSION

CSI is not indicated in the treatment of localized germinomas. For patients with localized germinomas treated with radiation alone, we recommend ventricular irradiation followed by primary tumor boost to a total of 45-50 Gy.

Emerging paradigms in mind-body medicine

The emerging paradigms in medicine can be seen through mind-body interactions. Observations in many meditative traditions suggest a series of objective indicators of health beyond absence of disease. Several of the physical signs have been confirmed by research or are consistent with modern science. Further correlation with long term health outcome is needed. Integration of meditation with conventional therapy has enriched psychotherapy with parallels drawn between the Nine Step Qigong and Freudian developmental psychology. A unified theory of the chakra system and the meridian system widely used in traditional mind-body interventions and acupuncture is presented in terms of modern science based on the morphogenetic singularity theory. Acupuncture points originate from the organizing centers in morphogenesis. Meridians and chakras are related to the underdifferentiated, interconnected cellular network that regulates growth and physiology. This theory explains the distribution and nonspecific activation of organizing centers and acupuncture points; the high electric conductance of the meridian system; the polarity effect of electroacupuncture; the side-effect profile of acupuncture; and the ontogeny, phylogeny, and physiologic function of the meridian system and chakra system. It also successfully predicted several findings in conventional biomedical science. These advances have implications in many disciplines of medicine.