Most people have never heard of neuroblastoma, a rare type of cancer that almost always occurs in infants and young children. It’s actually the most common type of cancer in infants, but it’s still rare enough that many doctors have never cared for a child with neuroblastoma.
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 diagnosed in infancy, the chance of recovery is good.
Neuroblastoma is a rare disease in which 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 and mature into functioning nerve cells. But in neuroblastoma, they become cancer cells instead.
Neuroblastoma most commonly starts in the tissue of the adrenal glands, the triangular glands on top of the kidneys that produce hormones responsible for controlling 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 (familial type), but most cases of neuroblastoma (98%) aren’t inherited (sporadic type). It occurs 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, with the majority of new cases occurring among those younger than 1 year old. Only about 700 new cases of neuroblastoma are diagnosed each year in the United States.
Neuroblastoma occurs when neuroblasts grow and divide uncontrollably instead of developing into nerve cells. The exact cause of this abnormal growth is unknown, but scientists believe it’s related to a defect in the genes of a neuroblast that allows it to divide uncontrollably.
Signs and Symptoms
The effects of neuroblastoma can vary widely depending on where the disease first started and how much it has spread to other parts of the body. The first symptoms are often vague and may include irritability, fatigue, loss of appetite, and fever. But because these early warning signs can develop gradually and mimic those 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 are caused by the tumor pressing on nearby tissues as it grows or by the cancer spreading to other areas. These signs vary depending on how much the cancer has grown and where it has spread.
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)
- 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)
If a doctor suspects neuroblastoma, your child may undergo a variety of tests to confirm the diagnosis and rule out other causes of symptoms. These tests may include simple urine 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 determine the location and size of the original (primary) tumor and determine whether it has spread to other areas of the body, a process called staging. Additional tests, such as bone marrow aspiration and biopsy, also may be performed.
The doctor also might order a MIBG scintiscan. In this imaging test, MIBG (iodine-131-meta-iodobenzyl-guanidine, a type of radioactive material) is injected into the blood and attaches to neuroblastoma cells. This allows the doctor to see whether the neuroblastoma has spread to other parts of the body. MIBG is also used at higher doses to treat neuroblastoma and may be used for scanning after treatment to determine if any cancer cells remain.
In rare cases, neuroblastoma may be detected by ultrasound before birth.
Most cases of neuroblastoma require treatment. The type will depend on several factors — including the child’s age, the characteristics of the tumor, and whether the cancer has spread — that determine risk.
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, about one-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 the primary treatments and may be performed in conjunction with radiation therapy and stem cell or bone marrow transplantation.
Another treatment the doctor might suggest is retinoid therapy. Scientists believe that retinoids (a class of substances chemically related to vitamin A) 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.
Newer treatment options include tumor vaccines and immunotherapy using monoclonal antibodies, special substances that can be injected into the body to seek out and attach to cancer cells. They’re sometimes used to deliver drugs or other treatments directly to cancer cells, helping to improve treatment.
With treatment, many children with neuroblastoma have a good chance of surviving. In general, neuroblastoma has a more favorable outcome if the cancer hasn’t spread or if the child is younger than 1 year old when it’s 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. Some late effects of neuroblastoma include growth and developmental delays and loss of function in involved organs.
Children treated for neuroblastoma may also be at higher risk for other cancers.
The risk of developing these late effects depends on various factors, such as the specific treatments used and the child’s age during treatment.
Although rare, some kids with neuroblastoma develop opsoclonus-myoclonus syndrome, a condition in which their immune system attacks normal nerve tissue. As a result, some might experience learning disabilities, delays in muscle and movement development, language problems, and behavioral problems.