Prognostic Factors for Brain and Spinal Cord Tumors in Children

Why aren't brain and spinal cord tumors staged like other cancers?

For most types of cancer, the stage – a measure of how far the cancer has spread – is one of the most important factors in selecting treatment options and in determining a person's outlook (prognosis).

But tumors of the brain and spinal cord differ in some important ways from cancers in other parts of the body. One of the main reasons other types of cancer are dangerous is that they can spread throughout the body. Tumors starting in the brain or spinal cord can spread to other parts of the central nervous system, but they almost never spread to other organs. These tumors are dangerous because as they grow, they can interfere with essential functions of the brain.

Because most tumors in the brain or spinal cord do not usually spread, they do not have a formal staging system like most other types of cancer.

What factors can affect prognosis?

While these tumors aren't staged, there are other important factors that can help determine a child’s prognosis. These include:

• The type of tumor (such as astrocytoma, ependymoma, etc.)
• The grade of the tumor (how quickly the tumor is likely to grow, based on how the cells look under a microscope)
• The location and size of the tumor
• How much of the tumor can be removed by surgery (if it can be done)
• Whether the tumor cells have certain gene mutations or other changes
• The child’s age
• The child’s functional level (whether the tumor is affecting normal brain functions and everyday activities)
• Whether or not the tumor has spread through the cerebrospinal fluid (CSF, the fluid around the brain and spinal cord) to other parts of the brain or spinal cord
• Whether or not tumor cells have spread beyond the central nervous system

If your child has a brain or spinal cord tumor, talk to the treatment team to learn more about how these and other factors might affect your child’s outlook and treatment options.

Risk groups for medulloblastoma

Medulloblastomas are one of the most common types of brain tumors in children. Many clinical trials for treating medulloblastoma use a system that places children into either standard-risk or high-risk groups, based on certain factors. Children are placed in the high-risk group if any of these apply:

• The child is younger than 3
• A lot of the tumor can’t be removed during surgery
• Tumor cells are in the CSF or have spread to other parts of the brain or elsewhere

Doctors are still refining this system to make it as accurate as possible.

Along with these risk groups, medulloblastomas can also be grouped based on: 

• How the tumor cells look under a microscope
• Whether the cells have certain gene changes 

For example, based on gene changes, medulloblastomas can be divided into 4 types. Some of these tend to have a better outlook, so doctors may be able to use this to better tailor the treatment each child gets. (See What’s New in Research for Brain Tumors in Children?)