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  • Updated 03.01.2024
  • Released 03.06.2022
  • Expires For CME 03.01.2027

Astrocytoma IDH mutant, WHO grade 2



This article discusses isocitrate dehydrogenase (IDH)-mutant astrocytoma, World Health Organization (WHO) grade 2, including its classification, natural history, and management options.

Key points

• Astrocytoma IDH mutant, WHO grade 2, presents with a wide spectrum of neurologic manifestations.

• The median age at presentation is in the 40s, with a slightly higher incidence in males.

• Magnetic resonance imaging with and without contrast is the standard approach for evaluating brain lesions.

• Tissue diagnosis by biopsy or surgery is essential.

• Extent of resection is associated with outcomes.

• Radiation and chemotherapy prolong survival, but the exact timing is not well delineated.

• Inhibitors of mutant isocitrate dehydrogenase hold promise for improved progression-free survival.

• Observation may be a reasonable option for select cases, keeping in mind that regular imaging is needed in this setting.

Historical note and terminology

Brain tumors were managed historically with surgical resection and radiotherapy starting in the era of Harvey Cushing. In 1976, adjuvant chemotherapy began to be utilized when cyclohexyl chloroethyl nitrosourea (CCNU) was found to increase survival—albeit by only a few months (14). During this era, our understanding and classification of gliomas was based entirely on histology and anatomical location of the tumors. This approach continued until 2016 when a new classification system was developed, guided by a new molecular understanding of gliomas. In particular, mutations in the genes encoding isocitrate dehydrogenase (IDH1 and IDH2), as well as chromosomal 1p/19q co-deletion were found to be strongly associated with improved prognosis (40; 55; 45). The 2021 World Health Organization (WHO) classification further refined the classification system to include the following glioma subtypes:

• Astrocytoma, IDH-mutant
• Oligodendroglioma, IDH-mutant and 1p/19q-co-deleted
• Glioblastoma, IDH-wildtype (28)

Although the 2021 WHO classification emphasizes the tumor molecular features, the tumor grade continues to play a role in clinical studies and patient care. The focus of this article is on astrocytoma IDH mutant, WHO grade 2.

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