ESTRO 36 Abstract Book

S208

ESTRO 36 2017

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importance of this molecular biomarker is reflected in the

updated WHO classification of central nervous system

tumours that was published in 2016.

Long term data from two large, randomised trials have

shown that patients with 1p19q co-deleted anaplastic

oligodendrogliomas derive significant survival benefit

from the addition of chemotherapy to radiotherapy. More

recent data from the NOA-04 study indicate that primary

chemotherapy is not superior to primary radiotherapy in

any molecular subgroup of anaplastic glioma and hence do

not support the concept of ‘delayed radiotherapy’ in these

patients.

Despite the documented association of chemosensitivity

with 1p19q co-deletion, a recent planned interim analysis

of the CATNON study revealed that patients with

anaplastic astrocytomas with inatct 1p19q chromosomal

regions also derive significant benefit from the addition of

adjuvant temozolomide to radiotherapy. It is not yet

known whether the use of temozolomide concomitant

with radiotherapy confers additional benefit; these hotly

anticipated data are not expected to be available for at

least two years.

Hence, all patients with grade III gliomas appear to benefit

from both chemotherapy and radiotherapy, with maximum

survival benefit being achieved by ‘early’ rather than

‘delayed’ treatment. A number of questions remain,

including the optimum scheduling of these treatments and

the optimum radiotherapy regime for the different

molecular subtypes. The question of radiation dose and

volume is particularly important for this group of patients

in whom long term survival can be anticipated and the

risks and potential impact of neurotoxicity are significant.

Strategies to reduce the long term neurocognitive impact

of radiotherapy in these patients should be developed and

incorporated into future clinical trials.

SP-0392 ‘Paediatric’ brain tumours in adults

C. Seidel

Universitätsklinikum Leipzig, Klinik für Radioonkologie

und Strahlentherapie, Leipzig, Germany

Paediatric brain tumours are rare in adults. Prospective

trials are often lacking and treatment recommendations

are essentially based on the experiences in children –

although tumors in adults are different in many aspects.

Efficacy and applicability of “paediatric” approaches in

adult patients is therefore a matter of debate.

Medulloblastoma (MB): MB is the most common brain

tumor in children. It is relatively rare in adults, with an

estimated incidence of 0.6 per million. MB in adults differ

from the paediatric population in terms of location of

tumor, histologic and molecular subtype and course of

disease. In children MB frequently arise in the midline at

the floor of the 4

ventricle and vermis, whereas in adults

the hemispheres are primarily involved. In children the

majority of histological subtypes consist of the classical

variant. In adults the desmoplastic variant is more

frequently found. In adults late relapses are frequent. Like

in children, surgery followed by radiotherapy is the

standard of care. The addition of adjuvant chemotherapy

confers a survival benefit according to a large

retrospective analysis of American National database in

more than 400 adult patients. After adjustment for

relevant demographic and clinical factors, this study

found that the addition of adjuvant chemotherapy to

craniospinal irradiation was associated with superior

overall survival for adult MB. In the recently closed

German NOA-7 trial the addition of maintenance

chemotherapy with 8 cycles cisplatin, vincristine and

CCNU was investigated in a prospective, multicentric

setting. Toxicity and survival profile of this study will be

important for future treatment protocols. Novel

stratifications of treatments in childhood MB are

increasingly based on molecular genetic profiles. There

have been clues over the past decade that adult MB is

biologically separate from childhood medulloblastoma. It

has been shown that adult MB comprises 3 molecular

variants rather than 4 and that the majority of tumors are

SHH with smaller percentages comprising Wingless (WNT)

and group 4. Moreover, several genomic studies have

suggested that adult SHH MB is distinct from the pediatric

entity, being enriched for PTCH1 and SMO mutations and

coupled with a near absence of TP53 mutations. It can be

expected that these information will in future gain an

increasing importance for selecting adequately tailored

treatment concepts for adult MB. Ependymoma (EP): Adult

intracranial ependymoma are rare accounting for 2% to 5%

of all intracranial malignancies. Decisive management

principles were established accross the age groups,

especially the attempt for radical resection. Postoperative

local radiotherapy is the standard of care in children

regardless of histological subtype. The role of adjuvant

radiotherapy in the adult, however, is unclear and subject

to controversies. The role of additional chemotherapy is

unclear in children and adults. In children genetically

distinct subgroups have been identified by genomic

alteration in classic grade II and III ependymomas. They

are supratentorial ependymomas with C11orf95-RELA

fusion or YAP1 fusion, infratentorial ependymomas with

high (type B) or low (type A) copy alteration number, and

spinal cord ependymomas. Myxopapillary ependymomas

and subependymomas have different biology and a better

prognosis than ependymomas with typical WHO grade II or

III histology. However, data for adults is scarce.

Translation of molecular findings into clinical practice and

adapted treatments is essential both for children and

adults with the aim to improve tumour control and

survival. Embryonal tumours (former stPNET): According

to the new WHO classification of 2016 the former stPNET

are now classified as embryonal tumours with distinct sub-

classifications according to conventional histological

description and the availability of molecular genetic

profiles. Until today treatment concepts are still based on

the traditional histological description both in children

and adults. Embryonal tumours at supratentorial location

are rare. Treatment concepts for these tumours both for

children and adults are controversial. Surgery and

craniospinal irradiation are still the corner stones in

treatment management for both children and adults. The

addition of chemotherapy is subject to prospective trials

in children. With the introduction of the new classification

and molecular genetic profiles adapted treatment

concepts will evolve in future both for children and

adults. Key points: Current concepts for paediatric CNS

tumours in adults are based on experiences generated in

paediatric neuro oncology. It is an open question whether

these concepts prove to be as efficient and feasible. Late

effects are known in children, but information is scarce

for adults. There is a need for specifically tailored

concepts in adults.

Symposium: MR guided radiotherapy: the new standard

of care in 10 years time

SP-0393 Clinical opportunities with MR guided

external beam RT

S. Mook

UMC Utrecht, Department of Radiation Oncology,

Utrecht, The Netherlands

Nowadays, image guided radiotherapy is considered

standard of care and is an integrated part of radiation

treatment. Currently, cone beam computer tomography is

the modality of choice for image guidance, however,

limited soft tissue contrast and the absence of real time

intrafraction imaging cause restrictions to its application.

The superior soft tissue visualization of MRI was the

incentive for the development of the MR linac system,