Surgery Insight: The Role of Surgery in the Management of Low-Grade Gliomas

Table 1.

Table 1: Large Studies Investigating the Effect of Surgical Resection on Outcomes of Low-grade Glioma

As an organization accredited by the ACCME, Medscape, LLC requires everyone who is in a position to control the content of an education activity to disclose all relevant financial relationships with any commercial interest. The ACCME defines "relevant financial relationships" as financial relationships in any amount, occurring within the past 12 months, including financial relationships of a spouse or life partner, that could create a conflict of interest.

Medscape, LLC encourages Authors to identify investigational products or off-label uses of products regulated by the US Food and Drug Administration, at first mention and where appropriate in the content.

Author(s)

Nader Pouratian, MD

Neurosurgical Resident, University of Virginia, Charlottesville, Virginia

Disclosures

Disclosure: Nader Pouratian, MD, has disclosed no relevant financial relationships.

Ashok Asthagiri, MD

Staff Clinician, University of Virginia, Charlottesville, Virginia

Disclosures

Disclosure: Ashok Asthagiri, MD, has disclosed no relevant financial relationships.

Jay Jagannathan, MD

Resident in Neurosurgery, University of Virginia, Charlottesville, Virginia

Disclosures

Disclosure: Jay Jagannathan, MD, has disclosed no relevant financial relationships.

Mark E. Shaffrey, MD

Professor and Chairman of Neurosurgery, University of Virginia, Charlottesville, Virginia

Disclosures

Disclosure: Mark E. Shaffrey, MD, has disclosed no relevant financial relationships.

David Schiff, MD

Medical Neuro-Oncologist and Professor, University of Virginia, Charlottesville, Virginia

Disclosures

Disclosure: David Schiff, MD, has disclosed no relevant financial relationships.

processing....

Epidemiology

The phrase 'low-grade gliomas' encompasses the entire spectrum of WHO grade I and II gliomas, which includes ependymomas, pilocytic astrocytomas, pleomorphic xanthoastrocytomas, diffuse astrocytomas, oligodendrogliomas, and mixed gliomas. Although arbitrarily clustered under the umbrella low-grade glioma nomenclature, this heterogeneous group of tumors is clinically, histologically and molecularly diverse, and is, therefore, not generally studied or discussed as a single entity. For example, WHO grade I lesions, which include pilocytic astrocytomas and gangliogliomas, are, unlike WHO grade II lesions, well circumscribed and noninfiltrative, and complete surgical resection is universally considered curative.^[1] In this Review, we will limit our discussion to WHO grade II diffuse astrocytomas, oligodendrogliomas and oligoastrocytomas, all of which have similar invasive and malignant potential.

Although low-grade gliomas are less common than malignant gliomas (of which there are ~8,000 - 10,000 cases per year) and far less common than brain metastases (~75,000 - 150,000 cases per year), they are far from rare. Approximately 2,000 - 3,000 low-grade gliomas are diagnosed in the US every year, accounting for nearly 15% of all primary brain tumors.^[2] According to the Central Brain Tumor Registry of the United States (CBTRUS), the various histological classes of low-grade glioma have incidences varying between 0.10 and 0.46 per 100,000 people, and a cumulative incidence of approximately 0.9 per 100,000 people.^[2]

Despite the preponderance of astrocytomas, there has been an apparent increase in recent years in the incidence of pure oligodendrogliomas and of mixed oligoastrocytomas. This increase might be partly attributable to an increased tendency for neuropathologists to seek out such diagnoses, in view of the relatively favorable prognosis conveyed by an oligodendroglial component.^[3] Low-grade gliomas are particularly prevalent among white people and among men, and the highest incidence is in people between 35 and 44 years of age. Low-grade astrocytomas in adults are most commonly located in the cerebral hemispheres, with a predilection for 'secondary' functional areas such as the supplementary motor area and the insular lobe.^[4] Oligodendrogliomas are most commonly seen along the cerebral convexity in subcortical areas, particularly in the frontal lobe, but sporadic reports of posterior fossa oligodendrogliomas exist.