Radiation-induced brain tumours after central nervous system irradiation in childhood: a review

Epithelioid glioblastoma diagnosed 70 years after craniofacial radiotherapy

The authors report a rare case of most likely radiation-induced glioma (RIG) with epithelioid features and the presence of molecular features consistent with RIG. This occurred 70 years after craniofacial brachytherapy. Such a late development of radiation-induced glioblastoma (RIGBM) and the advanced age of presentation for an epithelioid glioblastoma are both unique in the literature. Despite not receiving the full course of adjuvant chemotherapy after surgery and radiotherapy, the patient displayed no signs of recurrence during a 5-year follow-up. RIGBM should be further studied to reveal potential unique clinical and molecular characteristics, as well as to better predict survival and treatment response.

Distinct patterns of copy number alterations may predict poor outcome in central nervous system germ cell tumors

We have previously reported that 12p gain may predict the presence of malignant components and poor prognosis for CNS germ cell tumor (GCT). Recently, 3p25.3 gain was identified as an independent predictor of poor prognosis for testicular GCT. Eighty-one CNS GCTs were analyzed. Copy number was calculated using methylation arrays. Five cases (6.2%) showed 3p25.3 gain, but only among the 40 non-germinomatous GCTs (NGGCTs) (5/40, 12.5%; p = 0.03). Among NGGCTs, those with a yolk sac tumor component showed a significantly higher frequency of 3p25.3 gain (18.2%) than those without (1.5%; p = 0.048). NGGCTs with gain showed significantly shorter progression-free survival (PFS) than those without (p = 0.047). The 3p25.3 gain and 12p gain were independent from each other. The combination of 3p25.3 gain and/or 12p gain was more frequent among NGGCTs with malignant components (69%) than among those without (29%; p = 0.02). Germinomas containing a higher number of copy number alterations showed shorter PFS than those with fewer (p = 0.03). Taken together, a finding of 3p25.3 gain may be a copy number alteration specific to NGGCTs and in combination with 12p gain could serve as a marker of negative prognosis or treatment resistance. Germinoma with frequent chromosomal instability may constitute an unfavorable subgroup.

A Longitudinal Study of Individual Radiation Responses in Pediatric Patients Treated with Proton and Photon Radiotherapy, and Interventional Cardiology: Rationale and Research Protocol of the HARMONIC Project

The Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy (photon and proton) in Pediatrics (HARMONIC) is a five-year project funded by the European Commission that aimed to improve the understanding of the long-term ionizing radiation (IR) risks for pediatric patients. In this paper, we provide a detailed overview of the rationale, design, and methods for the biological aspect of the project with objectives to provide a mechanistic understanding of the molecular pathways involved in the IR response and to identify potential predictive biomarkers of individual response involved in long-term health risks. Biological samples will be collected at three time points: before the first exposure, at the end of the exposure, and one year after the exposure. The average whole-body dose, the dose to the target organ, and the dose to some important out-of-field organs will be estimated. State-of-the-art analytical methods will be used to assess the levels of a set of known biomarkers and also explore high-resolution approaches of proteomics and miRNA transcriptomes to provide an integrated assessment. By using bioinformatics and systems biology, biological pathways and novel pathways involved in the response to IR exposure will be deciphered.

Incidence of second primary cancers among survivors of childhood cancer: A population-based study, Osaka, Japan, 1975-2015

Second primary cancer (SPC) is one of the most life-threatening late effects of childhood cancers. We investigated the incidence and survival outcomes of SPC in childhood cancer patients in Japan. Data were obtained from the population-based Osaka Cancer Registry. Individuals diagnosed with cancer at age 0-14 years during 1975-2014 and survived 2 months or longer were followed through December 2015. The risk of developing SPC was assessed with standardized incidence ratio (SIR), excess absolute risk (EAR, per 100,000 person-years), and cumulative incidence. Multivariable Poisson regression analysis was carried out to assess relative risks of SPC by treatment method. Survival analysis was undertaken using the Kaplan-Meier method. Of 7229 childhood cancer survivors, 101 (1.4%) developed SPC after a median of 11.6 years. Overall SIR was 5.0, which corresponded with 84.3 EAR. The cumulative incidence was 0.9%, 2.1%, and 3.4% at 10, 20, and 30 years, respectively. Among all SPCs, the type that contributed most to the overall burden was cancers in the central nervous system (EAR = 28.0) followed by digestive system (EAR = 15.1), thyroid (EAR = 8.3), and bones and joints (EAR = 7.8); median latency ranged from 2.0 years (lymphomas) to 26.6 years (skin cancers). Patients treated with radiotherapy alone were at a 2.58-fold increased risk of developing SPC compared to those who received neither chemotherapy nor radiotherapy. Among patients who developed SPCs, 5-year and 10-year survival probabilities after SPC diagnosis were 61.7% and 52.0%, respectively. Risk-based long-term follow-up planning is essential to inform survivorship care and help reduce the burden of SPCs in childhood cancer survivors.

Nutrition and Diet: A Double-Edged Sword in Development and Treatment of Brain Tumors

Brain tumor (BT) is the second most common pediatric cancer, one of the most common cancers among adults, and the major cause of cancer-related morbidity and mortality worldwide. Both genetics and environment can contribute to BT induction. One of the environmental risks is diet which has not been proven as a certain hazard yet. The objective of the current chapter was to review the literature concerning both positive and negative effects of nutrition on BT risk.

Biomarkers for risk-based treatment modifications for CNS germ cell tumors: Updates on biological underpinnings, clinical trials, and future directions

CNS germ cell tumors (GCTs) preferentially occur in pediatric and adolescent patients. GCTs are located predominantly in the neurohypophysis and the pineal gland. Histopathologically, GCTs are broadly classified into germinomas and non-germinomatous GCTs (NGGCTs). In general, germinoma responds well to chemotherapy and radiation therapy, with a 10-year overall survival (OS) rate of approximately 90%. In contrast, NGGCTs have a less favorable prognosis, with a five-year OS of approximately 70%. Germinomas are typically treated with platinum-based chemotherapy and whole-ventricular radiation therapy, while mature teratomas can be surgically cured. Other NGGCTs require intensive chemotherapy with radiation therapy, including whole brain or craniospinal irradiation, depending on the dissemination status and protocols. Long-term treatment-related sequelae, including secondary neoplasms and cerebrovascular events, have been well recognized. These late effects have a tremendous impact in later life, especially since patients are mostly affected in childhood or young adults. Intending to minimize the treatment burden on patients, the identification of biomarkers for treatment stratification and evaluation of treatment response is of critical importance. Recently, tumor cell content in germinomas has been shown to be closely related to prognosis, suggesting that cases with low tumor cell content may be safely treated with a less intensive regimen. Among the copy number alterations, the 12p gain is the most prominent and has been shown to be a negative prognostic factor in NGGCTs. MicroRNA clusters (mir-371-373) were also revealed to be a hallmark of GCTs, demonstrating the potential for the application of liquid biopsy in the diagnosis and detection of recurrence. Recurrent mutations have been detected in the MAPK or PI3K pathways, most typically in KIT and MTOR and low genome-wide methylation has been demonstrated in germinoma; this most likely reflects the cell-of-origin primordial germ cells for this tumor type. These alterations can also be leveraged for liquid biopsies of cell-free DNA and may potentially be targeted for treatment in the future. Advancements in basic research will be translated into clinical practice and can directly impact patient management. Additional understanding of the biology and pathogenesis of GCTs will lead to the development of better-stratified clinical trials, ultimately resulting in improved treatment outcomes and a reduction in long-term treatment-related adverse effects.

Risk of secondary malignant neoplasms in children following proton therapy vs. photon therapy for primary CNS tumors: A systematic review and meta-analysis

Background

Central nervous system tumors are now the most common primary neoplasms seen in children, and radiation therapy is a key component in management. Secondary malignant neoplasms (SMNs) are rare, but dreaded complications. Proton beam therapy (PBT) can potentially minimize the risk of SMNs compared to conventional photon radiation therapy (RT), and multiple recent studies with mature data have reported the risk of SMNs after PBT. We performed this systematic review and meta-analysis to characterize and compare the incidence of SMNs after proton and photon-based radiation for pediatric CNS tumors.

Methods

A systematic search of literature on electronic (PubMed, Cochrane Central, and Embase) databases was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. We included studies reporting the incidence and nature of SMNs in pediatric patients with primary CNS tumors. The crude incidence of SMNs and all secondary neoplasms were separately extracted, and the random-effects model was used for pooled analysis and subgroup comparison was performed between studies using photons vs. protons.

Results

Twenty-four studies were included for analysis. A total of 418 SMNs were seen in 38,163 patients. The most common SMN were gliomas (40.6%) followed by meningiomas (38.7%), sarcomas (4.8%), and thyroid cancers (4.2%). The median follow-up was 8.8 years [3.3–23.2].The median latency to SMN for photons and protons were 11.9 years [5-23] and 5.9 years [5-6.7], respectively. The pooled incidence of SMNs was 1.8% (95% CI: 1.1%–2.6%, I² = 94%) with photons and 1.5% (95% CI: 0%–4.5%, I² = 81%) with protons. The pooled incidence of all SNs was not different [photons: 3.6% (95% CI: 2.5%–4.8%, I² = 96%) vs. protons: 1.5% (95% CI: 0–4.5%, I² = 80%); p = 0.21].

Conclusion

We observed similar rates of SMN with PBT at 1.5% compared to 1.8% with photon-based RT for pediatric CNS tumors. We observed a shorter latency to SMN with PBT compared to RT. With increasing use of pencil beam scanning PBT and VMAT, further studies are warranted to evaluate the risk of secondary cancers in patients treated with these newer modalities.

Assessment of therapeutic outcome and role of reirradiation in patients with radiation-induced glioma

Background

We sought to clarify the optimal follow-up, therapeutic strategy, especially the role of reirradiation, and the diagnostic impact of isocitrate dehydrogenase (IDH) 1 and 2 mutation status in patients with radiation-induced glioma (RIG).

Methods

We retrospectively reviewed the clinical characteristics and treatment outcomes of 11 patients with high-grade glioma who satisfied Cahan’s criteria for RIG in our database during 2001–2021. IDH 1/2 mutations were analyzed by Sanger sequencing and/or pyrosequencing.

Results

The RIGs included glioblastoma with IDH 1/2 wild-type (n = 7), glioblastoma not otherwise specified (n = 2), anaplastic astrocytoma with IDH1/2 wild-type (n = 1), and anaplastic astrocytoma not otherwise specified (n = 1). The median period from primary disease and RIG diagnosis was 17 years (range: 9–30 years). All patients underwent tumor removal or biopsy, 5 patients postoperatively received reirradiation combined with chemotherapy, and 6 patients were treated with chemotherapy alone. The median progression-free and survival times were 11.3 and 28.3 months. The median progression-free survival time of patients treated with reirradiation and chemotherapy (n = 5) tended to be longer than that of patients that received chemotherapy alone (n = 6) (17.0 vs 8.1 months). However, the median survival time was similar (29.6 vs 27.4 months). Local recurrence was observed in 5 patients treated with chemotherapy alone, whereas in 2 patients among 4 patients treated with reirradiation and chemotherapy. None of the patients developed radiation necrosis. In one case, the primary tumor was diffuse astrocytoma with IDH2 mutant, and the secondary tumor was glioblastoma with IDH 1/2 wild-type. Based on the difference of IDH2 mutation status, the secondary tumor with IDH 1/2 wild-type was diagnosed as a de novo tumor that was related to the previous radiation therapy.

Conclusions

RIG can occur beyond 20 years after successfully treating the primary disease using radiotherapy; thus, cancer survivors should be informed of the long-term risk of developing RIG and the need for timely neuroimaging evaluation. Reirradiation combined with chemotherapy appears to be feasible and has favorable outcomes. Determining the IDH1/2 mutational status is useful to establish RIG diagnosis when the primary tumor is glioma.

Defining the molecular features of radiation-induced glioma: A systematic review and meta-analysis

Background

Cranial radiation therapy is essential in treating many pediatric cancers, especially brain tumors; however, its use comes with the risk of developing second malignancies. Cranial radiation-induced gliomas (RIGs) are aggressive high-grade tumors with a dismal prognosis, for which no standard therapy exists. A definitive molecular signature for RIGs has not yet been established. We sought to address this gap by performing a systematic review and meta-analysis of the molecular features of cranial RIGs.

Methods

A systematic review of the literature was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles and case reports that described molecular analyses of cranial radiation-induced high-grade gliomas were identified and evaluated, and data extracted for collation.

Results

Of 1727 records identified, 31 were eligible, containing 102 unique RIGs with molecular data. The most frequent genetic alterations in RIGs included PDGFRA or TP53 mutations, PDGFRA or CDK4 amplifications, and CDKN2A deletion, along with 1q gain, 1p loss and 13q loss. Of note, mutations in ACVR1, EGFR, H3F3A, HIST1H3B, HIST1H3C, IDH2, SMARCB1 or the TERT promoter were not observed. A comparative analysis revealed that RIGs are molecularly distinct from most other astrocytomas and gliomas and instead align most closely with the pedGBM_RTK1 subgroup of pediatric glioblastoma.

Conclusions

This comprehensive analysis highlights the major molecular features of RIGs, demonstrates their molecular distinction from many other astrocytomas and gliomas, and reveals potential genetic drivers and therapeutic targets for this currently fatal disease.

The Japan Society for Neuro-Oncology Guideline on the Diagnosis and Treatment of Central Nervous System Germ Cell Tumors

Primary CNS germ cell tumors (GCTs) are rare neoplasms predominantly observed in the pediatric and young adult populations. In line with the hypothesis that the primordial germ cell is the cell-of-origin, histopathological examinations for this pathology involve a diverse range of components mirroring the embryogenic developmental dimensions. Chemotherapy and radiotherapy are the mainstays of treatment, with surgery having a limited role for diagnosis and debulking of residual tissue after treatment. While better management has been achieved over recent decades by modifying radiation coverage and selecting appropriate chemotherapy, standardization of treatment remains challenging, partly due to the low volume of cases encountered in each institution. As the incidence is higher in East Asia, including Japan, the Japan Society for Neuro-Oncology established a multidisciplinary task force to create an evidence-based guideline for CNS GCTs. This guideline provides recommendations for multiple dimensions of clinical management for CNS GCTs, with particular focus on diagnostic measures including serum markers, treatment algorithms including surgery, radiotherapy and chemotherapy, and under-investigated but important areas such as treatment for recurrent cases, long-term follow-up protocols and long-term sequelae. This guideline serves the purpose of helping healthcare professionals keep up to date with current knowledge and standards of management for patients with this rare disease in daily clinical practice, as well as driving future translational and clinical research by recognizing unmet needs concerning this tumor.

Low tumor cell content predicts favorable prognosis in germinoma patients

Background

Germinoma preferentially occurs in pediatric and young adult age groups. Although they are responsive to treatment with chemotherapy and radiation, the treatment may cause long-term sequelae in their later lives. Here, we searched for clinical and histopathological features to predict the prognosis of germinoma and affect treatment response.

Methods

A total of 114 germinoma cases were included in the analysis. We investigated the association between clinical factors, tumor cell content, and progression-free survival (PFS).

Results

The tumor cell content was widely distributed from <5% to 90% in the specimens, with a median value of 50%. Female patients showed higher tumor cell content in the specimens (P = .002). Cases with lesions at atypical sites showed shorter PFS than those with lesions at other sites (P = .03). Patients with a higher tumor cell content (≥50%) showed shorter PFS than those with a lower tumor cell content (<50%) (P = .03). In multivariate analysis, tumor cell content was the only statistically significant prognostic factor (P = .04). Among the 7 cases treated with local radiation and chemotherapy, all 3 cases that recurred (2 outside of the radiation field, 1 unknown) had tumor cell content of ≥50% in the original specimen, whereas all 4 cases without recurrence had tumor cell contents of <50%.

Conclusions

We found that tumor cell content significantly affected the prognosis of germinomas. Although validation of these results using an independent and larger cohort is necessary, this potentially opens the possibility of leveraging this pathological factor in future clinical trials when stratifying the treatment intensity.

High-Grade Gliomas in Children-A Multi-Institutional Polish Study

Simple Summary

High-grade gliomas constitute less than 5% of pediatric brain tumors. Due to the rarity of such a diagnosis, the lack of consensus about the best therapeutic approach, and the difficulty in conducting prospective trials; a retrospective multi-institutional analysis, such as the one presented in this article, is needed. We carried out the survival analysis of children diagnosed and treated with high-grade gliomas in seven major polish institutions. The assessment of the outcome of 82 consecutive patients with grade III and grade IV tumors was performed and showed a 5-year overall survival of only 30%. The extent of resection, immediate temozolomide-based chemotherapy, and radical radiotherapy were found as factors positively influencing survival.

Abstract

Due to the rarity of high-grade gliomas (HGG) in children, data on this topic are scarce. The study aimed to investigate the long-term results of treatment of children with HGG and to identify factors related to better survival. We performed a retrospective analysis of patients treated for HGG who had the main tumor located outside the brainstem. The evaluation of factors that correlated with better survival was performed with the Cox proportional-hazard model. Survival was estimated with the Kaplan–Meier method. The study group consisted of 82 consecutive patients. All of them underwent surgery as primary treatment. Chemotherapy was applied in 93% of children with one third treated with temozolomide. After or during the systemic treatment, 79% of them received radiotherapy with a median dose of 54 Gy. Median follow-up was 122 months, and during that time, 59 patients died. One-, 2-, 5-, and 10-year overall survival was 78%, 48%, 30% and 17%, respectively. Patients with radical (R0) resection and temozolomide-based chemotherapy had better overall survival. Progression-free survival was better in patients after R0 resection and radical radiotherapy. The best outcome in HGG patients was observed in patients after R0 resection with immediate postoperative temozolomide-based chemotherapy and radical radiotherapy.

Reduction of pTau and APP levels in mammalian brain after low-dose radiation

Brain radiation can occur from treatment of brain tumors or accidental exposures. Brain radiation has been rarely considered, though, as a possible tool to alter protein levels involved in neurodegenerative disorders. We analyzed possible molecular and neuropathology changes of phosphorylated-Tau (pTau), all-Tau forms, β-tubulin, amyloid precursor protein (APP), glial fibrillary acidic protein (GFAP), ionized calcium binding adaptor molecule 1 (IBA-1), myelin basic protein (MBP), and GAP43 in Frontal Cortex (FC), Hippocampus (H) and Cerebellum (CRB) of swine brains following total-body low-dose radiation (1.79 Gy). Our data show that radiated-animals had lower levels of pTau in FC and H, APP in H and CRB, GAP43 in CRB, and higher level of GFAP in H versus sham-animals. These molecular changes were not accompanied by obvious neurohistological changes, except for astrogliosis in the H. These findings are novel, and might open new perspectives on brain radiation as a potential tool to interfere with the accumulation of specific proteins linked to the pathogenesis of various neurodegenerative disorders.

Novel Diagnostic Methods and Posttreatment Clinical Phenotypes Among Intracranial Germ Cell Tumors

BACKGROUND

Central nervous system (CNS) germ cell tumors (GCT) are rare and complex pediatric neoplasms, the optimal management of which remains an area of active investigation.

OBJECTIVE

To present an updated cohort study, with particular attention to novel diagnostic methods and posttreatment clinical phenotypes.

METHODS

A single-institution cohort study of 80 primary, neurosurgically managed, CNS GCTs was conducted at Mayo Clinic, 1988-2017.

RESULTS

Postchemotherapy resection (eg, second-look surgery) was frequently required (27.0%), especially after adjuvant therapies for nongerminomatous GCTs (NGGCTs; 14 of 28 cases, excluding mature teratoma) and significantly associated with pineal lesions, as compared to neurohypophyseal or bifocal lesions (43.6% vs 5.9% vs 6.7%, P = .004), a finding that retained statistical significance after adjusting for index extent of resection and histology (P = .04). Essentially every NGGCT case underwent at least 1 craniotomy, either on presentation, as second-look surgery, or following local recurrence. Mature teratomatous tissue was highly incident in second-look specimens (84.2%), even among lesions initially diagnosed as germinomas. Pretreatment cerebrospinal fluid (CSF) cell fraction analysis demonstrated an association between single lesions and neutrophil predominance, whereas nongerminomatous GCTs were associated with increased monocyte fractions.

CONCLUSION

CNS GCTs are clinically heterogeneous lesions, resulting in numerous opportunities for improved understanding and clinical management via novel diagnostic and therapeutic protocols. Samples from second-look surgeries for recurrent germinomas frequently demonstrate teratomatous tissue, suggesting possible underdiagnosis of mixed GCTs-particularly among pineal lesions. GCT subtypes demonstrate differential cell fraction distributions on CSF analysis, a novel and perhaps diagnostically helpful finding that requires validation in external cohorts.

Cancer Predisposition Syndromes Associated With Pediatric High-Grade Gliomas

Pediatric High-Grade Gliomas (pHGG) are among the deadliest childhood brain tumors and can be associated with an underlying cancer predisposing syndrome. The thorough understanding of these syndromes can aid the clinician in their prompt recognition, leading to an informed genetic counseling for families and to a wider understanding of a specific genetic landscape of the tumor for target therapies. In this review, we summarize the main pHGG-associated cancer predisposing conditions, providing a guide for suspecting these syndromes and referring for genetic counseling.

[Intracranial meningiomas in children]

Meningiomas are rare in children and distinguished from the tumors in adults by clinical and biological aspects. Moreover, some histological forms and localizations are even casuistic in adults. There were 178 patients younger 18 years old with brain tumors. All patients underwent surgery at the pediatric department for 5-year period. Meningiomas were diagnosed in 5 cases that accounted for 2.8% of the total number of brain tumors in children. The authors reported children with intracranial meningiomas and discussed certain features of the course of disease in these patients.

Meningiomas in children

Meningiomas in children are poorly understood because they are rare. Recent reports have provided a more complete description of their incidence, genetics, imaging features, and outcome. In general, meningiomas in children are more likely to be higher grade, present in atypical locations, and have a higher risk of recurrence. The challenges encountered in children with respect to surgical and postoperative management are unique. Improved understanding of pediatric meningiomas, as well as the availability of new surgical, medical, and radiation therapies, creates opportunities to improve outcomes in this unique population.

Comprehensive analysis of meningioma in the first two decades of life: A systematic review

PURPOSE

To evaluate the relationship between meningioma histological subtype and tumor site in under-20 year-olds.

METHODS

A review of the literature on meningioma during the first 2 decades of life was carried out through a Medline search up to February 2019. To evaluate the adult population, a cross-sectional study was conducted on patients operated on between 2000 and 2014 in a single institution. Exclusion criteria comprised: series reports and papers that lacked detailed description of clinical findings, neuroimaging confirmation of tumor location, and/or at least 5 years' follow-up.

RESULTS

One hundred and seven manuscripts were included, for 365 under-20 year-old patients: 200 male, and 164 female. Histopathology found 197 cases (53.9%) of WHO grade I meningioma, with predominance of meningothelial (41.1%) and transitional (30.9%) subtypes; 123 (33.7%) grade II, and 45 (12.3%) grade III. For 65 (18.25%) of the 356 cases, recurrence was documented, with only 24 deaths (6.7%).

CONCLUSION

Meningioma in this population presented 2 differences compared to the adult population: male predominance, and high incidence of atypical meningioma. Surgery was the primary treatment. Adjuvant radiotherapy is controversial in the literature.

Occlusive radiation cerebral vasculopathy implies medical complexity: a case report

Background

Cranial irradiation is one of the main treatment modalities for central nervous system tumors. It carries many complications, one being occlusive radiation vasculopathy of large vessels. It is an underrecognized etiology for stroke, especially in the younger population. The pathophysiological process is controversial, but there is much literature supporting the theory of its being a secondary form of moyamoya disease.

Case presentation

A 31-year-old Caucasian man with a history of pineal blastoma at the age of 3 years, which was treated with resection, radiotherapy, and chemotherapy, presented to our institution with right M1 stroke. Further assessment by computed tomographic perfusion study with acetazolamide demonstrated steal phenomenon of the right middle cerebral artery territory (type III response) with a small internal region of matched cerebral blood volume defect (that is, infarct core). Coincidentally, he was found to have multiple brain masses consistent with meningiomas. Occlusive radiation vasculopathy was the most likely culprit of the patient’s stroke. The patient was treated medically with “baby” acetylsalicylic acid and clopidogrel for 3 months, then continued only on baby acetylsalicylic acid.

Conclusion

Late-onset occlusive radiation vasculopathy is a potentially severe iatrogenic manifestation of radiotherapy that requires a high index of suspicion as an etiology of stroke in young population, especially those with coexistent meningioma that might be a strong indicator for occlusive radiation vasculopathy as the stroke culprit. We reviewed the available literature to better understand the pathogenesis, clinical presentation, and treatment options of occlusive radiation vasculopathy. Applying perfusion studies with acetazolamide measures the cerebrovascular reserve in patients with occlusive radiation vasculopathy, which could help in determining the appropriate available treatment option.

Long-Term Outcomes for Pediatric Patients with Brain Arteriovenous Malformations Treated with Gamma Knife Radiosurgery, Part 2: The Incidence of Cyst Formation, Encapsulated Hematoma, and Radiation-Induced Tumor

OBJECTIVE

Long-term data about the incidence of late adverse radiation effects (AREs) in pediatric brain arteriovenous malformations (AVMs) treated with Gamma Knife radiosurgery (GKRS) are lacking. This study addresses the incidence of late AREs, including cyst formation (CF), chronic encapsulated hematoma (CEH), and radiation-induced tumor, in pediatric patients with AVM treated with GKRS.

METHODS

This is a single-institutional study involving pediatric patients with AVM who underwent GKRS between 1991 and 2014. Among 201 pediatric patients with AVM (age ≤15 years), 189 who had at least 12 months of follow-up were assessed in this study. The median treatment volume was 2.2 cm³, and the median marginal dose was 20 Gy.

RESULTS

The mean follow-up period was 136 months. During the follow-up period, symptomatic radiation-induced perilesional edema was found in 5 patients (3%), CFs in 7 patients (4%), CEHs in 7 patients (4%), and radiation-induced tumors in 2 patients (1%). The cumulative incidences of late AREs including CF, CEH, and radiation-induced tumor were 1.2% at 5 years, 5.2% at 8 years, 6.1% at 10 years, 7.2% at 15 years, and 17.0% at 20 years. In the multivariate analysis, treatment volume alone was a significant factor for late AREs (P < 0.001; hazard ratio, 1.111).

CONCLUSIONS

GKRS is a reasonable treatment option for pediatric AVMs to prevent future intracranial hemorrhages, particularly in the eloquent regions. However, considerable attention should be paid to late AREs such as CFs, CEHs, and radiation-induced tumors because of longer life expectancy in pediatric patients.

Meningiomas in pregnancy: timing of surgery and clinical outcomes as observed in 104 cases and establishment of a best management strategy

BACKGROUND

There is a strong correlation between the level of circulating female sex hormones and the parturient growth of meningiomas. As a result, rapid changes in meningioma size occur during pregnancy, putting both the mother and fetus at risk. Large, symptomatic meningiomas require surgical resection, regardless of the status of pregnancy. However, the preferred timing of such complex intervention is a matter of debate. The rarity of this clinical scenario and the absence of prospective trials make it difficult to reach evidence-based conclusions. The aim of this study was to create evidence-based management guidelines for timing of surgery for pregnancy-related intracranial meningiomas.

METHOD

The English literature from 1990 to 2016 was systematically reviewed according to PRISMA guidelines for all surgical cases of pregnancy-related intracranial meningiomas. Cases were divided into two groups: patients who have had surgery during pregnancy and delivered thereafter (group A) and patients who delivered first (group B). Groups were compared for demographic, clinical and radiological features, as well as for neurosurgical, obstetrical and neonatological outcomes. Statistical analysis was performed to assess differences.

RESULTS

A total of 104 surgical cases were identified and reviewed, of which 86 were suitable for comparison and statistical analysis. Thirty-five patients (40%) underwent craniotomy for resection during pregnancy or at delivery (group A) and 51 patients (60%) underwent surgery after delivery (group B). Groups showed no significant differences in characteristics such as age at diagnosis, number of gestations, presenting symptoms, tumor site and tumor size. Despite a comparable distribution over the gestational trimesters, group A had significantly more patients diagnosed prior to the 27th gestational week (46 vs 17.5%, p = 0.0075). Group A was also associated with a significantly higher rate of both emergent craniotomies (40 vs 19.6%, p = 0.0048) and emergent Caesarian deliveries (47 vs 17.8%, p = 0.00481). The time from diagnosis to surgery was significantly longer in group B (11 weeks vs 1 week in group A, p = 0.0013). The rate of premature delivery was high but similar in both groups (∼70%). Risks of maternal mortality or fetal mortality were associated with group A (odds ratio = 14.7), but did not reach statistical significance.

CONCLUSIONS

While surgical resection of meningioma during pregnancy may be associated with increased maternal and fetal mortalities, the overall neurosurgical, obstetrical and neonatological outcomes, as well as many clinical characteristics, are similar to patients undergoing resection postpartum. We believe that fetal survival chances have a significant impact on decision-making, as patients diagnosed at a later stage in pregnancy (≥27th week of gestation) were more likely to undergo delivery first. This complicated clinical scenario requires the close cooperation of multiple disciplines. While the mother's health and well-being should always be paramount in guiding management, we hope that the overall good outcomes observed by this systematic review will encourage colleagues to aim for term pregnancies whenever possible in order to reduce prematurity-related problems.

Medulloblastoma therapy generates risk of a poorly-prognostic H3 wild-type subgroup of diffuse intrinsic pontine glioma: a report from the International DIPG Registry

With improved survivorship in medulloblastoma, there has been an increasing incidence of late complications. To date, no studies have specifically addressed the risk of radiation-associated diffuse intrinsic pontine glioma (DIPG) in medulloblastoma survivors. Query of the International DIPG Registry identified six cases of DIPG with a history of medulloblastoma treated with radiotherapy. All patients underwent central radiologic review that confirmed a diagnosis of DIPG. Six additional cases were identified in reports from recent cooperative group medulloblastoma trials (total n = 12; ages 7 to 21 years). From these cases, molecular subgrouping of primary medulloblastomas with available tissue (n = 5) revealed only non-WNT, non-SHH subgroups (group 3 or 4). The estimated cumulative incidence of DIPG after post-treatment medulloblastoma ranged from 0.3-3.9%. Posterior fossa radiation exposure (including brainstem) was greater than 53.0 Gy in all cases with available details. Tumor/germline exome sequencing of three radiation-associated DIPGs revealed an H3 wild-type status and mutational signature distinct from primary DIPG with evidence of radiation-induced DNA damage. Mutations identified in the radiation-associated DIPGs had significant molecular overlap with recurrent drivers of adult glioblastoma (e.g. NRAS, EGFR, and PTEN), as opposed to epigenetic dysregulation in H3-driven primary DIPGs. Patients with radiation-associated DIPG had a significantly worse median overall survival (median 8 months; range 4-17 months) compared to patients with primary DIPG. Here, it is demonstrated that DIPG occurs as a not infrequent complication of radiation therapy in survivors of pediatric medulloblastoma and that radiation-associated DIPGs may present as a poorly-prognostic distinct molecular subgroup of H3 wild-type DIPG. Given the abysmal survival of these cases, these findings provide a compelling argument for efforts to reduce exposure of the brainstem in the treatment of medulloblastoma. Additionally, patients with radiation-associated DIPG may benefit from future therapies targeted to the molecular features of adult glioblastoma rather than primary DIPG.

MR imaging findings in some rare neurological complications of paediatric cancer

Abstract

Neurological complications of paediatric cancers are a substantial problem. Complications can be primary from central nervous system (CNS) spread or secondary from indirect or remote effects of cancer, as well as cancer treatments such as chemotherapy and radiation therapy. In this review, we present the clinical and imaging findings of rare but important neurological complications in paediatric patients with cancer. Neurological complications are classified into three phases: pre-treatment, treatment and post-remission. Paraneoplastic neurological syndromes, hyperviscosity syndrome, haemophagocytic lymphohistiocytosis and infection are found in the pre-treatment phase, while Trousseau’s syndrome, posterior reversible encephalopathy syndrome and methotrexate neurotoxicity are found in the treatment phase; though some complications overlap between the pre-treatment and treatment phases. Hippocampal sclerosis, radiation induced tumour, radiation induced focal haemosiderin deposition and radiation-induced white matter injury are found in the post-remission phase. With increasingly long survival after treatment, CNS complications have become more common. It is critical for radiologists to recognise neurological complications related to paediatric cancer or treatment. Magnetic resonance imaging (MRI) plays a significant role in the recognition and proper management of the neurological complications of paediatric cancer.

Teaching Points

• Neurological complications of paediatric cancer include various entities.

• Neurological complications are classified into three phases: pre-treatment, treatment and post-remission.

• Radiologists should be familiar with clinical and imaging findings of neurological complications.

• MRI features may be characteristic and lead to early diagnosis and proper treatments.

Irradiation-Induced Secondary Tumors following Pediatric Central Nervous System Tumors: Experiences of a Single Institute in Taiwan (1975-2013)

PURPOSE

Complications can occur following a prolonged latency period after radiation therapy for cancer, and this is a growing concern because secondary tumors are potentially fatal. Few studies have examined secondary tumors in patients who received radiation therapy as children.

METHODS AND MATERIALS

This retrospective study examined 1697 pediatric patients with central nervous system tumors who received treatment at Taipei Veterans General Hospital from January 1, 1975, to December 31, 2013. Secondary tumors developed in 27 of 681 patients who received cranial irradiation. Overall survival was estimated using the Kaplan-Meier method, and the significance of differences was determined by the log-rank test.

RESULTS

The overall cumulative incidence of secondary tumors at 25 years was 3.96%, and there were similar numbers of male patients (n = 16) and female patients (n = 11). The mean age at diagnosis was 8.8 years (range, 3-16.5 years), the median dose of cranial irradiation was 52.5 Gy (mean, 53.4 Gy), the mean latency period was 14.6 years (range, 2-33 years), and the mean age at diagnosis of a secondary tumor was 23.1 years. The secondary tumors were mainly meningiomas (n = 13), sarcomas (n = 7), and high-grade gliomas (n = 6), and the mean latency periods were 19.66, 8.00, and 10.83 years, respectively. The overall survival rate from these secondary tumors was significantly different (P < .05). Age at irradiation of <7 years and craniospinal irradiation significantly increased the risk of a secondary tumor (P < .05). Secondary tumors developed in 11 of 128 patients (8.6%) with primary medulloblastomas, which was higher than the overall cumulative incidence.

CONCLUSIONS

Clinicians should consider the increased risk of secondary tumors in long-term cancer survivors who received craniospinal irradiation as children. Using a selective dose de-escalation strategy or deferring radiation therapy for young patients at highest risk of secondary cancers should be studied.

Malignant Gliomas as Second Neoplasms in Pediatric Cancer Survivors: Neuropathological Study

This study presents a unique series of malignant supratentorial gliomas in children previously cured from non-CNS primary cancer. On neuroimaging these tumors were not specific, so the patients were suspected of cerebral recurrence of their primary neoplasm: leukemia in four children and sarcoma in one child. Histologically, the group contained four glioblastomas and one anaplastic astrocytoma. Three patients underwent neurosurgical resection, while the other two underwent stereotactic diagnostic biopsy only. Despite combined oncological treatment, four children died during 20 months, and only one glioblastoma patient continued to live for another twelve years. Microscopically, the neoplasms consisted of small cells with some morphologic features of astrocytic lineage, having scanty or prominent processes. Microvascular proliferation and focal or diffuse necrosis were encountered in four cases. The GFAP reactivity in neoplastic cells was low or nil, together with the expression of Olig2, vimentin, and nestin. In two cases a subpopulation of synaptophysin-positive cells was present. Molecular immunohistochemical profiling revealed the expression of phosphorylated forms of PI3Kp110 and AKT, in parallel to a strong PTEN and p53 positivity. The tumors were of IDH1R132H-wild type and immunoreactive for ATRX, HER3, and EGFR. Secondary malignant gliomas in pediatric cancer survivors pose a diagnostic challenge. The present study shows that these tumors are of IDH wild type, PI3K/AKT-activated, having no PTEN and EGFR mutations. Therefore, the biopsy of brain tumors in such patients is crucial both for accurate diagnosis and material preservation for molecular typing.

Coexistence of Radiation-Induced Meningioma and Moyamoya Syndrome 10 Years after Irradiation against Medulloblastoma: a Case Report

Radiotherapy is one of the standard treatments for medulloblastoma. However, therapeutic central nervous system irradiation in children may carry delayed side effects, such as radiation-induced tumor and vasculopathy. Here, we report the first case of coexisting meningioma and moyamoya syndrome, presenting 10 years after radiotherapy for medulloblastoma. A 13-year-old boy presented with an enhancing mass at the cerebral falx on magnetic resonance imaging (MRI) after surgery, radiotherapy (30.6 Gy craniospinal axis, 19.8 Gy posterior fossa) and chemotherapy against medulloblastoma 10 years ago, previously. The second tumor was meningioma. On postoperative day 5, he complained of right-sided motor weakness, motor dysphasia, dysarthria, and dysphagia. MRI revealed acute cerebral infarction in the left frontal lobe and both basal ganglia. MR and cerebral angiography confirmed underlying moyamoya syndrome. Four months after the meningioma surgery, the patient presented with headaches, dysarthria, and dizziness. Indirect bypass surgery was performed. He has been free from headaches since one month after the surgery. For patients who received radiotherapy for medulloblastoma at a young age, clinicians should consider the possibility of the coexistence of several complications. Careful follow up for development of secondary tumor and delayed vasculopathy is required.

A coordinated DNA damage response promotes adult quiescent neural stem cell activation

Stem and differentiated cells frequently differ in their response to DNA damage, which can determine tissue sensitivity. By exploiting insight into the spatial arrangement of subdomains within the adult neural subventricular zone (SVZ) in vivo, we show distinct responses to ionising radiation (IR) between neural stem and progenitor cells. Further, we reveal different DNA damage responses between neonatal and adult neural stem cells (NSCs). Neural progenitors (transit amplifying cells and neuroblasts) but not NSCs (quiescent and activated) undergo apoptosis after 2 Gy IR. This response is cell type- rather than proliferation-dependent and does not appear to be driven by distinctions in DNA damage induction or repair capacity. Moreover, exposure to 2 Gy IR promotes proliferation arrest and differentiation in the adult SVZ. These 3 responses are ataxia telangiectasia mutated (ATM)-dependent and promote quiescent NSC (qNSC) activation, which does not occur in the subdomains that lack progenitors. Neuroblasts arising post-IR derive from activated qNSCs rather than irradiated progenitors, minimising damage compounded by replication or mitosis. We propose that rather than conferring sensitive cell death, apoptosis is a form of rapid cell death that serves to remove damaged progenitors and promote qNSC activation. Significantly, analysis of the neonatal (P5) SVZ reveals that although progenitors remain sensitive to apoptosis, they fail to efficiently arrest proliferation. Consequently, their repopulation occurs rapidly from irradiated progenitors rather than via qNSC activation.

The response of stem cells to DNA damage is poorly understood, although there is increasing evidence that they respond distinctly to differentiated cells. We have monitored the different responses of adult neural stem and progenitor cells to exposure to X-ray irradiation. We see that progenitor cells activate apoptosis, undergo rapid proliferation arrest, and premature differentiation. However, quiescent stem cells do not activate radiation-induced apoptosis. Instead the responses of the progenitor cells promote the activation of these quiescent neural stem cells, thereby replenishing the neuroblasts. These responses and quiescent stem cell activation are dependent on the ataxia telangiectasia mutated (ATM) kinase. We propose that this coordinated response functions to remove damaged progenitor cells and to aid repopulation.

Pediatric high-grade glioma: current molecular landscape and therapeutic approaches

High-grade pediatric central nervous system glial tumors are comprised primarily of anaplastic astrocytomas (AA, WHO grade III) and glioblastomas (GBM, WHO grade IV). High-grade gliomas are most commonly diagnosed in the primary setting in children, but as in adults, they can also arise as a result of transformation of a low-grade malignancy, though with limited frequency in the pediatric population. The molecular genetics of high-grade gliomas in the pediatric population are distinct from their adult counterparts. In contrast to the adult population, high-grade gliomas in children are relatively infrequent, representing less than 20% of cases.

MR imaging of brain pilocytic astrocytoma: beyond the stereotype of benign astrocytoma

BACKGROUND

Pilocytic astrocytoma (PA) is the most common pediatric brain glioma and is considered the prototype of benign circumscribed astrocytoma. Despite its low malignancy, the CT and MRI features of brain PA may resemble those of much more aggressive brain tumors. Misdiagnosis of PA is particularly easy when it demonstrates MR morphological and non-morphological findings that are inconsistent with its non-aggressive nature and that overlap with the features of more aggressive brain tumors.

METHOD

Basing on the evidence that the variation in the histological, genetic, and metabolic "fingerprint" for brain PA is dependent on tumor location, and the hypothesis that tumor location is related to the broad spectrum of morphological and non-morphological MR imaging findings, the authors discuss the MR imaging appearance of brain PA using a location-based approach to underline the typical and less typical imaging features and the main differential diagnosis of brain PA. A brief summary of the main pathological and clinical features, the natural history, and the treatment of brain PA is also provided.

RESULT

A combination of morphological and non-morphological MR imaging features and a site-based approach to differential diagnosis are required for a pre-operative diagnosis. The new "cutting-edge" MR imaging sequences have the potential to impact the ease and confidence of pediatric brain tumor interpretation and offer a more efficient diagnostic work-up.

CONCLUSIONS

Although the typical imaging features of brain pilocytic astrocytoma make radiological diagnosis relatively easy, an atypical and more aggressive appearance can lead to misdiagnosis. Knowing the broad spectrum of imaging characteristics on conventional and advanced MR imaging is important for accurate pre-operative radiological diagnosis and correctly interpreting changes during follow-up.

Radiation-Induced Meningiomas: An Exhaustive Review of the Literature

OBJECTIVE

Radiation-induced meningioma (RIM) is an uncommon late risk of cranial irradiation. We conducted an exhaustive review of individual patient data to characterize RIM.

METHODS

Using a systematic search of the PubMed database, we performed a comprehensive literature review to characterize and investigate RIM. Student t tests were used to evaluate differences between variables. A Kaplan-Meier analysis was used to assess survival. Statistical significance was assessed using a log-rank test.

RESULTS

Our analysis included 251 cases of RIM. The average age at onset for the primary lesion was 13.0 ± 13.5 years, and the average radiation dose delivered to this lesion was 38.8 ± 16.8 Gy. Secondary meningiomas could be divided into grades I (140), II (55), and III (10) tumors. Thirty patients (11.9%) had multiple lesions, and 46 (18.3%) had recurrent meningiomas. The latency period between radiotherapy for primary lesions and the onset of meningiomas was 22.9 ± 11.4 years. The latency period was shorter for patients with grade III meningioma and for those in the high-dose and intermediate-dose radiation groups who received systemic chemotherapy. Aggressive meningiomas and multiple meningiomas were more common in the high-dose and intermediate-dose groups than in the low-dose group. The 5-year and 10-year survival rates for all patients with meningioma were 77.7% and 66.1%, respectively.

CONCLUSIONS

For patients treated with cranial radiotherapy, the risk of secondary meningioma warrants a longer follow-up period beyond the standard time frame typically designated for determining the risk of primary tumor relapse.

Secondary Solid Malignancies After High-Grade Glioma Treatment in Pediatric Patients

Due to the poor survival in high-grade glioma (HGG), secondary solid malignancies (SSM) following pediatric HGG are scarce. The authors present the experience from the HIT-HGG database in Germany, Austria, and Switzerland. Five out of 1228 pediatric HGG patients developed a SSM following a latency of 29-122 months from primary HGG diagnosis. In 4 patients, the SSM may be attributed to previous radiotherapy or a tumor predisposition syndrome, reflected by a markedly increased cumulative incidence rate of SSM in patients with tumor predisposition. Survival was devastating, since none of the patients survived beyond 18 months from SSM diagnosis.

In vivo sensitivity of the embryonic and adult neural stem cell compartments to low-dose radiation

The embryonic brain is radiation-sensitive, with cognitive deficits being observed after exposure to low radiation doses. Exposure of neonates to radiation can cause intracranial carcinogenesis. To gain insight into the basis underlying these outcomes, we examined the response of the embryonic, neonatal and adult brain to low-dose radiation, focusing on the neural stem cell compartments. This review summarizes our recent findings. At E13.5-14.5 the embryonic neocortex encompasses rapidly proliferating stem and progenitor cells. Exploiting mice with a hypomorphic mutation in DNA ligase IV (Lig4(Y288C) ), we found a high level of DNA double-strand breaks (DSBs) at E14.5, which we attribute to the rapid proliferation. We observed endogenous apoptosis in Lig4(Y288C) embryos and in WT embryos following exposure to low radiation doses. An examination of DSB levels and apoptosis in adult neural stem cell compartments, the subventricular zone (SVZ) and the subgranular zone (SGZ) revealed low DSB levels in Lig4(Y288C) mice, comparable with the levels in differentiated neuronal tissues. We conclude that the adult SVZ does not incur high levels of DNA breakage, but sensitively activates apoptosis; apoptosis was less sensitively activated in the SGZ, and differentiated neuronal tissues did not activate apoptosis. P5/P15 mice showed intermediate DSB levels, suggesting that DSBs generated in the embryo can be transmitted to neonates and undergo slow repair. Interestingly, this analysis revealed a stage of high endogenous apoptosis in the neonatal SVZ. Collectively, these studies reveal that the adult neural stem cell compartment, like the embryonic counterpart, can sensitively activate apoptosis.

A successful case of an anaplastic meningioma treated with chemotherapy for soft tissue sarcomas

Malignant meningioma has a bad prognosis. Surgery and radiotherapy are the most effective therapeutic options, without an established role for chemotherapy. We report a case of 2-year-old male child with diagnosis of postoperative relapse of a malignant meningioma. Considering the rapid progression, the young age and the lack of effective therapeutic alternatives, the patient underwent multidisciplinary anticancer treatment with a protocol made for soft tissue sarcomas (EpSSG NRSSTS 2005 protocol), with positive outcome. This case represents a successful management of an anaplastic meningioma with a multimodal treatment, including chemotherapy, in a pediatric patient.

Rare case of radiation-induced trigeminal schwannoma occurring in a long-term glioblastoma multiforme survivor

Glioblastoma multiforme (GBM) is a high-grade primary brain tumour with a notably poor prognosis. Research demonstrates a median survival of just over 1 year following aggressive treatment. Long-term survival is notably rare. Cranial radiotherapy and postexcisional prophylactic treatment is associated with the development of second, histologically distinct tumours in rare cases. Radiation-induced intracranial schwannomas are uncommon, with only a small number of cranial nerve schwannoma cases reported in recent decades. To our knowledge, this is the first reported case of a radiation-induced benign trigeminal schwannoma occurring following long-term survival from glioblastoma. Here we present (1) a rare case of 14-year survival following treatment of a right parietal glioblastoma and the development of a radiation-induced benign trigeminal schwannoma in a 35-year-old man, and (2) a review of radiation-induced schwannoma cases reported in the existing literature.

Prolactinoma associated with an ependymoma in the fourth ventricle: A case report and review of the literature

Pituitary adenoma associated with ependymoma in the fourth ventricle is a rare condition. In the present study, a 46-year-old man diagnosed with prolactinoma, who previously underwent two surgical procedures (one for the removal of a primary tumor and a second following its recurrence) developed a complication of ependymoma in the fourth ventricle. The presence of the ependymoma was confirmed by pathological analysis and the patient recovered well following two-phase surgical resection of the two tumors. The present study compared the probable cause of concurrent pituitary adenoma and ependymoma within the fourth ventricle with previous relevant studies. These comparisons were used to propose possible genomic and endocrine contributions for the development of the ependymoma from the pituitary adenoma.

De novo formation of brain tumors in pediatric population following therapeutic cranial irradiation

PURPOSE

Tumors of central nervous system (CNS) are accounted as the second most common tumors in childhood (21% of all cancers) following hematologic malignancies. The patients can suffer more than one cancer in their lifetime, and radiotherapy is claimed for de novo formation of a new tumor in years after treatment of an initial tumor.

METHODS

We have retrospectively analyzed our database for defining radiotherapy-related de novo brain tumors operated in between January, 2000 and August, 2012. New tumors in the field of radiotherapy were included into the study.

RESULTS

The retrospective analysis revealed six patients (two girls and four boys) eligible for further evaluation. The children were irradiated at an age in the range of 5 and 12 years (mean, 7.8). The primary diagnoses were hematological malignancies in two (acute lymphocytic leukemia and non-Hodgkin lymphoma (NHL)) and solid tumors in other four (two pilocytic astrocytoma, one craniopharyngioma, and one grade 3 astrocytoma). All patients received cranial radiotherapy. The mean latency period for the "second tumor" was 9.5 years. The pathological diagnoses for de novo new tumors were as follows: glial tumor (two cases), medulloblastoma (two cases), mesenchymal tumor (one case), and meningeal sarcoma (one case). All de novo tumors were high graded. Mean survival was 14.6 months.

CONCLUSIONS

de novo brain tumors after irradiation has poor prognosis in neurosurgical practice. Vigilance and awareness for possibility of de novo new tumor are warranted for both families and physicians at follow-ups even years after the treatment of initial tumors.

Volumetric modulated arc therapy versus 3D conformal radiotherapy for selected childhood neoplasms

Aim

The comparative study of the plan quality between volumetric modulated arc therapy (VMAT) and 3D conformal therapy (3DCRT) for the treatment of selected representative childhood neoplasms was performed.

Materials and methods

During the year 2013, 44 children with neoplasms were irradiated using VMAT. The 3DCRT plans were created retrospectively and compared with the VMAT plans for four tumour locations. The conformity parameters, dose volume histograms for target volume and organs at risk, number of monitor units and time used to deliver the single fraction were evaluated and compared for each plan. Additionally, for patients with brain tumour the comparison of different arcs configuration was made.

Results

VMAT modality presented the superiority over older conformal methods with regard to the improvement in the dose conformity and normal tissue sparing. The noncoplanar arcs arrangement was beneficial in the decrease of high-dose volume and the protection of the organs at risk located oppositely to the target volume.

Findings

VMAT could be preferred technique for treating childhood neoplasms, especially when the complex-shaped target volume is localised close to the critical structures. The noncoplanar arcs arrangement could be the method of choice in the reirradiated patients and in these with laterally located brain tumours.

Meningiomas of the pediatric skull base: a review

Pediatric skull base meningiomas are rare and complex clinical entities. Meningioma is a relatively uncommon brain tumor in children, and only ∼ 27% involve the skull base. Some evidence suggests that these tumors are more likely to be atypical or malignant in children than adults. The absence of female preponderance in pediatric meningiomas is reflected in the skull base subpopulation. Skull base meningiomas in children are most likely to be found in the anterior or middle fossa base, or involving the orbit and optic nerve sheath. Petroclival, suprasellar/parasellar, cerebellopontine angle, cavernous sinus, and foramen magnum tumors are very rare. Meningiomas constitute a small proportion of reported cases of pediatric skull base pathology, and they are entirely absent from many case series. Initial gross total resection is consistently associated with superior outcomes. Surgical approaches to the pediatric skull base must take additional factors into consideration including relatively smaller anatomy, immature dentition, incompletely aerated sinuses and air cells, and altered configurations of structures such as the pterional bony complex. Multidisciplinary expertise is essential to optimizing treatment outcomes.