Pediatric Brain Tumor Facts
*Content for the following section was compiled using data and statistics from the American Brain Tumor Association and the Children’s Brain Tumor Foundation
- 28,000 children in the U.S. are living with the diagnosis of a primary brain tumor
- Each year 3,750 children, 10 each day, are diagnosed with a pediatric brain tumor in the U.S.
- Even though survival rates for some childhood brain tumors have increased over the past 30 years, survivors often suffer lifelong side effects from their treatments
Brain tumors are the deadliest form of cancer in children and are fatal for almost half of the children diagnosed in the U.S. every year.
Medulloblastoma is the most common malignant childhood brain tumor, comprising 18% of all pediatric tumors. More than 70% of all pediatric medulloblastomas are diagnosed in children under the age of 10. About half of all medulloblastomas occur in children aged 5 or younger. Boys tend to develop the tumor more than girls at a rate of approximately two to one.
Long term effects of pediatric brain tumors and their treatment are devastating for survivors due to physical and psychological sequelae.
What is medulloblastoma?
— Neurocognitive problems
— Neurosensory problems
— Physical growth and endocrine problems
Progressive or recurrent disease
What is Medulloblastoma?
Most childhood tumors (more than 60%) are located in the posterior fossa (the back compartment of the brain which contains the cerebellum). Medulloblastoma (also called primitive neuroectodermal tumor or PNET) is a rapidly growing brain tumor that is found in the cerebellum. This area of the brain controls balance, posture, and complex motor functions such as speech and coordination.
Medulloblastoma is the most common malignant brain tumor in children (accounting for 18% of all pediatric tumors). It is an aggressive tumor and frequently spreads to the spine and meninges (the coverings of the brain) through the cerebrospinal fluid. It is unknown why this tumor has a tendency to spread outside its primary site of origin, the cerebellum.
Treatment is surgical removal, followed by radiation therapy of the entire head and spinal cord and/or chemotherapy
The cause of medulloblastoma is not yet known. Current research is focusing on understanding some of the possible genetic pathways that may be involved in the development of medulloblastoma. Scientists are also exploring normal brain activity pathways, such as communication patterns among cells or genes. Several therapies targeted at proteins in these pathways are being studied.
Symptoms may be caused by direct compression from the tumor on structures in the posterior fossa (brain stem and cerebellum) or due to blockage of cerebrospinal fluid resulting in secondary hydrocephalus. Hydrocephalus is an abnormal increase in the amount of fluid in the cerebral ventricles causing compression of the brain, potentially harming neural tissue.
The early “flu-like” symptoms of this tumor are often so non-specific that the disease first goes unnoticed. Children may experience headaches and vomiting (especially in the morning). Typically, the child feels better after vomiting and as the day progresses. As the pressure in the brain increases due to the growing tumor or hydrocephalus, the headaches and vomiting may increase. Since medulloblastoma appears in the cerebellum, problems with dizziness, coordination and progressive unsteadiness are quite common. Children with this tumor may exhibit a clumsy, staggering walk. They may also complain of visual problems especially if the tumor involves the sixth cranial nerve.
Diagnosis is usually made within one to three months of the onset of symptoms, as medulloblastoma is a very aggressive (fast growing) tumor. Magnetic resonance imaging (MRI), done both with and without contrast dye, is used to identify the presence of a tumor in the brain. While an MRI scan provides important details, microscopic examination of tissue obtained during surgical tumor removal, confirms the diagnosis.
Current treatment of medulloblastoma consists of surgically removing as much tumor as possible, followed by craniospinal (brain and spine) radiation and/or chemotherapy.
Analysis of the tumor tissue will then identify the stage of the tumor.
The oncologist will suggest a treatment plan based on risk factors for tumor recurrence. Children are classified as either “average-risk” or “high-risk.” Risk is determined by the age of the patient, the amount of tumor remaining after surgery, and the amount of tumor spread, or metastasis (also referred to as M stage).
Children are considered at “average-risk” if they are diagnosed after the age of 3; if all, or nearly all, of the tumor is removed; and if there is no evidence of metastasis. All other children are considered to be at “high-risk.” High–risk patients are those under the age of 3; have more than 1.5 cm squared of tumor volume remaining after surgery; or have tumor spread.
M0 no evidence of metastasis
M1 tumor cells are present in the cerebrospinal fluid
M2 tumor is present beyond the primary site (cerebellum), but still isolated to the brain
M3 tumor is present in spine
M4 tumor has spread to areas outside of the central nervous system (this is rare)
After a diagnosis of medulloblastoma has been made, it is critically important to remove as much of the tumor as possible. During surgery, the neurosurgeon will try to 1) relieve cerebrospinal fluid buildup caused by the tumor and 2) remove as much tumor as possible with minimal neurological damage. The removed tissue will then be analyzed to determine the type of tumor and the staging. The best chance of long-term survival is when all of the tumor visible to the naked eye can be removed safely.
While the goal is to completely remove the tumor, some medulloblastomas cannot be removed entirely. Sometimes the tumor grows into the brainstem, making total removal difficult because of the risk of neurological damage.
After tumor resection surgery, a temporary external drainage device (an extraventricular drain) may be placed to divert excess cerebrospinal fluid from the brain. In approximately 15% of children diagnosed with medulloblastoma hydrocephalus may continue, requiring surgical placement of a permanent shunt to drain spinal fluid from the brain into the peritoneal cavity. This type of device is called a ventriculoperitoneal shunt (commonly referred to as a VP shunt).
However, in the majority of cases, removing the tumor opens the cerebrospinal fluid pathways, which restores both normal fluid flow and intracranial pressure and therefore, eliminates the need for a shunt.
Within a couple of days of surgery, an MRI will be done to see the amount of remaining tumor. This will be a strong factor in determining further treatment.
Post-operatively some children may have difficulties related to coordination, weakness in their extremities and imbalance. These typically resolve over the course of several weeks with the help of physical and occupational therapy.
About 25% of children undergoing surgery for their tumor developed cerebellar mutism, a delayed onset loss of speech which is often associated with decreased muscle tone and unsteadiness. This syndrome seems to occur predominantly after surgery in children with medulloblastoma, and has not been clearly related to tumor size or surgical approach. Children with this impairment seem to awaken relatively well from surgery and may say a few words. However, within 24-48 hours, it becomes obvious that the child is unable to speak and has associated deficits including decreased muscle tone, difficulty reaching for objects, swallowing difficulties, and marked irritability.
Recovery from cerebellar mutism may happen in as few as 6 days or as long as 52 months. There have been no cases reported where a child with cerebellar mutism did not get return of functional speech. Children who have developed cerebellar mutism should begin therapy with a speech-language pathologist.
After surgery, medulloblastoma is usually treated with radiation therapy. It is an important step because microscopic tumor cells can remain in the brain tissue after surgery. These remaining cells can lead to tumor re-growth. Radiation is used to destroy these left over cancer cells to prevent further spread.
Radiation therapy involves aiming beams of X-rays at the tumor in exactly prescribed doses. It is often given over a 6 week period involving treatment 5 days a week. Radiation kills the tumor cells by destroying their ability to divide and thus multiply. Just as it is able kill a tumor cell it also has the ability to harm normal tissue near the tumor, or along the path of the beam traveling in and out of the body, as well as cells of the immune system.
Side effects of radiation therapy can include brain swelling, fatigue, hair loss, skin irritation, nausea and vomiting.
Newer radiation therapies include intensity modulated radiation therapy (IMRT) and proton –beam as well as stereotactic (precisely focused), conformal (regionally focused), and hyperfractional (split-dosing) techniques. The goal with these therapies is to provide the safest maximum dose of radiation to the tumor cells while sparing all healthy cells and tissues around the tumor from harm.
Several factors are taken into consideration when planning radiation therapy. Since radiating the brain and spine can be damaging to a developing brain, it is usually delayed in children less than 3 years of age. For older children, radiation therapy is given to the craniospinal axis (both the brain and spine). A “boost” is given to the posterior fossa, the region most at risk because it housed the original tumor. An additional radiation boost may be given to areas of tumor spread.
Chemotherapy is the use of powerful drugs to slow down or kill rapidly dividing tumor cells. Like radiation, they can also kill beneficial cells and have side effects such as nausea, vomiting, fatigue, infection, bleeding, and hair loss.
For children with medulloblastoma, chemotherapy is used to reduce the risk of tumor cells spreading through the spinal fluid. Because different drugs are effective during different phases of a cell’s life cycle, a combination of drugs may be given. Please note that the chemotherapy protocol will be specific to each individual child.
As Medulloblastoma is so rare, most children will be able to participate in clinical trials-organized studies that are helping to determine which treatments are most effective.
There are several treatment plans in use, but most focus on a combination of vincristine, cisplatin, etoposide, lomustine, and/or cyclophosphamide.
Some treatment plans use higher doses of chemotherapy, supported by peripheral stem cell rescue for children under the age of 3. This is used to delay or even eliminate the need for radiation therapy. There is also interest in instilling chemotherapy directly into the cerebrospinal fluid (either into the lumbar spine by a spinal tap or into the ventricles of the brain by an Ommaya reservoir). This is being done in an attempt to deliver high doses of the drugs to the coating regions of the brain and reduce disease relapse.
Long term effects
Despite its impact on increasing survival, the tumor and its treatment can cause significant late effects. These problems may occur months to years after therapy has ended. Whether or not a child will develop a late effect depends on a number of factors. The most important factors being the type of treatment the child received (specific chemotherapy drugs and radiation) and the child’s age at the time of treatment.
Late effects may be mild and easily treated such as an under active thyroid to severe and life threatening such as a second, new cancer.
Because of the amount of radiation and chemotherapy involved, the number of adverse treatment outcomes in survivors of pediatric medulloblastoma can be extensive.
Survivors of childhood brain tumors frequently develop difficulties such as a decrease in IQ, or intellectual ability, learning disabilities, attention deficit, and memory loss.
A patient’s age at the time of treatment can be a major factor in determining the future quality of life. The younger the child during treatment, the greater the potential subsequent learning challenges.
Learning disabilities are particularly common among brain tumor survivors, and many children require special education services at school. It is not uncommon for these children to demonstrate deterioration in function over time, particularly in children who were treated with radiation to the brain at a young age. It is very important to reassess cognitive functioning periodically in all survivors who are at risk or who experiencing academic difficulties. These tests are known as psychometric or neuropsychological assessments.
It is now mandated by federal law that if problems are identified, then the child’s school must provide your child with appropriate services. However, you and the members of your child’s medical team may need to advocate for your child to get all of the services that they are entitled to.
Learning problems are clearly among the most difficult and frustrating problems facing young brain tumor survivors, but new areas of research such as cognitive rehabilitation offer hope for the future.
Hearing loss is common after treatment for brain tumors. Occasionally, hearing loss progresses years after treatment ends. Children who receive cisplatin (a chemotherapy drug) and radiation to the brain appear to be at the greatest risk for developing delayed hearing problems. Periodic hearing tests should be performed on all children who are at risk as well as those who may be experiencing academic or learning difficulties.
Radiation can have long term effects on endocrine function which is responsible for hormone production. The hypothalamus and pituitary glands, both important for bodily function and growth are commonly affected. Patients may have problems with obesity, fertility dysfunction and thyroid problems.
Physical growth and endocrine problems
Growth hormone deficiency is the most common pituitary problem seen after radiation to the brain. Growth hormone is essential for physical growth and children who are deficient in growth hormone grow slowly and may be of short stature when they reach adulthood. It also affects bone strength, cholesterol levels, amount of body fat, and stamina. Children who also receive radiation to the spine may experience severe growth problems.
Another issue that these long-term survivors have to face is the possibility of secondary malignancies due to the effects of radiation and chemotherapy.
Guided-imagery uses the power of a soothing voice and your child’s imagination to help your child’s coping with anxiety and pain during a procedure. Using a peaceful images and sounds while gently stroking your child’s hand and arm, can lead a child into a calm state of mind, drawn completely into the image you have provided for them. Some children have reported guided imagery helping them with nausea, anxiety, and lengthy MRI scans.
Laughter. The average child laughs 400 times a day. Humor has both positive psychological and physical affects and may serve as a coping strategy for your child by reducing feelings of fear, anxiety, and pain.
Massage therapy can have an important role in supporting the well-being of your child through illness and recovery. It can involve only a part of the body or a full body massage. A foot massage while receiving chemotherapy can be extremely relaxing and can immediately reduce feelings of nausea. Research has shown that massage therapy can help decrease anxiety, depression, insomnia, physical discomfort, and help with side effects of medications.
Music therapy has the ability to assist with emotional, physical and spiritual health and to enhance quality of life. Music promotes relaxation and may assist in pain management as well as decrease anxiety, depression, and fear.
Children going through treatment for cancer need to have moments of normalcy, empowerment, and opportunities to increase their self-expression. Music can help these children find that place and just be a kid.
Progressive or recurrent disease
Tumors recur when all of the tumor cells cannot be removed by surgery or destroyed by other treatments. In children, medulloblastoma tends to “seed” or drop tumor cells into the spinal fluid. These cells can give rise to tumor growth in the spine and other areas of the brain.
In the case of relapse, there has not been shown to be an effective curative therapy. . Recurrences limited to the cerebellum (the posterior fossa) offer the best chance of long-term survival. Treatment of recurrent medulloblastoma is aggressive and may include repeated surgery, re-irradiation if possible, and chemotherapy.
MRI scans of the brain will be done every 2-3 months and spinal MRI every 4-6 months for the two years following surgery. Scans will be performed less frequently thereafter.
The follow up of patients with medulloblastoma consists of yearly evaluations by the multidisciplinary team with detailed physical and neurological examinations, audiologic evaluations, endocrine assessments, and neuropsychologic testing.
Children should be carefully evaluated for long-term cognitive problems and should receive early aggressive learning support.
Rehabilitation and special education programs will play a vital role in returning children to school.
Prognosis is affected by the child’s age at the time of diagnosis; the size and extent of the tumor; the amount of tumor that was removed; and the level of metastatic disease.
With current therapies, 70-80% of children with average-risk medulloblastoma will be alive in 5 years. Even in those children considered high-risk, effective therapy is possible and results in long term disease control in as high as 60-65% of patients. Outcomes for children less than 3 years of age are much poorer, but if the disease is restricted to the cerebellum at the time of diagnosis, survival rates in the 30-50% range are being seen. Over the past decade, there has been increasing evidence that chemotherapy improves survival for children whose tumor is only partially removed, or has spread beyond the primary site (disseminated) at diagnosis.
For children who are very young or have disseminated disease at diagnosis, where the tumor has spread to the spine and/or the surface of the brain (leptomeningeal disease) survival is not as good.