The brain
Pilocytic astrocytoma is a low-grade, benign brain tumor most commonly found in children ages 5 to 15. It is a slow-growing noninvasive type of tumor arising from astrocytes, but it can become quite large. Astrocytomas arises from astrocytes, which are star-shaped glial cells found throughout the central nervous system. This tumor is often associated with neurofibromatosis type 1, a genetic disorder that results in multiple or recurrent tumors, especially of the optic nerve.
Indications
According to the National Cancer Institute (see References), treatment depends on the size and location of the tumor. The most common tumor site is the cerebellum, the area of the brain that controls coordination and balance, but tumors can also occur in other areas, such as near the optic (vision) nerves, in the cerebrum or in the brain stem. Even though this tumor is not malignant, it can cause severe problems as it grows and presses on brain structures, causing gait disturbances, headaches and vision disturbances, nausea and vomiting. Most pilocytic astrocytomas grow in areas that are easily reached for surgery, and they are often cystic with sharp borders, making it easy to remove the entire tumor.
Surgery
Surgical removal for children and young adults is by open surgery or radiosurgery (GammaKnife or CyberKnife), which can focus high-dose radiation directly on tumor tissue without damage to surrounding brain tissue. Radiosurgery is appropriate only for small tumors. If the complete tumor is removed, usually no further treatment is indicated. The National Cancer Institute reports that up to 95 percent of cerebellar astrocytomas in children can be surgically removed, but removal might be more difficult at other sites. If a pilocytic astrocytoma has grown and spread, then complete surgical removal might be impossible and some residual tumor may remain, indicating a need for radiation therapy, which can include radiosurgery if the remaining tumor is identified.
Radiation and Chemotherapy
According to the National Cancer Institute, some doctors advise radiation therapy shortly after open surgery if a residual tumor is observed or suspected, but often radiation is delayed until there is evidence of recurrence or tumor growth. For a young child, chemotherapy might be used to delay radiation therapy for tumors that cannot be removed. Adults tend to have more recurrence, but are treated similarly with surgery and radiation therapy as needed. In both cases, if there is recurrence after surgery and radiation, chemotherapy may be used. There are ongoing clinical trials to determine the best protocol for treatment. Routine screening, usually done yearly, is done after surgical removal or radiation therapy to determine whether the tumor has returned or spread. Monitoring is especially important if there is residual tumor in the brain or if the tumor could not be surgically removed.
Tags: radiation therapy, Cancer Institute, National Cancer, National Cancer Institute, residual tumor