Revamping CNS Tumor Reporting for Accuracy

Authors

• Corey Neff, Central Brain Tumor Registry of the United States
• Quinn T. Ostrom, Central Brain Tumor Registry of the United States
• Carol Kruchko, Central Brain Tumor Registry of the United States

Documenting brain and other central nervous system tumors requires certain nuances to remain accurate.

Brain and other central nervous system (CNS) tumors are a diverse collection of tumors comprising over 100 unique International Classification for Diseases, Oncology, 3rd edition (ICD-O-3) histopathology codes, yet they are often reported in local and national cancer statistics as a single category. Moreover, among brain and other CNS tumors, nonmalignant neoplasms are rarely included in overall statistics describing the epidemiology of tumors of the brain and other CNS despite being more common and their collection being mandated since diagnosis year 2004.¹

In order to provide an accurate and comprehensive account of the burden of these tumors, the use of a clinically relevant histopathology grouping scheme is necessary. Starting in June 2023, a grouping developed by The Central Brain Tumor Registry of the United States (CBTRUS) will be available in NAACCR Cancer in North America (CiNA) datasets.

The Central Brain Tumor Registry of the United States

CBTRUS was founded in 1992 to address this limitation.² The CBTRUS aggregates incident cancer cases from the Centers for Disease Control and Prevention’s (CDC) National Program of Cancer Registries (NPCR) program and the National Cancer Institute’s (NCI) Surveillance, Epidemiology and End Results (SEER) program yearly for use in annual reports and publications.³

Since its inception, the CBTRUS has regularly collaborated with neuropathologists to develop and maintain a clinically relevant histopathology grouping that accounts for the numerous unique histopathology codes used in the diagnosis of brain and other CNS tumors. This tumor grouping scheme, most recently updated in 2021 to align with the 2016 WHO Classification of Tumors of the CNS, groups all brain and other CNS tumors into 31 distinct histopathology groups irrespective of tumor behavior.⁴

There are several notable differences in the definition of brain and other CNS tumors between different reporting groups, which should be noted when using site-specific recodes. SEER, NAACCR, and NPCR define brain and other CNS tumors as tumors located in the brain, meninges, and other central nervous system tumors (ICD-O-3 site codes: C70.0-9, C71.0-9, and C72.0-9), with the exclusion of lymphoma and leukemia histopathologies (ICD-O-3 codes 9590-9989) occurring at those sites.

CBTRUS includes the brain, meninges, other central nervous system tumors, pituitary, craniopharyngeal duct, and pineal gland (ICD-O-3 site codes: C70.0-9, C71.0-9, C72.0-9, C73.3-5), as well as olfactory tumors of the nasal cavity (ICD-O-3 site code: C30.0, ICD-O-3 histopathology codes 9522-9523 only) and lymphomas and leukemias occurring at brain and CNS sites.

Defining Different Tumors

The inclusion of tumors of the pituitary, craniopharyngeal duct, pineal gland, and primary central nervous system lymphoma as CNS tumors align with the WHO classification of central nervous system tumors, but their inclusion in a site-specific recode is unique to the CBTRUS grouping scheme. CBTRUS also includes all primary brain and other CNS tumors, irrespective of behavior. Brain tumors with ICD-O-3 behavior codes /0 (benign) and /1 (borderline) are referred to as non-malignant brain tumors. Many reports using the term “brain tumor” or “brain cancer” may be restricted to malignant brain tumors only, despite these tumors representing only ~30% of primary brain tumors.³

To facilitate broader use of clinically relevant histopathology groupings for tumors of the brain and CNS by the cancer registry community, CBTRUS has worked with NAACCR to provide the CBTRUS histopathology recode within NAACCR Cancer in North America (CiNA) datasets, including CiNA Public Use Data. The CBTRUS grouping was evaluated against the existing SEER brain and other CNS grouping using the CiNA dataset. The results of this initial evaluation were promising, motivating NAACCR to include this recode in all further releases of the CiNA dataset beginning June 2023.⁵

Analyzing the Details

As incidence, survival, and clinical features all vary significantly by histopathology for tumors of the brain and other CNS, the CBTRUS grouping delivers a more robust, clinically-driven representation of the burden of brain and other CNS tumors. We encourage the use of the CBTRUS variable not only for neuro-oncology research but across the whole cancer registry community for the production of more detailed, comprehensive, and clinically relevant cancer statistics.

A detailed description of the comparison between the CBTRUS and SEER brain and other CNS groupings can be found in the article by Ostrom et al., “The Central Brain Tumor Registry of the United States Histopathological Grouping Scheme Provides Clinically Relevant Brain and other Central Nervous System Categories for Cancer Registry Data,” published in the 2023 Winter NAACCR Special Edition of the Journal of Registry Management.

References

1. Benign Brain Tumor Cancer Registries Amendment Act, 107th Cong. § 260 (2002). http://www.gpo.gov/fdsys/pkg/PLAW-107publ260/pdf/PLAW-107publ260.pdf. Accessed July 21, 2020.
2. Kruchko C, Ostrom QT, Gittleman H, Barnholtz-Sloan JS. The CBTRUS story: providing accurate population-based statistics on brain and other central nervous system tumors for everyone. Neuro Oncol. 2018; 20(3):295-298.
3. Ostrom QT, Price M, Neff C, et al. CBTRUS Statistical Report: Primary Brain and Other Central Nervous System Tumors Diagnosed in the United States in 2015-2019. Neuro Oncol. 2022; 24(Suppl 5):v1-v95.
4. Waite KA, Cioffi G, Kruchko C, et al. Aligning the Central Brain Tumor Registry of the United States (CBTRUS) histology groupings with current definitions. Neurooncol. Pract. 2022; 9(4):317-327.
5. Ostrom Q, Kruchko C, Neff C, Firth A, Sherman R. The Central Brain Tumor Registry of the United States Histopathological Grouping Scheme Provides Clinically Relevant Brain and other Central Nervous System Categories for Cancer Registry Data. J. Registry. Manag. 2023.