Neuro-oncology

Central nervous system (CNS) tumors are a collection of cells with abnormal growth located in the brain, and spinal cord. They are also known as neoplasms, growth, mass or lesions.

Collectively, brain and spinal cord tumors are the second most common type of childhood cancer, after leukemia. Tumors in the are classified as either PRIMARY or SECONDARY. They can be either BENIGN or MALIGNANT

The month of May is Brain Tumor Awareness Month, a time to raise awareness about brain tumors and educate the community.

Can children get brain cancer?

Yes. More than 30,000 cases of brain tumors were diagnosed in children aged 1 - 19 years old and more than a half of them will die due to complications of this condition.

Are all brain cancers alike?

No. There are actually more than 100 kinds of brain tumors. The most common types seen in children are the following:

- Astrocytoma

- Ependymoma

- Germ cell tumors

- Glioblastoma

- Medulloblastoma

Brain cancers are also different depending on the part of the brain that is involved.

What about spinal cord tumors?

The spinal cord is the part of the CNS that connects the brain to the rest of the body. Tumors in this area occurs less frequently than those in the brain, but can be just as devastating.

When should I suspect a brain or spine tumor in my child?

Symptoms of brain and spine tumor are dependent on their location, as well as the size and rate of growth. The most common symptoms seen in children with a brain tumor are the following:

-- Headaches that become more severe and last longer than usual

-- Nausea, vomiting and increasing lethargy (becoming more drowsy than usual)

-- New-onset seizure

-- Changes in vision, squinting , eye movement problems

-- Weakness in one side or half of the body

-- Behavioral or personality changes

In young infants and smaller children, they may have increasing irritability and/or enlarging head size, more than expected for age.

Spine tumors can present as back pain, gradually decreasing sensation or weakness, and incontinence.

What caused my child's tumor?

The cause is not known in most of the pediatric brain and spine tumors. But like other tumors, these are usually caused by changes (mutations) in the DNA inside cells. In healthy and normal cells, the DNA provides a set time for these cells to die. Tumor cells on the other hand, do not undergo this natural process of cell death. They continue to grow and multiply, causing the tumor's growth.

What we know is that certain genes that help cells grow, divide, and stay alive, called oncogenes become abnormally active; whereas genes that help keep cell division under control, or cause cells to die at the right time, called tumor suppressor genes become inactive. The gene mutations that cause this can be inherited from a parent, but more often they occur during a person’s lifetime due to acquired causes that damage the DNA.

What are the risks of developing this?

A genetic background or family history of CNS tumors can be present expecially in those with inherited tumor syndromes such as neurofibromatosis, tuberous sclerosis, Li-Fraumeni syndrome, and von Hippel-Lindau disease.

Chemical, physical or biological neurocarcinogens are being studied as possible links to developing CNS tumors.

Other than radiation, there are no known lifestyle-related or environmental factor that is clearly linked to childhood CNS tumors and most will develop in people who do not have any risk factors.

Individuals with weakened immune systems have been found to have a higher risk of CNS lymphoma.

Biopsy plays an important part in diagnosing a tumor. A biopsy is a procedure where tissue sample with abnormal cells are taken and and sent for testing in a laboratory. In children with CNS tumors, this is usually done during surgery to remove the tumor. If surgery is not possible, a needle is inserted in the area of the tumor through a small hole to obtain the sample. A neurosurgeon does these procedures. The sample is then sent to the laboratory where the tumor's type and grade are determined by a pathologist.

Molecular and genetic testing are recommended in many cases of CNS tumors. Current information and ongoing researches on the molecular signature and genetic risk of these cancer cells help identify targeted therapy for more precise treatment protocols and clinical trials.

How can we know if there really is a brain tumor?

If your child is exhibiting signs likely caused by a brain or spine tumor, your health care provider will ask for a neuro-imaging scan of the area affected. This may be in the form of a Magnetic Resonane Imaging (MRI) or Computed Tomography (CT) scan. In some cases, a cranial Ultrasound or Positron Emission Tomography (PET) scan

may also be used.

PET scan image of brain scan more detailed.jpg

Blood tests for tumor markers like LDH, beta-HCG and AFP may also be requested to help differentiate one type of tumor from another.

Additional screening tests for other complications or entities associated with the tumor are also common. These will depend on the area involved and may include but are not limited to the following: various hormone functions, visual and hearing tests, and electrophysiologic tests.

How are CNS tumors treated?

In cases when a tumor is accessible, surgery to remove tumor cells remain the initial step and primary treatment option. However, this is not always possible when the tumor is located in areas that are hard to reach, or upon removal, could cause significant damage to vital functions. The goal of surgery is to excise the as much tumor as safely as possible and to provide samples for histologic diagnosis.

Chemotherapy is the use of strong medicines to kill the tumor cells. These compounds destroy cancer cells and disturbs their growth and is generally employed in faster growing tumors.

Because our nervous system is protected by blood-brain barrier, it may be more difficult for some substances (such as anticancer drugs) to enter the brain. This network of blood vessels and cells that filters blood flowing to the brain and spinal cord prevents many chemotherapy drugs from reaching the tumor cells in adequate amounts to destroy them.

Chemotherapy medications must be able to cross the blood-brain barrier and depending on the drug, can be administered in a variety of ways:

- as a drip into your bloodstream (intravenously)

- into your spine (intrathecal chemotherapy)

- directly into your brain (for example, chemotherapy wafers)

- as tablets or capsules that you swallow (oral chemotherapy)

Radiation therapy uses high-energy radioactive rays or proton particles to destroy brain and spinal cord tumors. This is usually given in repeated doses to kill cancer cells or keep them from multiplying. The stronger the radiation, the deeper it can penetrate. Healthy cells are often damaged by radiation therapy, but depending on the tumor type and location, a person may be able to receive a modified form of therapy to lessen damage to healthy cells and improve the overall treatment.

Stereotactic radiosurgery may be used for surgically inaccessible tumors. This isn’t a type of brain surgery but by using a highly accurate positioning systems and 3D imaging, multiple, sharply focused radiation beams can target the brain or spinal cord tumor from multiple angles. This may also be used at the end of conventional radiation treatment.

Immunotherapy or Biological therapy uses the patient's own immune system to recognize and fight cancer cells. The immune system is designed to attack foreign substances in the body, but because cancer cells aren't foreign, they usually escaped detection and do not generate an immune response. To enhance the body's immune system, different methods to provoke a strong immune response to tumor cells may be used such as:

- Proteins (interleukin and interferon) that slow tumor growth

- Antibodies that are linked to immuno-toxin drugs that seek out tumor cells and deliver their toxin, with minimal damage to surrounding normal cells

- Gene therapy employs inactive viruses that can pass through the brain's protective blood-brain barrier to deliver a suicide gene to the tumor cell

- Vaccine therapy attempt to target multiple antigens which the tumor may express.

Targeted therapy or Molecular targeted therapy uses drugs that target specific molecules (such as proteins) on or inside the cancer cells. The abnormal cancer cells have molecules help send signals that tell cells to grow or divide. By targeting these molecules, the drugs stop the growth and spread of cancer cells and limit harm to normal cells. Only specific types of brain tumors with identified molecular markers can respond to this treatment.

Multidisciplinary care is important in managing CNS tumors. Beyond the diagnosis and treatment, long term follow up care and rehabilitation is needed to optimize a patient's quality of life.

A specialized team of doctors advises and assists individuals throughout treatment and rehabilitation and may include 2 or more of the following:

A neurologist / pediatric neurologist is a doctor who specializes in CNS disorders.
A neuro-oncologist is a neurologist or oncologist who specializes in CNS tumors.
An oncologist is a doctor who specializes in cancer
A neuro-radiologist is a doctor who specializes in the CNS and is trained in reading diagnostic imaging results.
A pathologist is a clinical doctor who diagnoses diseases of tissues or cells using a variety of laboratory tests.
A neurosurgeon is a brain or spinal cord surgeon. Specialized training in removal of central nervous system tumors may have been completed.
A radiation oncologist is a doctor who specializes in using radiation to treat cancer.

Rehabilitation doctors and allied services including physical,occupational and speech therapy are relied on especially to assist recovery and functionality following disabilities associated with the tumor and its treatment.

Palliative care specialists are those experienced in the medical care for people living with a serious illness like a brain tumor as well as addressing the needs of their families. The goal is to provide support and relief from the symptoms and stress that a serious illness can cause. Emotional and psychological support are just as important as well as continuing educational support and counseling to help improve the quality of life.