Glioma

MRI of the brain with and without gadolinium contrast is the primary diagnostic imaging modality.

Advanced MRI techniques including MR spectroscopy, perfusion imaging, and diffusion tensor imaging may provide additional information about tumor grade and extent.

Histopathological examination of tumor tissue obtained by stereotactic biopsy or surgical resection is required for definitive diagnosis. The 2021 WHO classification mandates comprehensive molecular profiling, which are integral to both diagnosis and treatment planning.

Under the current WHO classification, gliomas are graded from 1 to 4. Grade 1 tumors are largely circumscribed and behave in a benign fashion, with surgical resection often curative. Grade 2 tumors are diffusely infiltrating and carry a risk of malignant transformation over time, particularly in the absence of favorable molecular markers. Grade 3 tumors show increased mitotic activity and a more aggressive biological course. Grade 4 glioblastoma is the most malignant glioma, characterized by rapid progression and uniformly poor prognosis despite aggressive treatment.

For grade 1 gliomas, complete surgical resection is often curative, and adjuvant treatment is not routinely required. For grade 2 to 4 tumors, treatment typically follows a multimodal approach. Maximal safe surgical resection — achieving the largest possible tumor removal without causing neurological deficits — is the initial goal, as greater extent of resection is associated with longer survival across all grades. Intraoperative tools including neuronavigation, fluorescence-guided surgery, and neurophysiological monitoring help surgeons maximize resection while protecting eloquent brain tissue.

Following surgery, standard treatment for glioblastoma consists of concurrent radiotherapy with chemotherapy. Tumor treating fields (TTFields), a modality using alternating electric fields delivered via scalp transducer arrays, may be used in addition to standard chemotherapy in selected patients. Lower-grade gliomas are managed with radiotherapy and/or chemotherapy with regimens tailored to molecular subtype and clinical risk factors. All patients require lifelong MRI surveillance given the risk of recurrence.