SITE SPECIFIC DATA ITEMS (SSDI)/ GRADE

Multiple brain molecular markers have become standard pathology components necessary for diagnosis. This data item captures clinically important brain cancer subtypes identified by molecular markers that are not distinguishable by ICD-O-3 codes.

Collection of these clinically important brain cancer subtypes has been recommended by CBTRUS.

**Definition** If a mutation or alteration is in the name of the histopathology, it is required for diagnosis as it helps distinguish among clinically important subtypes within ICD-O-3.  * _IDH mutation status_ distinguishes between clinically important subtypes within ICD-O-3 9400/3, Diffuse astrocytoma and 9401/3, Anaplastic astrocytoma. * _IDH mutant and 1p/19q co-deletion_ distinguishes between clinically important subtypes within ICD-O-3 code 9450/3, Oligodendroglioma and 9451/3, Anaplastic Oligodendroglioma. * _IDH-wildtype_ distinguishes clinically important subtypes within ICD-O-3 9400/3, Diffuse astrocytoma, 9401/3, Anaplastic astrocytoma and 9440/3, Glioblastoma, Epithelioid glioblastoma and Glioblastoma, NOS (note that the new ICD-O-3 code 9445/3 applies to Glioblastoma, IDH-mutant; information regarding this subtype is not collected using this data item). * _SHH-activation and TP53-wildtype_ distinguishes between clinically important subtypes within ICD-O-3 histology code 9471/3, Medulloblastoma. * _C19MC alteration_ status distinguishes a clinically important highly aggressive subtype within ICD-O-3 9478/3, Embryonal tumor with multilayered rosettes. * _Pediatric-type diffuse low-grade gliomas_: 9385/3 Diffuse hemispheric glioma, H3-G34-mutant, Diffuse midline glioma, H3 K27-altered, Diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype, and Infant-type hemispheric glioma. * _Ependymal tumors_ are distinguished by mutations required for diagnosis among clinically important subtypes: 9396/3 Posterior fossa group A (PFA) ependymoma, Posterior fossa group B (PFB) ependymoma, Spinal ependymoma, \_MYCN\_-amplified, Supratentorial ependymoma, _YAPI_ fusion-positive, and Supratentorial ependymoma, _ZFTA_ fusion-positive. * _Pediatric-type diffuse low-grade gliomas_ are distinguished among subtypes by mutations required for diagnosis: 9421/1 Diffuse astrocytoma, \_MYB\_-or \_MYBL1\_-altered, Diffuse low-grade glioma, MAPK pathway-altered, and Pilocytic astrocytoma. * _Circumscribed astrocytic tumors_ are distinguished among subtypes by mutations required for diagnosis: 9430/3 Astroblastoma, MN1-altered and Astroblastoma. * _Other CNS embryonal tumors_ are distinguished among subtypes by mutations required for diagnosis: 9500/3 CNS neuroblastoma\_, FOXR2\_-activated, CNS tumor with _BCOR_ internal tandem duplication, and Neuroblastoma, NOS.

Each Site-Specific Data Item (SSDI) applies only to selected primary sites, histologies, and years of diagnosis. Depending on applicability and standard-setter requirements, SSDIs may be left blank.