Paediatric brain tumours

• Primary brain tumours are the commonest solid tumours of childhood and remain the leading cause of cancer-related death among children; they account for roughly one-quarter of paediatric cancers. ^[1][2]
• Most childhood brain tumours sit in the posterior fossa or along midline structures, so they declare themselves early through raised intracranial pressure: morning headache, vomiting, gait unsteadiness and papilloedema.
• The three classic posterior fossa tumours of childhood are medulloblastoma, pilocytic astrocytoma and ependymoma; each has a different site, imaging appearance and biology, which determines treatment and prognosis.
• Supratentorial and brainstem tumours have their own patterns: low-grade glial tumours and germ cell tumours often respect midline structures, whereas diffuse midline glioma is aggressive from the outset.
• Management rests on careful pre-operative control of raised pressure, maximal safe surgery, risk-adapted radiotherapy where anatomy allows, chemotherapy and, increasingly, molecularly targeted therapy.
• Many children now survive these tumours, so modern care also means planning long-term follow-up for endocrine, neurocognitive, auditory and vascular late effects. ^[7]

By the end of this page you should be able to:

1. Describe why a posterior fossa tumour in a child produces the classic symptoms and signs of raised intracranial pressure, and identify the emergency it creates.
2. Distinguish medulloblastoma, pilocytic astrocytoma and ependymoma by age, site, imaging and histology, and explain how this changes management.
3. Recognise a brainstem or diffuse midline glioma clinically and explain why surgery is not curative.
4. Interpret germ cell tumour markers and the imaging pattern of a bifocal lesion, and outline the treatment of germinoma and non-germinomatous tumours.
5. Apply the principles of risk-adapted radiotherapy and chemotherapy in medulloblastoma, and the role of surgery and targeted therapy in paediatric low-grade glioma.
6. List the late effects that survivors of childhood brain tumour are at risk of, and the measures used to reduce them.

A primary paediatric brain tumour is a neoplasm arising from the brain, its coverings or the ventricular system in a child or adolescent. This page uses the term in that restricted sense, which excludes metastatic disease and the common extra-axial tumours of the skull base. The tumours behave very differently from adult brain tumours: most are in the posterior fossa or along midline structures rather than in the cerebral hemispheres, and many carry a molecular signature that is almost never seen in adults.

The current World Health Organization (WHO) classification of central nervous system tumours (2021, fifth edition) combines microscopic appearance with molecular alterations. In practice, the paediatric brain tumours that matter day to day fall into five groups:

• Embryonal tumours, of which medulloblastoma is the most common malignant primary brain tumour of childhood. ^[1]
• Low-grade glial tumours, mainly the pilocytic astrocytoma of the cerebellum, optic pathways and brainstem, together with diffuse astrocytic gliomas.
• Ependymomas, which arise from the walls of the ventricular system and, in children, most often from the floor of the fourth ventricle.
• Gliomas of the brainstem and midline, including focal low-grade lesions and diffuse midline glioma, an aggressive entity defined by alteration of histone H3 at lysine 27.
• Germ cell tumours, clustered in the pineal and suprasellar regions and frequent in adolescents and young adults.

Histological grade is not the whole story. A cerebellar pilocytic astrocytoma is WHO grade 1 yet can behave badly if it blocks the ventricles; a diffuse midline glioma is grade 4 in function if not in every microscopic field. This is why treatment is decided by the whole package of age, site, grade and molecular profile, not by grade alone.

Primary brain tumours are the most common solid tumours of childhood, and in most series they remain the leading cause of cancer-related death in children. ^[2] The incidence is approximately 6 new cases per 100,000 person-years, and more than 4,000 brain and spinal cord tumours are diagnosed each year in children and teenagers in the United States alone; together they account for about one-quarter of all childhood cancers. ^[1]

Survival has improved, but not evenly. Medulloblastoma carries a long-term survival that is described as variable rather than uniformly poor, whereas diffuse midline glioma remains a disease with a median survival measured in months. ^[1][8] Pilocytic astrocytomas, in contrast, have prolonged survival, and paediatric low-grade gliomas as a whole are increasingly managed as a chronic disease because patients live for decades. ^[6]

Some types are strongly regional. Intracranial germ cell tumours form only 1 to 3 percent of paediatric brain tumours in North America and Europe, but 8 to 15 percent in East Asia, and the persistence of this difference in migrant populations argues for an inherited susceptibility. ^[4]

For most children with a brain tumour, no identifiable cause is found. The recognised associations are few but important:

• Ionising radiation to the head, including therapeutic radiation for leukaemia or tinea capitis, is the clearest environmental risk factor, with tumours sometimes appearing years later.
• Tumour predisposition syndromes: neurofibromatosis type 1 (optic pathway and brainstem gliomas), tuberous sclerosis (subependymal giant cell astrocytoma), Li-Fraumeni syndrome (high-grade gliomas), Turcot syndrome and Cowden syndrome. Children with an unusually early onset, multiple tumours or a relevant family history should be assessed for an underlying syndrome.
• Familial clustering is modest for most types. Intracranial germ cell tumours are the exception noted above.
• There is no convincing evidence that mobile telephones, power lines or dietary factors cause childhood brain tumours.

The paediatric skull has limited room to expand, and the posterior fossa is the smallest and most rigid compartment. A tumour there needs only to be a few centimetres across before it obstructs the fourth ventricle or the cerebral aqueduct, blocking cerebrospinal fluid (CSF) circulation and producing obstructive hydrocephalus. The pressure inside the skull (intracranial pressure, ICP) then rises, and the earliest symptoms are those that occur on waking: morning headache that improves upright during the day, and vomiting without preceding nausea. A baby may show a bulging fontanelle, a rapidly increasing head circumference, irritability and downward deviation of the eyes (the setting-sun sign). Straining, coughing or changes in posture can worsen the headache because they create transient spikes of pressure.

The same mass effect explains the focal signs. The cerebellum controls coordination, so vermian or hemispheric tumours produce truncal unsteadiness, an unsteady wide-based gait, intention tremor, dysmetria on the finger-nose test and nystagmus. Cranial nerves VI and VII are stretched by posterior fossa mass effect and cause diplopia and facial weakness. The brainstem houses cranial nerve nuclei, long motor and sensory tracts and the centres that control breathing and swallowing, so a tumour there produces crossed findings: cranial nerve palsies on one side and limb weakness on the other, with dysarthria and dysphagia. Supratentorial tumours can present with seizures, progressive hemiparesis, visual field defects (bitemporal hemianopia from optic chiasm compression) or changes in behaviour and school performance.

Raised ICP is a medical emergency when it is accompanied by drowsiness, repeated vomiting, a dilated or poorly reactive pupil, or abnormal posturing, because the brainstem can herniate through the foramen magnum. A fundoscopic examination for papilloedema is therefore essential in any child with a persistent new headache, and the child with suspected raised pressure should be kept upright, fasted, and imaged without a delay for an elective appointment.

• Headache, characteristically worse in the morning and worsened by coughing, straining or bending.
• Vomiting, often without preceding nausea and sometimes projectile.
• Behavioural or school decline, personality change or new clumsiness.
• Squint, diplopia or nystagmus.
• Macrocephaly and a bulging fontanelle in infants.

• Cerebellar vermian tumour (medulloblastoma or ependymoma): unsteady gait and truncal ataxia may precede headache; the child may refuse to walk.
• Cerebellar hemispheric tumour: ipsilateral limb ataxia and headache.
• Pineal region tumour: Parinaud syndrome (upward gaze palsy, convergence-retraction nystagmus, lid retraction), early hydrocephalus.
• Suprasellar tumour: poor growth, diabetes insipidus (polyuria and polydipsia), precocious puberty or arrested puberty, visual failure.
• Brainstem tumour: isolated or crossed cranial nerve palsies, facial weakness or numbness, dysarthria and dysphagia, a long tract pattern, sometimes with surprisingly mild headache early on.
• Hypothalamic tumour: diencephalic syndrome in infants (failure to thrive with apparent well-being), or obesity and sleep disturbance in older children.

The first distinction is tumour from non-tumour causes of raised pressure: idiopathic intracranial hypertension (rare in children under puberty; associated with obesity in adolescents and with papilloedema but a normal scan), hydrocephalus from aqueduct stenosis or a choroid plexus papilloma, cerebral venous sinus thrombosis (otogenic, with a history of ear infection) and meningoencephalitis. The second distinction, once a mass is seen, is to place the tumour among the common entities.

Adult gliomas, metastases and lymphoma are uncommon in children and are not considered unless the age or history makes them plausible. When two intracranial masses are seen in the same child, think of neurofibromatosis or multiple metastases only if the imaging is atypical.

Magnetic resonance imaging (MRI) of the brain and spine with gadolinium contrast is the study of choice. It shows the site, size, cystic or solid nature, hydrocephalus and spinal drop metastases. A computed tomography (CT) scan of the head is faster and is used in an emergency to exclude haemorrhage and hydrocephalus while MRI is arranged; it also detects calcification in tumours such as craniopharyngioma and teratoma. In children, whenever possible, imaging should be performed with age-appropriate sedation and paediatric anaesthesia, and the radiologist should comment specifically on whether the tumour is resectable.

A neuro-ophthalmology examination, endocrine assessment (growth velocity, thyroid and gonadal axes, serum and urine osmolality) and developmental assessment are needed before treatment is planned, because they document the baseline against which later deficits will be measured.

For a lesion that could be a germ cell tumour, serum and CSF alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (beta-hCG) must be measured in both compartments before any surgery or chemotherapy, because the result determines both diagnosis and treatment.

Two caveats are essential. First, germinomas are usually marker-negative but a subset secretes low-level beta-hCG from syncytiotrophoblasts, so a mildly elevated beta-hCG does not by itself make a tumour non-germinomatous. Second, serum and CSF markers can disagree, and markers below the diagnostic thresholds do not exclude disease: roughly two-thirds of patients still need a biopsy because they are not diagnosable by markers alone. ^[4] When both serum and CSF AFP and beta-hCG are below the group thresholds and the imaging shows both pineal and suprasellar (bifocal) disease in a child over 8 to 10 years, major groups accept treatment as germinoma without biopsy; otherwise a biopsy is required. ^[4]

Staging determines risk group. For medulloblastoma it requires MRI of the whole craniospinal axis and CSF cytology to look for drop metastases. For germ cell tumours, metastatic disease is defined by positive CSF cytology or visible intracranial or spinal seeding on imaging; deposits seen only at an endoscopic procedure do not qualify, and a lumbar puncture should be performed two weeks after surgery for staging purposes. Bifocal pineal and suprasellar lesions are considered non-disseminated. ^[4]

Medulloblastoma is now classified by both histology and molecular profile. The four histological groups are classic, desmoplastic/nodular, medulloblastoma with extensive nodularity and large cell/anaplastic. The four molecular groups are WNT-activated, SHH-activated, group 3 and group 4. The molecular group carries more prognostic weight than histology. In the educational case review, five-year survival is given as above 90 percent for the WNT group, 70 percent for the SHH group, 40 percent for group 3, and 70 to 80 percent for group 4. Group 3 carries the worst prognosis through MYC amplification and metastasis. ^[1]

Red flags for a poor outcome in medulloblastoma are age under three years at diagnosis, residual tumour after surgery, anaplastic (large cell/anaplastic) histology and metastatic disease. ^[1]

Paediatric low-grade gliomas (pLGG) constitute the most common central nervous system neoplasm of childhood and account for roughly one-third of paediatric CNS tumours. ^[6] Many are indolent, and long-term survival is excellent, although the disease can have a prolonged course with repeated progression and cumulative morbidity. ^[6]

Diffuse midline glioma (DMG, historically diffuse intrinsic pontine glioma or DIPG) is the corresponding high-grade lesion. It predominantly affects children aged 5 to 10, is centred in the pons and is associated with a median overall survival of less than a year and a five-year survival below 1 percent. ^[8] Epidemiologically, about 20 to 30 new DIPG cases occur annually in the United Kingdom and 100 to 400 annually in the United States. ^[8] The 2021 WHO classification renamed the entity from "diffuse midline glioma, H3K27M-mutant" to "diffuse midline glioma, H3 K27-altered", to include a broader range of epigenetic change. ^[8]

• Keep the child upright and nil by mouth while imaging is arranged.
• Give a corticosteroid such as dexamethasone at a dose appropriate to body weight and clinical situation, to reduce vasogenic oedema, following local paediatric neuro-oncology practice.
• Add an osmotic agent (hypertonic saline or mannitol) only for acute neurological deterioration.
• Manage hydrocephalus: an external ventricular drain or an endoscopic third ventriculostomy is preferred over a lumbar puncture, which in obstructive hydrocephalus risks tonsillar herniation. A permanent ventriculoperitoneal shunt is often placed before or at the time of tumour resection in a child with hydrocephalus.
• Anticonvulsants are used only if there have been seizures; prophylactic anticonvulsants are not indicated.

Every child with a brain tumour should be managed by a paediatric neuro-oncology multidisciplinary team, with access to paediatric neurosurgery, paediatric anaesthesia, paediatric intensive care, neurology, endocrinology, neuropsychology and paediatric oncology. In this build, national guidelines such as NICE NG99 (brain tumours in people aged 16 and over) set standards for adult care and encourage the same multidisciplinary approach; paediatric patients in Europe and North America are entered into or managed alongside cooperative group protocols (SIOP-Europe and COG respectively). ^[3][4][5]

Surgery serves three purposes: to obtain a diagnosis, to relieve pressure, and to remove as much tumour as can be taken safely. The strongest prognostic modifier in most paediatric brain tumours is the extent of resection. Maximal safe resection is pursued for pilocytic astrocytoma and ependymoma, is an integral part of risk stratification in medulloblastoma (significant residual tumour places a child in a higher risk group), and is not applicable in diffuse midline glioma. In germ cell tumours, surgery is mainly diagnostic or for CSF diversion, with selected mature teratomas needing complete resection.

Cerebellar mutism, a striking syndrome of mutism and ataxia after posterior fossa surgery, occurs in a significant minority and should be discussed with the family before the operation.

Treatment is risk-adapted. After maximal safe resection and staging:

1. Standard-risk disease, in a child aged three years or more with no metastases and small residual: craniospinal irradiation with a posterior fossa boost, combined with concomitant and adjuvant chemotherapy.
2. High-risk disease, including age under three years, metastatic spread, significant residual tumour or anaplastic histology: intensified chemotherapy, a higher boost dose, and consolidation strategies. ^[1]

Infants under three years are the special problem, because craniospinal irradiation at that age causes severe neurocognitive injury. They are treated with surgery followed by prolonged multi-agent chemotherapy, with radiotherapy delayed, reduced or omitted where possible and added later in selected higher-risk disease. Chemotherapy for older children typically includes an alkylating agent, a platinum compound and a vinca alkaloid in rotation, with haematopoietic stem cell rescue in some protocols. ^[1][7]

Radiation dose and technique matter: modern practice uses conformal photon or proton craniospinal irradiation and a posterior fossa or tumour bed boost, with an aim of preserving as much of the cochlea and hypothalamic-pituitary axis as possible. ^[7][9]

Surgery alone can cure a cerebellar pilocytic astrocytoma when total resection is achieved. When a resection leaves residual tumour, many children remain stable for years, and active treatment is reserved for radiological or symptomatic progression, or for tumours threatening vision, the hypothalamus or the brainstem.

When chemotherapy is needed, the current standard of care in many centres is a carboplatin and vincristine regimen or vinblastine monotherapy, with five-year progression-free survival of 40 to 50 percent for either approach. ^[6] Visual impairment affects up to 80 percent of children with optic pathway or hypothalamic tumours, and the treated child is therefore a chronic disease patient requiring repeated therapy and visual rehabilitation. ^[6]

Molecularly targeted therapy has changed the outlook for selected subsets:

• BRAF V600E-mutant tumours: dabrafenib plus trametinib (a BRAF and MEK inhibitor pair) has demonstrated an objective response rate of about 47 percent versus 11 percent with chemotherapy, and is now used as first-line therapy in many centres. ^[6]
• BRAF-fusion (KIAA1549::BRAF) tumours: type I BRAF inhibitors can paradoxically activate signalling, so MEK inhibitors such as trametinib or tovorafenib are used instead, either as second-line therapy or in the first line in trials; tovorafenib has an objective response rate of about 51 percent. ^[6]
• NF1-associated tumours respond to selumetinib (a MEK inhibitor), which is approved for neurofibromatosis type 1 plexiform neurofibroma and used off-label for the associated glioma. ^[6]
• NTRK fusions: larotrectinib or entrectinib can produce rapid, durable responses. ^[6]

Gross total resection is the single most important treatment step in ependymoma, and most children with incomplete resection will progress. After surgery, focal radiotherapy to the tumour bed and residual disease is standard even in young children, because withholding radiotherapy leads to a much higher relapse rate. Modern paediatric series use a median dose of about 54 Gy with photons and 59.4 Gy with protons. ^[9] Chemotherapy (often vincristine, cisplatin or carboplatin, and cyclophosphamide or ifosfamide) is used before or between surgeries for infants under one to three years in whom radiotherapy is being deferred, for subtotally resected disease and at relapse, but it is less effective as a primary treatment than surgery and radiotherapy. ^[7][9]

Key ependymoma points:

• Posterior fossa ependymomas of the PF-A molecular group, which are seen in young children, have a worse prognosis than the PF-B group more commonly seen in older children and adults.
• Second-look surgery after a partial resection is often worthwhile, because a tumour that was too close to the brainstem to remove safely may become resectable once some of it has shrunk.
• Leptomeningeal dissemination is uncommon at presentation but should be ruled out with craniospinal imaging.
• Recurrence is often local and can sometimes be treated with further surgery followed by re-irradiation.

These are best understood as two different entities that share an address:

• Focal brainstem gliomas, usually low-grade (often pilocytic), grow out of the brainstem surface or the cerebellar peduncle. They can often be resected at least partially, and their prognosis resembles that of other low-grade gliomas.
• Diffuse midline glioma, the lesion formerly called diffuse intrinsic pontine glioma (DIPG), is centred in the pons, infiltrates the brainstem and bridges crossing tracts. It is not amenable to surgical removal. Fractionated focal radiotherapy is the only treatment with a consistent, though temporary, effect: it relieves symptoms and delays progression by a few months, without a lasting survival benefit. Chemotherapy and most targeted drugs have not improved outcome. ^[8]

Because a treatable tumour (an ependymoma, a pilocytic astrocytoma, a germinoma or an inflammatory lesion) can occasionally mimic a pontine glioma, a stereotactic biopsy is increasingly performed to confirm the diagnosis and to obtain tissue for molecular studies, including H3 K27M immunohistochemistry and sequencing. ^[8] Treatment in many countries is offered within clinical trials, because none of the available options is curative. Families should be told early that the goal of treatment is to maximise quality of time rather than to cure.

Hydrocephalus is managed with a ventricular shunt or third ventriculostomy, and corticosteroids may briefly reduce peritumoural oedema. The child needs anticipatory planning for swallowing, communication and airway support as the disease advances.

Intracranial germ cell tumours (iGCT) are a distinct, highly treatable group clustered in the pineal and suprasellar regions, with peak incidence in early adolescence. ^[4]

Germinoma is exquisitely sensitive to both radiotherapy and chemotherapy. Two approaches are in use, and both are effective:

• Radiotherapy alone: whole ventricular radiotherapy at 21 to 24 Gy with a tumour boost to a total of 40 to 45 Gy. ^[4]
• Neoadjuvant chemotherapy followed by response-adapted radiotherapy, which is preferred by international guidelines for neurocognitive and endocrine sparing. Patients receive four cycles of carboplatin and etoposide ("carboPEI") followed by 24 Gy whole ventricular radiotherapy in those in complete remission, with the classical 16 Gy tumour boost given only if residual disease is present. In the SIOP-CNS-GCT II trial, the 166 patients with localised germinoma treated this way had a five-year event-free survival of 94 percent and an overall survival of 98 percent; 39 percent were in complete remission after chemotherapy and could safely omit the boost. ^[5]

Disseminated germinoma receives craniospinal radiotherapy at 24 Gy with a 16 Gy boost to all sites; some regimens add neoadjuvant chemotherapy and reduce the craniospinal dose to 21 Gy. ^[4][5]

Teratomas, choriocarcinomas, yolk sac tumours, embryonal carcinomas and mixed tumours require multimodal therapy, because radiotherapy alone gives poor control. Four to six cycles of multiagent chemotherapy containing a platinum drug and etoposide (with or without cyclophosphamide or ifosfamide), followed by second-look surgery and craniospinal radiotherapy (30 to 36 Gy) with a tumour boost to a total of 54 to 60 Gy, gives a five-year overall survival of 98 percent for those treated on the COG ACNS0122 protocol. ^[4] Mature teratoma is managed surgically if completely resected, with focal radiotherapy for residual disease. ^[4]

NGGCTs are divided into three prognostic groups. A good-prognosis group contains pure germinoma and beta-hCG-secreting germinoma with syncytiotrophoblasts; an intermediate group contains immature teratoma and germinoma with a teratomatous component; and a poor-prognosis group contains choriocarcinoma, yolk sac tumour, embryonal carcinoma, mixed tumours with these components, and tumours with serum beta-hCG of 2000 IU per L or more, or AFP of 2000 ng per mL or more. ^[4]

Survival has become the expected outcome for most children, which makes the long-term cost of treatment a central part of the disease. Late effects are predictable, cumulative and, for some, preventable. ^[7]

• Neurocognitive effects. Intelligence, processing speed, attention, memory and executive function are most affected by whole-brain and craniospinal irradiation, especially in children treated before the age of seven years. Cerebellar surgery can additionally produce cerebellar mutism, dysarthria and ataxia. Planning treatment around proton therapy and modulated radiation techniques, hippocampal avoidance, and limiting whole-brain volumes all reduce the cognitive load. ^[7][9]
• Endocrine dysfunction. Growth hormone deficiency is the commonest endocrine late effect after cranial irradiation, followed by thyroid dysfunction after craniospinal fields and, at high doses, gonadotrophin and cortisol failure. Diabetes insipidus persists from a suprasellar tumour. Growth velocity and thyroid function should be checked at every visit. ^[7]
• Hearing loss. Cisplatin and cranial radiation both damage the cochlea. High-frequency hearing loss is frequent and permanent in medulloblastoma survivors. Sodium thiosulfate, given with cisplatin, reduces hearing loss by roughly 50 percent and is licensed in children, adolescents and young adults with non-metastatic tumours; amifostine is not recommended because it has not shown efficacy in pooled analyses. ^[7]
• Second neoplasms. Alkylating agents, epipodophyllotoxins and radiation are associated with later leukaemia, meningioma and high-grade glioma. Meningiomas appear particularly after high doses of cranial radiation, decades after treatment.
• Cerebrovascular disease. Survivors of cranial irradiation are at increased risk of stroke and moyamoya disease, and should have blood pressure and neurological function reviewed regularly.
• Fertility and pubertal effects. Alkylating chemotherapy and pelvic radiation for spinal fields can impair gonadal function; sperm banking and oocyte preservation should be offered before treatment where feasible, and the discussion should be age-appropriate and sensitive.
• Vasoplegia and posterior fossa syndrome, fatigue, and psychosocial difficulties (anxiety, depression, social isolation, impaired educational attainment) are under-recognised.

• A contrast-enhanced CT, where MRI is unavailable, can diagnose most paediatric brain tumours in the hands of a trained radiologist, and it is the pragmatic first step in many regions.
• Basic shunting supplies and access to neurosurgical expertise, even through referral networks, prevent deaths from hydrocephalus.
• Chemotherapy regimens such as carboplatin and vincristine use generic drugs that are widely available, although the infrastructure for safe central line care, blood product support and infection control must accompany them.
• Tumour marker measurement in both serum and CSF is low-cost and decisively changes the management of pineal and suprasellar lesions.
• Proton therapy and molecular testing are concentrated in high-income centres. Planning should therefore aim to deliver the high-cure components (surgery, older standard chemotherapy and conventional radiotherapy) reliably, while arranging referral pathways for children who are likely to benefit from proton therapy or targeted agents.
• Surveillance for survivors is possible with clinical examination, thyroid and growth assessment and psychological support, even without advanced imaging at every visit.

• Primary brain tumours are the commonest solid tumours of childhood and the leading cause of cancer death in children; more than 4,000 are diagnosed annually in children and teenagers in the USA alone. ^[1][2]
• Most childhood tumours are in the posterior fossa or along midline; raised intracranial pressure is the common presenting mode, with morning headache, vomiting and gait unsteadiness.
• Medulloblastoma, pilocytic astrocytoma and ependymoma are the three posterior fossa tumours to recognise: medulloblastoma is a malignant midline vermian mass; pilocytic astrocytoma is cystic, low-grade and often curable surgically; posterior fossa ependymoma moulds the fourth ventricle.
• Medulloblastoma is now classified into WNT, SHH, group 3 and group 4; prognosis runs from above 90 percent five-year survival in WNT to about 40 percent in group 3. ^[1]
• Infants under three years with medulloblastoma need chemotherapy-first strategies to defer or avoid craniospinal irradiation.
• Pilocytic and other low-grade gliomas are the commonest paediatric CNS tumours; carboplatin and vincristine or vinblastine is the standard chemotherapy, with five-year progression-free survival of 40 to 50 percent; BRAF, MEK, FGFR and NTRK targeted drugs are now part of care. ^[6]
• Ependymoma is best treated by gross total removal followed by focal radiotherapy at about 54 Gy photons or 59.4 Gy protons. ^[9]
• Diffuse midline glioma is a disease of children aged 5 to 10 with a median survival under one year; radiotherapy palliates, but no treatment is curative. ^[8]
• Germinoma is treated with whole ventricular radiotherapy of 24 Gy, with a 16 Gy tumour boost only if residual disease remains after chemotherapy; SIOP-CNS-GCT II showed 94 percent event-free survival and 98 percent overall survival. ^[5]
• Non-germinomatous germ cell tumours need platinum and etoposide-based chemotherapy, second-look surgery and craniospinal radiotherapy of 30 to 36 Gy plus a tumour boost to 54 to 60 Gy. ^[4]
• Tumour markers (AFP and beta-hCG in serum and CSF) are central to the diagnosis of germ cell tumours; thresholds differ between cooperative groups. ^[4]
• Craniospinal imaging and CSF cytology stage medulloblastoma and germ cell tumours; bifocal pineal and suprasellar disease is treated as non-disseminated germinoma. ^[1][4]
• Late effects - neurocognitive injury, endocrine failure, hearing loss, second tumours and cerebrovascular disease - dominate modern survivorship and must be anticipated from diagnosis. ^[7]
• Sodium thiosulfate reduces cisplatin-induced hearing loss by about half and is an important standard treatment in children with non-metastatic medulloblastoma or germ cell tumours. ^[7]
• Every child should be managed by a paediatric neuro-oncology multidisciplinary team and, where possible, on or alongside SIOP or COG protocols; NICE NG99 describes a similar multidisciplinary standard for adults. ^[3][4][5]

Atrial myxoma (cardiac tumours), Li-Fraumeni syndrome, neurofibromatosis type 1, tuberous sclerosis, growth hormone deficiency, diabetes insipidus, syndrome of inappropriate antidiuretic hormone secretion, precocious puberty, paediatric oncology, radiotherapy-related late effects, school reintegration after chronic illness.