Questions About Cancer? 1-800-4-CANCER

Childhood Brain Stem Glioma Treatment (PDQ®)

Health Professional Version
Last Modified: 11/01/2011

Treatment Option Overview

Many of the improvements in survival in childhood cancer have been made as a result of clinical trials that have attempted to improve on the best available, accepted therapy. Clinical trials in pediatrics are designed to compare new therapy with therapy that is currently accepted as standard. This comparison may be done in a randomized study of two treatment arms or by evaluating a single new treatment and comparing the results with those that were previously obtained with existing therapy.

Because of the relative rarity of cancer in children, all patients with brain tumors should be considered for entry into a clinical trial. To determine and implement optimum treatment, treatment planning by a multidisciplinary team of cancer specialists who have experience treating childhood brain tumors is required. Radiation therapy (including 3-dimensional conformal radiation therapy) of pediatric brain tumors is technically very demanding and should be carried out in centers that have experience in that area in order to ensure optimal results.



Glossary Terms

3-dimensional conformal radiation therapy (3-dih-MEN-shuh-nul kun-FOR-mul RAY-dee-AY-shun THAYR-uh-pee)
3-dimensional conformal radiation therapy involves the use of computed tomography (CT) imaging in the planning of radiation therapy. The CT scan provides not only 3-dimensional imaging of the target and surrounding normal tissues, but also information about tissue density and tissue depth from the skin to the target. These parameters are critical in calculating the dose distribution. In addition to CT imaging, supplemental imaging modalities, such as magnetic resonance imaging or positron emission tomography, can be used to improve target delineation. With 3-dimensional conformal radiation therapy, conformal beams are used to shape the dose delivered to the target, and wedges or compensators can be used to optimize the dose distribution. Conformal beams are shaped either with a high-density material (e.g., Cerrobend) that allows beam contouring or with multi-leaf collimators, which are an array of high-density leaves (usually tungsten) situated in the head of the linear accelerator (LINAC) whose position is controlled via independent stepping motors that allow beam shaping. Wedges are high-density devices that are placed on the head of the LINAC to act as a tissue compensator and/or beam modifier. The effect of a wedge can be created by a moving jaw at the head of the LINAC. With 3-dimensional conformal radiation therapy, variable field weighting and/or use of different energies (higher energies are more penetrating) are additional tools that enable optimization of the dose distribution. Also called 3-dimensional radiation therapy and 3D-CRT.