Low-grade gliomas

Low-grade gliomas are the most common brain tumour in the paediatric age group. Most paediatric low-grade gliomas are pilocytic (grade 1). In this category, cerebellar astrocytomas are the prototype of the so-called surgical tumours and complete resection is curative. When resection is incomplete, a wait and watch approach is recommended and repeat surgery is only performed in case of progression of residual tumour [39].

When the tumour is located in an unresectable location such as the optic pathway or the brainstem (although a subset of these tumour are amenable to complete or subtotal resection), non-surgical treatment may be considered, based on the risk associated with tumour progression. Chemotherapy is the treatment of choice, with several potential options [37]. The combination of vincristine and carboplatin is a standard regimen worldwide [40]; however, other protocols have shown benefit (such as TPCV—a combination of thioguanine, procarbazine, lomustine and vincristine [41]—the etoposide-cisplatin [42] combination, or single agent vinblastine [43] or vinorelbine [44] amongst others). The response rate to chemotherapy varies from 30 to 70 %. However, most children will eventually show progression and will require further treatment. Recent reports have suggested that multiple lines of chemotherapy allow avoidance of radiation [45]. Still, the management of children with unresectable low-grade gliomas is challenging and the respective role of chemotherapy and focal radiation is currently unsettled, particularly in children who show progression after a first line of chemotherapy.

Medulloblastoma

Most common malignant brain tumour in the paediatric age group, medulloblastoma is often not diagnosed in countries with limited resources, as children essentially succumb before diagnosis. When the tumour is identified on imaging, treatment should ideally include surgery followed by craniospinal radiation and chemotherapy, depending of the resources available. Ideally patients should have a complete preoperative staging prior to surgery, including MRI scan of the brain and the spine. If this radiological assessment does not show evidence of dissemination, maximum resection should be attempted, as extent of resection has a significant impact on survival [22]. In children with disseminated disease, the impact of resection is less obvious. Radiation should include the craniospinal axis with a boost to the posterior fossa or the tumour bed. The dose to the posterior fossa depends on the initial staging: children with no evidence of dissemination (no evidence of metastatic disease on initial imaging, and no evidence of CSF involvement on CSF cytology performed at least 10 days after surgical resection), the recommendation is a dose f 23.4 Gy to the craniospinal axis in 13 fractions and a posterior fossa or (better) a tumour bed boost of 30.6 Gy is recommended [29]. For patients with incomplete resection (residue >1.5 cm in diameter) or patients with metastatic disease, a dose of 36 Gy in 20 fractions with a boost of 18 Gy to the posterior fossa/tumour bed is recommended [46]. Numerous chemotherapy protocols could be used. The current template used by the SIOP committee is a combination of etoposide and cisplatin for three courses, followed by a combination of cyclophospamide and vincristine for three courses.

Ependymoma

Ependymoma accounts for around 10 % of paediatric CNS tumours. More than 90 % occur in the brain; two thirds of them in the posterior fossa [23]. Clinical presentation depends on the site of the tumour.

The histological grading of ependymoma and its correlation with outcome is still a matter of controversies. So far, the treatment of ependymoma is essentially identical, regardless of the histological grading (i.e. grade 2 or grade 3). The most widely accepted prognostic factor is the degree of surgical resection with complete resection associated with a better prognosis (70–80 % overall survival) at 5 years with gross total resection compared to 30 % with subtotal/partial resection [38]. Therefore the role of the surgeons is critical and second look surgery is recommended in case of incomplete resection. The role of chemotherapy is still unclear in this disease [47]. There is some suggestion that chemotherapy may facilitate a second resection when residual tumour is present after initial resection. In any case, radiation is a critical component of the post-operative treatment. Modern techniques of radiation allow the delivery of high dose radiation in small volumes without significant impact on neurocognitive outcome. In this context, current protocols in high-income countries consider focal radiation at a dose of 54–59.4 Gy in 1.8 G fractions since the age of 1 [30]. When conformal or stereotactic radiation is not available, chemotherapy may be an alternative in infants and young children under the age of 3 [48, 49]. However, the results of a post-operative chemotherapy-only approach are essentially disappointing.