Surgery

Surgery has many uses in the treatment of brain cancers. It is used to get a sample of tissue to confirm the diagnosis, remove as much of the tumor as possible, or alleviate symptoms. For some brain tumors, surgery is used to place a shunt to drain fluid from the brain. There are some instances when surgery is not possible due to the location of the tumor and the damage that would be done to the child’s ability to function by trying to remove it. After surgery for brain tumors, physicians classify, grade, and stage the tumor before deciding on what further treatment, if any, is necessary. Each step of this process is explained in the following list:

• Classification. A pathologist looks at a sample of the tumor under a microscope to determine the origin of the tumor cells. For instance, tumors that arise from glial cells in the brain are ependymomas, astrocytomas, and oligodendrogliomas.

• Grading. The pathologist estimates the degree of the malignancy by studying many different features of the tumor cells. Numbers are used to describe the aggressiveness of the tumor, with the higher numbers being the more aggressive. Aggressive means they will grow and spread if left untreated.

• Staging. Before surgery, the extent of the tumor spread is evaluated using scans. During surgery, the neurosurgeon decides whether the tumor can be completely removed (called resected) and whether other tumors are present. For most tumors, doctors recommend a lumbar puncture to check for cancer cells in the cerebrospinal fluid. The doctor will determine how many additional studies, if any, are needed after surgery to stage the tumor.

After the tumor has been classified, graded, and staged, the oncologist gives recommendations for treatment.

Radiation

Radiation therapy—directing high-energy x-rays at tissue—is frequently used for brain tumors. In most cases, the radiation is directed at the tumor itself, sparing surrounding healthy tissue as much as possible. For extremely malignant tumors, the entire cranium and sometimes the spine are irradiated to destroy any cancer cells that have broken off from the main tumor and lodged elsewhere.

To minimize damage to healthy brain cells, 3-dimensional conformal radiation therapy or charged-particle radiation therapy (such as proton beam therapy) are being used at many cancer treatment centers around the country. Research is on-going in studies of these new methods of radiation therapy and the acute and long-term effects in children. Studies have shown encouraging results with improved survival rates and decrease in incidence and severity of late effects. More research is needed to continue to observe long-term results and late effects of new methods of radiation such as proton beam therapy.

Radiation is generally given in many doses (called fractions) over a period of time. The length of radiation treatment and the amount of radiation given varies depending on the type of tumor, its location in the brain, and the child’s age. Because of the critical brain growth that would be disrupted in young children, doctors try to postpone or avoid using radiation until children are at least 2-years-old.

Chemotherapy

Chemotherapy has variable effectiveness against brain tumors because the blood-brain barrier prevents many types of chemotherapy from penetrating brain tumors. In some cases, chemotherapy is used in very young children to slow the progression of their disease until radiation can be given with fewer long-term side effects. In other cases, chemotherapy is one of the front-line treatments used to cure disease.

Stem cell transplantation

Autologous bone marrow transplants and peripheral blood stem cell transplants have been used with increasing frequency to treat children with high-risk or relapsed brain tumors. See descriptions of the types of stem cell transplants and late effects in section at the end of this chapter, Stem Cell Transplantation Late Effects.