Context.—

Integration of molecular data into glioma classification supports diagnostic, prognostic, and therapeutic decision-making; however, testing practices for these informative biomarkers in clinical laboratories remain unclear.

Objective.—

To examine the prevalence of molecular testing for clinically relevant biomarkers in adult and pediatric gliomas through review of a College of American Pathologists proficiency testing survey prior to the release of the 2021 World Health Organization Classification of Central Nervous System Tumors.

Design.—

College of American Pathologists proficiency testing 2020 survey results from 96 laboratories performing molecular testing for diffuse gliomas were used to determine the use of testing for molecular biomarkers in gliomas.

Results.—

The data provide perspective into the testing practices for diffuse gliomas from a broad group of clinical laboratories in 2020. More than 98% of participating laboratories perform testing for glioma biomarkers recognized as diagnostic for specific subtypes, including IDH. More than 60% of laboratories also use molecular markers to differentiate between astrocytic and oligodendroglial lineage tumors, with some laboratories providing more comprehensive analyses, including prognostic biomarkers, such as CDKN2A/B homozygous deletions. Almost all laboratories test for MGMT promoter methylation to identify patients with an increased likelihood of responding to temozolomide.

Conclusions.—

These findings highlight the state of molecular testing in 2020 for the diagnosis and classification of diffuse gliomas at large academic medical centers. The findings show that comprehensive molecular testing is not universal across clinical laboratories and highlight the gaps between laboratory practices in 2020 and the recommendations in the 2021 World Health Organization Classification of Central Nervous System Tumors.

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Author notes

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All authors except Brat are current or past members of the College of American Pathologists Molecular Oncology Committee. Fernandes is the American Association for Clinical Chemistry liaison to the College of American Pathologists Molecular Oncology Committee. Souers and Vasalos are employees of the College of American Pathologists. Ramkissoon receives salary and stock equity from Laboratory Corporation of America. The other authors have no relevant financial interest in the products or companies described in this article.

Competing Interests

The views expressed in this article are those of the authors and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or US government.

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