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.

Common Brain Tumors: Ependymomas

GENERAL DESCRIPTION OF EPENDYMOMAS: Derived from cells that line the ventricles (fluid-filled brain cavities) and spinal cord central canal. Do not usually spread into normal brain tissue. Can block exits for cerebrospinal fluid and cause hydrocephalus. They constitute about 4% of all central nervous system tumors in adults and 10% of these tumors in children. About 30% of ependymomas develop in the spinal column.

Grade and Subtype

Descriptions of Subtypes

Usual Treatment

Low-grade (I).

Myxopapillary ependymoma (found in the spine).

Subependymoma (found in one of the ventricles).

No or very slow growth. In addition to grade, risk is also based on location of the tumor. Tumors on the spinal cord are more accessible than those in the fourth ventricle or in the middle of the lower back portion of the brain.

Can often be removed and cured with surgery, particularly those on spinal cord. Radiation may be needed. Chemotherapy (avoid radiation, if possible) in children under age 6).

Low-grade (II).

Papillary, cellular, and clear cell ependymomas.

Slow growth. Usually affect adults.

Surgery alone or followed by radiotherapy. For those who fail radiotherapy, possible use of nitrosourea-based chemotherapies or investigative drugs.

Grade III.

Anaplastic ependymomas.

Spreads to the spinal fluid.

Surgery followed by radiotherapy to brain and spinal cord. Possible shunt.

Grade IV.

Primitive neuroecto-dermal tumor (PNET). Composed of malignant forms of early, undeveloped nerve cells called neuroblasts. (This malignancy is also referred to as neuroblastoma.)

Very rare, but more common in children. Primitive nerve cells that grow very rapidly. Usually occur in cerebellum.

Surgery followed by radiotherapy to brain and spinal cord. Chemotherapy in young children. Investigative high-dose chemotherapy with stem cell rescue for children with relapsed cancer.

Common Brain Tumors: Oligodendrogliomas

DESCRIPTION OF OLIGODENDROGLIOMAS: They develop from oligodendrocyte glial cells. These cells form the protective coatings around nerve cells. Pure cell types are rare. Most often occur in mixed gliomas. Categorized as either low- or high-grade. Most are low grade II.

Description of Grade

Usual Treatment

Low Grade: Low grade difficult to tell from astrocytomas, although they are usually calcified. Very likely to bleed. Usually spread along nerve pathways of the brain and spine and rarely outside this area. In spite of difficulty in removing surgically, in some patients survival can be 30 - 40 years. Usually have better prognosis than astrocytomas of equal grade. Occur mostly in middle-aged adults, although there is also a small peak of incidence in children.

Treatment usually delayed until progression causes symptoms.

Surgery to remove whole tumor. Radiotherapy often follows in all adults over age 40 or in anyone in which tumor cannot be completely removed. Solid evidence is lacking on this approach, however, and there is some debate on its benefits.

Trials using chemotherapy after radiation are promising. Two-thirds of patients respond to PCV (combination of procarbazine, lomustine and vincristine.) Sustained remissions averaging 16 years often achieved. Pure oligodendrogliomas respond better than mixed gliomas. Temozolomide is showing promise as second-line treatment. Others under investigation.

Trials of additional chemotherapy for less well-differentiated tumors or for residual tumors after surgery.

High-grade. Anaplastic oligodendrogliomas.

Immediate treatment. Surgery to remove the whole tumor, if possible. Radiation typically follows surgery. Chemotherapy treatments either before or with radiation. Standard drugs are limited. Experts recommend trying investigative drugs. Temozolomide and retinoic acid may be useful. Possible additional drugs include melphalan, thiotepa, carboplatin, cisplatin, and etoposide.

(Numerous biologic markers may help identify specific oligodendrogliomas that will respond better or worse to specific treatments.)

Common Brain Tumors: Mixed Gliomas

GENERAL DESCRIPTION OF MIXED GLIOMAS: Mixed Glioma s contain a mixture of malignant gliomas. About half of these tumors contain cancerous oligodendrocytes and astrocytes.

Grade

Usual Treatment

Grade determined by the highest-grade cell present in the tumor.

Same as for oligodendroglioma.

Some Common Brain Tumors by Location

Brain Tumors

Description

Usual Treatment

Meningiomas

They are found in the membranes around the brain and spinal column. They are usually benign and rarely invasive. In such cases, long-term outlook is very favorable. (Malignant forms, anaplastic meningiomas, and hemangiopericytomas are uncommon and occur in about 2% of cases.)

Usually watchful waiting. Aggressive surgery the treatment of choice, if possible, although 20% recur after 10 years. Malignant forms and those at the base of the skull difficult to impossible to remove surgically. Stereotactic radiosurgery or fractionated external beam radiotherapy showing promising results for some patients.

Cerebellar astrocytomas (located in cerebellum)

Located in the cerebellum. Usually low-grade, but depends on cell type. If surgical removal is complete, up to 90% survival rates. More common in children than adults.

Surgery primary treatment. Radiotherapy if removal is incomplete.

Brain Stem Gliomas

About 60 - 70% of brain stem tumors are diffuse, which are likely to spread and have a rapid onset of symptoms. Focal tumors tend to be solid or cyst-like. They generally develop gradually. Occurs in both children and young adults.

Radiation is usual treatment. Tumors in this area are rarely removed surgically since the nerve tissue in this area is responsible for vital life functions. Slow-growing tumors may only require watchful waiting. Trials using advanced radiotherapy techniques, gene therapy, immunotherapy, and other experimental drugs.

Medulloblastomas

Occurs in cerebellum (the lower portion of the brain), brainstem, and spinal cord. Usually fast-growing aggressive cells. Most common brain tumors in children and young people, causing between 15 - 20% of brain tumors. With aggressive therapy, in children 5-year survival rates between 60 - 80%. In patients who survive for 2 years after diagnosis, long-term survival rate is nearly 80%.

Treatment is usually surgery and radiotherapy followed by chemotherapy. A 2005 study found that a combination chemotherapy regimen may replace radiation for very young children. A 2006 study suggested that radiation and chemotherapy doses should be adjusted based on disease severity.

Optic Tract Gliomas

Spread along the optic nerve. Usually slow growing. Most often in children under age 10. Children with these tumors often have vision and hormonal problems.

Usually surgery if one eye is involved. Possible chemotherapy or radiation.