Brain Tumors: Primary - Common Brain Tumors

Common Brain Tumors: Astrocytomas

GENERAL DESCRIPTION OF ASTROCYTOMAS: Derived from star-shaped glial cells called astrocytes.

Grade and Subtype

Description of Subtypes

Usual Treatment

Low-Grade (Usually I) Astrocytomas.

Pilocytic gliomas.

Pilocytic gliomas occur mostly in children. Tumors are well differentiated. Cells are relatively normal and rarely metastasize. They grow relatively slowly.

Pilocytic astrocytomas have the highest 5-year survival rates (greater than 70%). However, even well differentiated astrocytomas are life threatening if they are inaccessible.

Cancer may sometimes be completely removed through surgery, particularly if it occurs in the cerebellum.

For recurrence or residual tumors, reoperation, radiotherapy, or chemotherapy may be given, depending on the circumstances. Repeat surgery for cerebellar astrocytoma is often very successful. For those who fail radiotherapy and chemotherapy, investigative drugs are used.

Low-Grade (II) Astrocytomas.

Fibrillary, protoplasmic, and protoplasmic astrocytomas. Some pleomorphic xanthoastrocytomas.

Tumors are well differentiated. Cells are relatively normal and less malignant than those in higher grades. They grow relatively slowly but can spread. Survival rates average 5 years, but people can survive for a decade or more.

Pleomorphic xanthoastrocytomas have a relatively favorable prognosis, but can recur and demonstrate aggressive clinical behavior.

Low-grade astrocytomas generally occur in young adulthood, with a peak incidence in 30s and 40s.

Surgery, if possible, plus radiotherapy. Surgery alone in certain children, if possible. Trials on postoperative radiotherapy include the following: radiotherapy with or without chemotherapy; low-versus-high radiotherapy doses (studies suggest results are the same and high-dose causes more side effects); Deferring radiotherapy until tumor progresses and symptoms occur. (A major 2002 study confirmed earlier ones that suggest that this approach has the same 5-year survival benefits -- about 65% -- as immediate postoperative radiotherapy.)

Malignant (High-grade III and IV) Astrocytomas. Anaplastic astrocytoma (gemistocytic and some pleomorphic xanthoastrocytomas). Usually mid-grade (III).

Tumors grow more rapidly than lower grades and infiltrate other nearby healthy cells. Not well-differentiated. Five-year survival rates are about 30%. Recurrence is common.

Treatment same for all high-grade malignant astrocytomas.

Surgery, with removal of as much of tumor as possible followed by radiotherapy, with or without chemotherapy.

The addition of chemotherapy, particularly being able to take more than 6 cycles, appears to improve survival rates. Carmustine (BCNU) most effective drug at this time. Other drugs and treatment sequences are under investigation. For example, temozolomide is showing promise for many patients, including the elderly. Topotecan may also be useful with other drugs or with radiation.

For recurring gliomas, surgery with placement of wafers that release carmustine (Gliadel wafers) is the only proven beneficial therapy to date. Combinations, such as procarbazine and carmustine, provide benefits for recurrent anaplastic astrocytomas. Single drugs may be less toxic and as helpful for other recurrent gliomas. Temozolomide has been approved in Europe for high-grade recurrent gliomas and is proving to be beneficial. Other trials include the following: drugs that block small molecules involved in tumor growth; radioimmunotherapy using monoclonal antibodies; advanced radiotherapy techniques; intraarterial chemotherapy.

High-grade (IV and V).

Glioblastoma (notably glioblastoma multiforme or GBM).

Very rapidly growing tumors that spread quickly. Represents about 25% of all primary brain tumors. Most common in older adults (over age 55) and affect more men than women. Recurrences are common in patients who achieve long-term survival.