Tumours of central nervous system (CNS) is the most common type of solid tumour in childhood. In China, there is limited epidemiology information. Released data from Chinese CDC did not include types of CNS tumours and geographic contribution. As the Children's Neuro-Oncology Group (CNOG) was established in China in May 2017, it makes studies from multiple centers in children's brain tumors become practical. This retrospective cross-sectional study was aligned on CNOG annual meeting in 2018 and research group was named as CNOG-MC001 (MC, multicenter) collaborative group.

CNS tumours are mostly seen solid tumours in childhood , as the second common malignancy following leukemia in children. The annual age-standardized incidence rate per 1,000,000 person-years (ASR) of CNS tumour in international children's cancer incidence study is 20-30. In Asia, ASR of paediatric CNS tumours is around 15.0-24.9 in Japan, Korea, Singapore. For Chinese races including mainland of China, Taiwan and Hong Kong, ASRs of paediatric CNS tumour are 15.0, 17.4 and 23.8.

In 2017 in Shanghai, Children's Neuro-Oncology Group (CNOG) was found in 5th CSPN (Chinese Society of Pediatric Neurosurgery) / 9th CPNF (China Pediatric Neurosurgery Forum) conference, with 35 founding member institutions and 30 founding observation member institutions in mainland of China. Based on this progress, national wide registry (CNOG-MC001) was settled to obtain basic information about CNS tumour cases, combined with available epidemiology data from publications to assess current medical situation on paediatric CNS tumours in China. The protocol of CNOG-MC001 was aligned by CSPN and CNOG member institutions in CNOG annual meeting in 2018 and the study ofiicially started right after the meeting on 20181027.

The first step of this study is a national wide pre-survey to all 35 CNOG member institutions and other 22 CSPN members. The pre-survey data sheet included number of annual surgically treated paediatric CNS tumour cases (age ranging from 0 to 18 years old, classified by WHO Classification of Tumours of the Central Nervous System 2016 version), to assess the proper sites to be involved in this study. After retrieving the pre-survey results, large-scale, detailed case data sheets will be sent to participating institutions as members of CNOG-MC001 collaborative group.

Inclusion Criteria:

• patients who were newly diagnosed with CNS tumour admitted for in-patient treatments during period of Jan.1st 2016 to Dec. 31st 2017

• patients who were less than 18 year-old at diagnosis

• patients with available mandatory information as age, gender during enrollment

• patients must have pathological diagnosis of tumours, which followed 2016 edition of the World Health Organization (WHO) Classification of Tumours of the Central Nervous System (CNS), except the following conditions:

  1. Diffuse Intrinsic Pontine Glioma (DIPG) according to classic symptoms and typical MRI
  2. confirmed NF1 patients with classic symtoms and MRI representing Optic Pathway Glioma (OPG) with no surgical treatment indications will be marked as "pilocytic astrocytoma"
  3. patients with newly diagnosed recurrence or metastasis of previously confirmed (before Jan.1st 2016) Embryonal Tumours (medulloblastoma, emryonal tumour with multilayered rosettes - C19MC altered, atypical teratoid / rhabdoid tumour / others) and high grade gliomas (glioblastoma, anaplastic astrocytoma) that were unwilling to recieve second surgical treatment / inoperable / without surgical indication, will be marked as original diagnosis
  4. patients with newly diagnosed relapse of previously confirmed (before Jan.1st 2016) low grade glioma (defined as pilocytic astrocytoma, diffuse astrocytoma, pilomyxoid astrocytoma, pleomorphic xanthoastrocytoma, subependymal giant cell astrocytoma, oligodendroglioma, oligoastrocytoma, ganglioglioma, desmoplastic infantile astrocytoma and ganglioglioma, dysembryoplastic neuroepithelial tumour, papillary glioneuronal tumour, rosette-forming glioneuronal tumour of the fourth ventricle, angiocentric glioma, dysplastic cerebellar gangliocytoma, extraventricular neurocytoma, cerebellar liponeurocytoma, and central neurocytoma) and ependymal tumours in cross-sectional period, who were unwilling to be operated / inoperable / without surgical indication, will be marked as original diagnosis

• clinical, image and pathology data of patients with unidentified pathological diagnosis from member sites of CNOG-MC001 collaborative group will be sent to study center for reviewing; cases with unidentifiable diagnosis after center review and alignment with CNOG-MC001 sites will be marked as "unknown"

Exclusion Criteria:

• confirmed CNS metatasis patients whose tumour tissues were obtained from other systems other than CNS will be excluded
• patients with newly diagnosed recurrence or metastasis of previously confirmed CNS Tumours, will be excluded when primary tumour diagnosis and progression time points were both in cross-sectional period; these patients will be only enrolled as "newly diagnosed cases with primary tumours" and recorded as "progressed in follow-up" in follow-up data sheet
• patients with newly diagnosed relapse of previously confirmed (before Jan.1st 2016) low grade glioma and ependymal tumours, who were unwilling to be operated / inoperable, and were suspected as malignant transformation, will be excluded due to lack of pathological diagnosis
• patients with insufficient or inconsistant data (e.g: patient diagnosed with primary medulloblastoma with tumour located in cerebral) will be excluded in center review after consulting with data-upload institutions

Newly diagnosed paediatric (0-18 y/o) CNS tumous in period of Jan.1st 2016 to Dec.31st 2017, with sufficient baseline data and clear pathological diagnosis according to classification of CNS tumours - WHO 2016 version (for exceptions please refer to eligibility criteria)