(Tumores cerebrales)

Brain tumors are the most common solid tumors of childhood, as common as leukemia.

There are tremendous differences among brain tumors in children; some have a very poor outlook while others can be cured with surgery alone. These differences can make understanding pediatric brain tumors, and finding the right treatment for each one, confusing.

What Is a Brain Tumor?

A tumor is any mass caused by abnormal or uncontrolled growth of cells. Tumors in the brain are categorized according to several factors, including where they're located, the type of cells involved, and how quickly they're growing.

Medical terms doctors may use to describe brain tumors include:

• Low-grade vs. high-grade: Usually, low-grade tumors are slow-growing, while high-grade tumors are fast-growing and aggressive. High-grade tumors can invade nearby tissue or spread elsewhere in the body, and are more likely to recur after treatment. They are generally associated with a worse outlook.
  
• Localized vs. invasive: A localized tumor is confined to one area and is generally easier to remove, as long as it's in an accessible part of the brain. An invasive tumor has spread to surrounding areas and is more difficult or impossible to remove completely.
  
• Primary vs. secondary: Primary brain tumors originate in the brain. Secondary brain tumors are made up of cells that have spread (metastasized) to the brain from somewhere else in the body. In children, most brain tumors are primary.

What Causes a Brain Tumor?

Like all tumors, brain tumors originate when a normal cell begins to grow abnormally and multiply too quickly. Eventually these cells develop into a mass called a tumor. The exact cause of this abnormal growth is unknown, though research continues on possible genetic and environmental causes.

Some kids who have certain genetic conditions have a greater chance of developing brain tumors. Diseases such as neurofibromatosis, von Hippel-Lindau disease, and Li-Fraumeni syndrome are all associated with a higher risk of brain tumors.

Signs and Symptoms

A brain tumor can cause symptoms by directly pressing on the surrounding brain, or by causing a buildup of spinal fluid and pressure throughout the brain (a condition known as hydrocephalus). A range of symptoms can develop as a result.

Signs or symptoms vary depending on a child's age and the location of the tumor, but may include:

• vomiting
• seizures
• weakness of the face, trunk, arms, or legs
• slurred speech
• difficulty standing or walking
• poor coordination
• headache
• in babies, a rapidly enlarging head

Because symptoms might develop gradually and can be like those of other common childhood conditions, brain tumors can be difficult to diagnose. So it's always wise to discuss any symptoms that concern you with your child's doctor.

Diagnosis

A doctor who suspects that a child has a brain tumor will order imaging studies of the brain: a CT scan, MRI, or possibly both. These procedures let doctors see inside the brain and identify any areas that look abnormal. Although both are painless, they do require children to be very still. Some kids, especially those who are young, may need to be sedated for these scans.

If imaging studies reveal a brain tumor, then surgery is likely to be the next step. A pediatric neurosurgeon will try to remove the tumor; if complete removal is not possible, then partial removal — or at least a biopsy (removal of a sample for microscopic examination) — may be done to confirm the diagnosis.

A pediatric pathologist (a doctor who helps diagnose diseases in children by looking at body tissues and cells under a microscope) will then review the tissue to classify and grade the tumor.

Special tests might be used to analyze the genetic makeup of the tumor cells. Using these tests to get specific information about cancer cells can help doctors identify the tumor and develop the best treatment plan for someone with a brain tumor.

Treatment

Treatment for a brain tumor requires a team of medical specialists. Most pediatric brain tumor patients require some combination of surgery, radiation therapy, and chemotherapy. Advancements in all three treatment areas in the last few decades have contributed to better outcomes.

The care of a child with a brain tumor is very complicated and requires close coordination between members of the medical team, which typically will include:

• a pediatric neuro-oncologist (a doctor who specializes in treating cancers of the brain or spine)
• a pediatric neurologist (a doctor who specializes in disorders of the nervous system)
• a pediatric neurosurgeon (a surgeon who operates on the brain or spine)
• a pediatric radiation therapist (a specialist who administers radiation therapy)
• pediatric rehabilitation medicine specialists, including speech, physical, and occupational therapists
• pediatric psychologists and social workers

These experts will choose a child's therapy very carefully. Finding a treatment that will be effective and cure the child but not cause unacceptable side effects is probably one of the most difficult aspects of treating brain tumors.

Surgery

Pediatric neurosurgeons are having more success than ever in helping to cure children with brain tumors, partly because of new technologies in the operating room and partly because it has been learned that an aggressive surgical approach at diagnosis can significantly increase the chance for cure.

Neurosurgeons may use stereotactic devices, which help target tumors by providing 3D images of the brain during surgery. Staged surgeries are also being used more frequently. This means that instead of trying to remove a large tumor all at once, surgeons will take out only part of the tumor at diagnosis. The patient will then get chemotherapy and/or radiation therapy to shrink the tumor and then return to the operating room a second or even a third time to try to remove the rest of the tumor.

After surgery, some patients may not require any more treatment beyond observation (periodic checkups and imaging scans to watch for problems). Many, however, will require radiation therapy, chemotherapy, or a combination of both.

Radiation Therapy

Radiation therapy — the use of high-energy light to kill rapidly multiplying cells — is very effective in the treatment of many pediatric brain tumors. However, because the developing brain in children younger than 10 years old (and especially those younger than 5) is highly sensitive to its effects, radiation therapy can have serious long-term consequences. These may include seizures, stroke, developmental delays, learning problems, growth problems, and hormone problems.

The decision to use radiation therapy is, therefore, an especially challenging one regarding young children.

The methods for giving radiation therapy have changed significantly over the last several decades. New computer-assisted technologies allow doctors to construct 3D radiation fields that accurately target tumor tissue while avoiding injury to important brain structures like the hearing centers.

Chemotherapy

Chemotherapy (chemo) is the use of drugs to kill cancer cells. It is often given through a special long-lasting intravenous (IV) catheter called a central line, and may require frequent hospital stays.

Although chemotherapy has many short-term side effects (such as fatigue, nausea, vomiting, and hair loss), it has fewer long-term side effects than radiation therapy. Many children with brain tumors are treated with chemo in order to delay or avoid radiation treatment.

Unlike brain tumors in adults, many pediatric brain tumors are highly sensitive to the effects of chemo, so it is routinely used for many kids with brain tumors.

Common Types of Brain Tumors

There are many different types of pediatric brain tumors, ranging from those that can be cured with minimal therapy to those that cannot be cured even with aggressive therapy.

Some of the most common types are:

Astrocytomas

Astrocytomas come in four major subtypes: juvenile pilocytic astrocytoma, fibrillary astrocytoma, anaplastic astrocytoma, and glioblastoma multiforme.

An important feature in determining the outlook for patients with astrocytomas is location, because this directly affects the chance for a cure. Tumors that can be completely removed surgically are much more likely to be cured, while those that can't be completely removed are, in general, less curable.

Ependymomas

Ependymomas are treated primarily with surgery and radiation therapy. If the tumor can be completely removed, patients with ependymomas may need no additional treatments. However, some completely removed ependymomas and most incompletely removed ependymomas will require further treatment — usually radiation therapy and sometimes also chemotherapy.

Brainstem Gliomas

Brainstem gliomas refer to a group of tumors of the brainstem that differ primarily by location. Most are curable with surgery and/or radiation therapy except the most common and serious type, the diffuse pontine glioma. These tumors, which originate in a part of the brainstem called the pons, are rarely curable even with aggressive therapy. Treatment for diffuse pontine gliomas usually includes radiation therapy, which lengthens survival and improves quality of life, but is rarely curative.

Medulloblastomas and Primitive Neuroectodermal Tumors (PNETs)

Medulloblastomas and primitive neuroectodermal tumors are very similar brain cancers and appear almost identical under the microscope. Medulloblastomas, by definition, can only occur in the posterior fossa or cerebellum (back part of the brain), while primitive neuroectodermal tumors can occur anywhere in the brain or spinal cord. These cancers are highly sensitive to chemotherapy and radiation therapy, so modern treatment regimens are usually curative. Although treatment regimens are effective, late side effects of therapy can be a significant problem.

Craniopharyngiomas

Craniopharyngiomas are low-grade tumors that arise in the middle of the brain near the pituitary gland. As a result of their location, many patients have endocrinologic (hormone) problems when the tumor is diagnosed and after it is treated.

While craniopharyngiomas can be cured with surgery alone, most pediatric centers do not attempt total removal of the tumor at diagnosis unless it can be accomplished without injury to the sensitive surrounding structures. Total removal of the tumor without consideration of these surrounding structures can cause permanent hormone deficiencies that can be difficult to manage.

Therefore, for most patients, only partial removal of the tumor is done at diagnosis, followed by radiation therapy for any remaining tumor. This approach usually results in effective treatment of the tumor without causing lifelong hormone deficiencies.

Germ Cell Tumors

These brain tumors usually arise from two special areas in the middle of the brain — the areas around the pituitary and pineal glands. Germ cell tumors include two main types, germinomas and nongerminomatous germ cell tumors.

Germinomas are sensitive to chemo and radiation therapy and both are usually used to help achieve an excellent cure rate. Nongerminomatous germ cell tumors include several different types of tumors which, in general, are not as curable as germinomas. Nongerminomatous germ cell tumors are treated with surgery, chemotherapy, and radiation therapy.

Late Effects

Late effects are problems that patients can develop after cancer treatments have ended. For survivors of pediatric brain tumors, late effects may include cognitive delay (problems with learning and thinking), seizures, growth abnormalities, hormone deficiencies, vision and hearing problems, and the possibility of developing a second cancer, including a second brain tumor.

Because these problems sometimes don't become apparent until years after treatment, careful observation and medical follow-up are needed to watch for these.

In some cases, short-term effects might improve with the help of physical, occupational, or speech therapy and may continue to improve as the brain heals.

In other cases, kids may experience side effects that are longer term, including learning disabilities; medical problems such as diabetes, growth delay, or delayed or early puberty; physical disabilities related to movement, speech, or swallowing; and emotional problems linked to the stresses of diagnosis and treatment. Some of these problems may become more severe with the passage of time.

Be aware of the potential for physical and psychological late effects, especially when the time comes for your child to return to school, activities, and friendships. Talk to teachers about the impact treatment has had on your child and discuss any necessary accommodations, including a limited schedule, additional rest time or bathroom visits, modifications in homework, testing or recess activities, and medication scheduling. Your doctor can offer advice on how to make the transition easier.

Caring for Your Child

Parents often struggle with how much to tell a child who is diagnosed with a brain tumor. Though there's no one-size-fits-all answer for this, experts do agree that it's best to be honest — but to tailor the details to your child's degree of understanding and emotional maturity.

Give as much information as your child requires, but not more. And when explaining treatment, try to break it down into steps. Addressing each part as it comes — visiting various doctors, having a special machine take pictures of the brain, needing an operation — can make the big picture less overwhelming. The members of the brain tumor care team are experts at helping families talk with the child and siblings if a family needs help with this.

Kids should be reassured that the brain tumor is not the result of anything they did, and that it's OK to be angry or sad. Really listen to your child's fears, and when you feel alone, seek support. Your hospital's social workers can put you in touch with other families of children with brain tumors who've been there and may have insights to share.

Also be aware that it's common for siblings to feel neglected, jealous, and angry when a child is seriously ill. Explain as much as they can understand, and enlist family members, teachers, and friends to help keep some sense of normalcy for them.

And finally, as hard as it may be, try to take care of yourself. Parents who get the support they need are better able to support their child.

Reviewed by: Andrew W. Walter, MD
Date reviewed: September 2010