Disease Information

Brain Tumor: Infant Brain Tumors

Definition

Types of brain tumors in young children
Medulloblastoma and ependymal tumors account for about 50 percent of tumors. Most of these tumors likely develop after birth. They peak in incidence before age 5. Atypical teratoid / rhabdoid and choroid plexus tumors are most commonly found in children younger than 2.

Incidence

Primary tumors of the central nervous system account for about 8 percent of cancer in infants and 3 percent of malignant tumors observed in newborns.

Influencing Factors

Children younger than 3 who are diagnosed with brain tumors are particularly challenging to treat. Brain tumors in young children tend to grow quickly  and their prognosis usually is much poorer than for older patients. Medulloblastoma tumors are prone to spread throughout the brain and spine. Treatment approaches must focus on controlling not only local disease but disease in all sites of the nervous system. This often requires treatment to be aimed at the entire nervous system in the young child and heightens the likelihood of treatment-related brain injury.

Clinical Features and Symptoms

For infants, the most common symptom is rapidly expanding head size and bulging fontanel (membrane covered opening in an infant’s skull.) Because of the expandability of the skull of an infant, symptoms of intracranial pressure, other than vomiting, are rare in infants.

Treatment Strategies

Drawbacks of traditional therapy

• Radiation is generally an effective treatment for brain tumors, but can cause devastating harm in the developing brains and nervous systems of children younger than 3. The first three years of life are extremely important in physical, mental, and emotional development. Children who receive radiation therapy to the brain may experience major problems with thinking, learning, and growing. According to a National Cancer Institute survey of cancer survivors, 70 percent of brain tumor survivors who were younger than 3 when diagnosed require special education or learning-disabled classroom settings.
• It has been standard therapy to give chemotherapy drugs in an attempt to delay giving radiation therapy until the child is older and thus giving the brain more time to develop. However, chemotherapy alone has not been effective in fighting brain tumors. Treating brain tumors with chemotherapy is different from treating tumors elsewhere in the body. The brain has a natural defense system not present in other organs of the body. That system, called the blood-brain barrier, protects the brain from foreign substances by blocking their passage from the blood. For a drug to be effective in treating brain tumors, a sufficient quantity must either pass through the blood-brain barrier or bypass it entirely.

Based on the experience gained in several studies at St. Jude, researchers have designed a new approach to the treatment of children younger than 3. It includes intensive chemotherapy as well as the early and planned use of smaller and more confined fields of radiation therapy. The use of conformal radiation therapy allows more tightly focused radiation with less of a dose delivered to surrounding healthy brain tissue.

Current Research

• Scientists continue to study chromosomal abnormalities, genes, and proteins that may have a role in the development and metastasis (spread to other parts of the central nervous system) of brain tumors in children younger than 3. Infants and very young children have brain tumors that are apparently unique to the early childhood years. Some of these tumors, such as atypical teratoid tumors and choroid plexus tumors, although rare, are a significant problem in the pediatric age range. Research into brain tumors affecting older populations will likely not address these types of brain tumors. Studies of the mechanism of their development may also lead to important insights into general brain development. Similarly, studies of brain development may lead to insights into the neurobiological aspects of tumors of infants.
• Clinical trials are underway to develop chemotherapy drugs effective against these tumors.
• Clinicians continue to look for therapies that provide better disease control and lessen short-term and long-term side effects.

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