Rare Embryonal Tumors of the Central Nervous System: International Registry

CNS tumors are the most common solid malignancies and the leading cause of children's cancer-related mortality. Embryonal tumors account for approximately 20-25% of all primary CNS tumors in children. Although medulloblastomas are the most commonly diagnosed malignant brain tumors, other embryonal tumors are relatively rare. Several studies of rare embryonal tumors have been published, but the number of included patients is generally small. Diagnosis of different subtypes of rare embryonal tumors can be extremely challenging. Because of limited data, there are no standard treatment recommendations for patients with rare embryonal tumors.

Embryonal tumors with multilayered rosettes (ETMR), FOXR2-activated CNS neuroblastoma, cribriform neuroepithelial tumor, CNS tumor with BCOR internal tandem duplication, and embryonal tumors not otherwise specified/not elsewhere classified (NOS/NEC) are extremely rare. Moreover, FOXR2-activated CNS neuroblastoma, cribriform neuroepithelial tumor, and CNS tumor with BCOR internal tandem duplication were first described in the fifth edition of the WHO Classification of Tumors of the Central Nervous System, published in 2021. Because of the rarity of these tumors, randomized controlled clinical trials are extremely complicated to conduct. Considering the lack of studies from low- and middle-income countries (LMICs) it is not excluded that cases of rare embryonal tumors are more common than have been described in the literature. Hence, evidence can be generated through registry studies.

This is a multicenter international retrospective and prospective registry to collect and analyze data from pediatric and young adult patients diagnosed with rare CNS embryonal tumors. Patients will be recruited directly by participating centers and national study groups. Participating centers will collect and verify the informed consent of all prospective patients enrolled at their centers.

Patients diagnosed with rare embryonal tumors of the CNS (ETMR, FOXR2-activated CNS neuroblastoma, cribriform neuroepithelial tumor, CNS tumor with BCOR internal tandem duplication, embryonal tumors NOS/NEC) since 01.01.2010 will be included. ETMR has been included in the WHO classification of CNS tumors since 2016 and encompasses three morphologically distinct embryonal tumors (Embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma (EBL) and medulloepithelioma (MEPL)) that were previously classified as CNS primitive neuroectodermal tumors (CNS-PNETs). These histological subtypes should also be included in the study. Considering the lack of molecular genetic tests done among retrospective cases, the investigators will also include all patients diagnosed with neuroblastoma and ganglioneuroblastoma.

The following data will be collected through questionnaires:

1. Patient characteristics

2. Characteristics of rare CNS embryonal tumors

3. Details of the diagnosis and treatment

4. Complications and late effects of treatment

5. Outcomes

6. Follow-up information

Quality control and data management will be conducted by the Immune Oncology Research Institute.