Most people have never heard of neuroblastoma, but it's actually the most common type of cancer in infants.
In this rare disease, a solid tumor (a lump or mass caused by uncontrolled or abnormal cell growth) is formed by special nerve cells called neuroblasts. Normally, these immature cells grow into functioning nerve cells. But in neuroblastoma, they become cancer cells instead.
Although neuroblastoma sometimes forms before a child is born, it usually isn't found until later, when the tumor begins to grow and affect the body. When neuroblastoma is found and treated in infancy, the chance of recovery is good.
Neuroblastoma most commonly starts in the tissue of the adrenal glands, the triangular glands on top of the kidneys that make hormones that control heart rate, blood pressure, and other important functions. Like other cancers, neuroblastoma can spread (metastasize) to other parts of the body, such as the lymph nodes, skin, liver, and bones.
In a few cases, the tendency to get this type of cancer can be passed down from a parent to a child (called the familial type). But most cases of neuroblastoma (98%) are not inherited (called the sporadic type). It happens almost exclusively in infants and children, and is slightly more common in boys than in girls.
Children diagnosed with neuroblastoma are usually younger than 5 years old, and most new cases happen in children younger than 2. About 700 new cases of neuroblastoma are diagnosed each year in the United States.
Neuroblastoma happens when neuroblasts grow and divide out of control instead of developing into nerve cells. The exact cause of this abnormal growth is not known, but scientists believe a defect in the genes of a neuroblast allows it to divide uncontrollably.
Signs and Symptoms
The effects of neuroblastoma can be different depending on where the disease first started, how much the cancer has grown, and how much it has spread to other parts of the body.
The first symptoms are often vague and may include irritability, being very tired, loss of appetite, and fever. But because these early signs can develop slowly and be similar to symptoms of other common childhood illnesses, neuroblastoma can be difficult to diagnose.
In young children, neuroblastoma often is discovered when a parent or doctor feels an unusual lump or mass somewhere in the child's body — most often in the abdomen, though tumors also can appear in the neck, chest, and elsewhere.
The most common signs of neuroblastoma happen when the growing tumor presses on nearby tissues or when the cancer spreads to other areas. For example, a child may have:
- a swollen stomach, abdominal pain, and decreased appetite (if the tumor is in the abdomen)
- bone pain or soreness, black eyes, bruises, and pale skin (if the cancer has spread to the bones or bone marrow)
- weakness, numbness, inability to move a body part, or difficulty walking (if the cancer presses on the spinal cord)
- drooping eyelid, unequal pupils, sweating, and red skin, which are signs of nerve damage in the neck known as Horner's syndrome (if the tumor is in the neck)
- difficulty breathing (if the cancer is in the chest)
- fever and irritability
If a doctor suspects neuroblastoma, your child may undergo tests to confirm the diagnosis and rule out other causes of symptoms. These tests may include simple urine tests and blood tests, imaging studies (such as X-rays, a CT scan, an MRI, an ultrasound, and a bone scan), and a biopsy (removal and examination of a tissue sample).
These tests help to find the location and size of the original (primary) tumor and see whether it has spread to other areas of the body, a process called staging. Other tests, such as a bone marrow aspiration and biopsy, also might be done.
The doctor might order an MIBG scan. In this imaging test, MIBG (iodine-meta-iodobenzyl-guanidine, a type of radioactive material) is injected into the blood and attaches to neuroblastoma cells. This lets the doctor see if the neuroblastoma has spread to other parts of the body. MIBG is also used at higher doses to treat neuroblastoma, and can be used for scanning after treatment to see if any cancer cells remain.
In rare cases, neuroblastoma may be detected by ultrasound before birth.
How neuroblastoma is treated depends on factors that determine risk, such as the child's age, the characteristics of the tumor, and whether the cancer has spread.
The three risk groups are: low risk, intermediate risk, and high risk. Children with low-risk or intermediate-risk neuroblastoma have a good chance of being cured. However, more than half of all children with neuroblastoma have the high-risk type, which can be difficult to cure.
Because some cases of neuroblastoma disappear on their own without treatment, doctors also sometimes use "watchful waiting" before trying other treatments.
Unfortunately, in most cases the neuroblastoma has spread by the time it's diagnosed. In these cases, chemotherapy and surgery are usually the primary treatments and may be done along with radiation therapy and stem cell transplants.
Another treatment the doctor might suggest is retinoid therapy. (Retinoids are substances that work in the body much like vitamin A.) Scientists believe that retinoids can help cure neuroblastoma by encouraging cancer cells to turn into mature nerve cells. Retinoids are often used after other treatments to help prevent the cancer from growing back.
Other treatment options include tumor vaccines and immunotherapy using monoclonal antibodies. Monoclonal antibodies are special substances that can be injected into the body to seek out and attach to cancer cells. They're sometimes used to stimulate the immune system to attack the neuroblastoma cancer cells.
With treatment, many children with neuroblastoma have a good chance of surviving. In general, neuroblastoma has a better outcome if the cancer hasn't spread or if the child is younger than 1 year old when diagnosed.
High-risk neuroblastoma is harder to cure and is more likely to become resistant to standard therapies or come back (recur) after initially successful treatment.
"Late effects" are problems that patients can develop after cancer treatments have ended. Late effects of neuroblastoma include growth and developmental delays and loss of function in involved organs. Hearing loss is common. The risk of developing late effects depends on things like the specific treatments used and the child's age during treatment.
Although rare, some kids with neuroblastoma develop opsoclonus-myoclonus syndrome, a condition where the immune system attacks normal nerve tissue. As a result, some might have learning disabilities, delays in muscle and movement development, language problems, and behavioral problems.
Children treated for neuroblastoma also may be at higher risk for other cancers.
Caring for Your Child
Being told your child has neuroblastoma can be overwhelming, and cancer treatment can take a huge toll on your child and family. At times, you might feel helpless.
But you play a vital role in your child's treatment. During this difficult time, it's important to learn as much as you can about neuroblastoma and its treatment. Being knowledgeable will help you make informed decisions and better help your child cope with the tests and treatments. Don't be afraid to ask the doctors questions.
Although you might feel like it at times, you're not alone. It can help to find a support group for parents whose kids are coping with cancer (there are groups specifically for parents of children with neuroblastoma).
Parents often struggle with how much to tell a child who's diagnosed with cancer. While there's no perfect answer, experts 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 needs, 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 body, needing an operation — can make the big picture less scary. Be sure to explain to your child that the disease is not the result of anything he or she did.
Also remember 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 involve 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 children.