Neuroblastoma is a rare cancer, with about 800 new cases in the United States each year. However, it is the most common cancer in infants and accounts for 6% of all childhood cancers. Most cases occur in children under 2 years of age and 90% of cases are in children under 5. Neuroblastoma in children older than 10 years or in adults is very rare.
Neuroblastoma affects immature nerve cells called neuroblasts that are present in unborn, developing babies. Normally, neuroblasts mature into nerve cells by birth or shortly thereafter. Neuroblastoma affects these early cells in the sympathetic nervous system. Instead of growing into nerve cells, they form tumors.
The sympathetic nervous system is part of the autonomic nervous system—the system that controls involuntary functions, such as heart rate and digestion. There are several components of the sympathetic nervous system. This includes fibers that run on either side of the spinal cord, clusters of nerve cells called ganglia, and nerve-like cells in the adrenal gland. The adrenal glands sit on top of the kidneys and release hormones, such as adrenaline. Adrenaline helps control blood pressure and stress reactions.
Most neuroblastomas develop in the adrenal glands. The rest occur in ganglia in the abdomen, pelvis, chest or neck, or along the spine. About 98% of cases occur from random gene mutations that are not inherited. This is sporadic type neuroblastoma. The remaining cases of neuroblastoma are familial type, meaning it is passed from parent to child.
Neuroblastoma symptoms depend on where the tumor develops. In the most common form, symptoms may include belly pain, loss of appetite, and changes in bowel habits. These symptoms tend to develop slowly and can mimic other more common childhood illnesses. This can make it challenging for doctors to make a neuroblastoma diagnosis. More concerning symptoms include a mass you can feel, a swollen belly, and bone pain.
There are different neuroblastoma stages and risk levels, which help guide treatment. Some neuroblastomas in very young children end up going away on their own. And some mature into normal cells and become a benign tumor. So, watchful waiting may be an option in low-risk cases. However, more than half of the cases are high risk. Typical neuroblastoma treatment includes surgery, chemotherapy, and radiation therapy.
Make an appointment to see your child’s doctor if you notice symptoms or behavior changes that concern you.
Neuroblastoma symptoms depend on the location of the tumor. It may be possible to feel a mass where the tumor is, such as in the belly or neck. Children may also experience vague symptoms, such as fever, tiredness, easy bruising or bleeding, bone pain, and irritability.
Common symptoms of neuroblastoma in the abdomen or pelvis
In the abdomen or pelvis, common neuroblastoma symptoms include:
- Appetite loss
- Changes in bladder or bowel habits
- Feeling of fullness
- Swollen abdomen or swelling in the legs or in a boy’s scrotum
Common symptoms of neuroblastoma in the chest or neck
In the chest or neck area, common neuroblastoma symptoms include:
- Bulging or bruising around the eyes
- Drooping eyelid or small pupil size
- Problems feeling or moving body parts (from a tumor pressing on the spinal cord)
- Swelling in the face, neck or arms
- Wheezing or trouble breathing or swallowing
There are more common causes for many of these symptoms in children. If your child has symptoms or complaints that concern you, see your pediatrician promptly.
Cancers start when normal cell growth goes haywire. The cancerous cells grow unchecked and crowd out any normal cells. This happens when changes, or mutations, occur in genes that normally regulate cell growth. In a small percent of neuroblastoma cases, the genetic mutations are inherited from a parent. This is familial neuroblastoma. The rest—about 98%—happen spontaneously, very early in embryonic development. This is called sporadic neuroblastoma. It’s not clear what causes this type of mutation.
Neuroblastoma most often affects children under 5 years of age. About 2% of children with neuroblastoma have an increased risk due to their family history. Having birth defects may increase the risk of neuroblastoma. There are no other known risk factors for the disease. The fact is that neuroblastoma-causing mutations can be acquired by chance—due to errors (or ‘mistakes’) when cells grow and divide during embryonic development. Most of the mistakes do not lead to cancer, but sometimes the mistakes create more drastic changes that can trigger cancerous growth.
Unlike adult cancers, lifestyle factors do not play much of a role in childhood cancers, including neuroblastoma.
Reducing your risk of neuroblastoma
Reducing the risk of cancer usually relies on changing lifestyle habits. However, there are no modifiable risk factors for neuroblastoma. Regular prenatal care can help ensure your developing baby gets optimal nutrition for proper development. And regular pediatric care offers the best chance of catching potential problems early.
If you have a family history of neuroblastoma, consider working with a genetic counselor to understand the risk to your children.
Neuroblastoma treatment depends on several factors that determine the cancer’s risk category. Doctors classify neuroblastoma as low, intermediate or high risk. The stage of the tumor plays a role in its risk category. Staging is the process of determining if the cancer has spread and how extensive it is. Generally, the lower the stage, the better the prognosis. Other factors that go into risk categorization include age and characteristics of the tumor, such as its MYCN gene status. Neuroblastoma diagnosis includes determining the tumor’s genetic characteristics.
Low-risk tumors may or may not require treatment. Some of these neuroblastomas will go away on their own or mature into benign tumors. This is more likely to happen in very young children, usually younger than six months of age. For this age group, doctors may recommend watchful waiting to see if the tumor disappears or continues to grow.
Low-risk tumors that grow or cause symptoms, and intermediate- and high-risk tumors require treatment. Typical treatment includes surgery to remove the tumor, or as much of it as possible.
Intermediate-risk tumors usually require chemotherapy before or after surgery.
High-risk tumors need more aggressive three-phase treatment:
- Induction with chemotherapy to destroy as much of the cancer as possible. Surgery after chemotherapy can remove any remaining tumor.
- Consolidation to kill any remaining cancer cells. This consists of high-dose chemotherapy followed by two stem cell transplants and immunotherapy. After the stem cell transplants, treatment often includes radiation to the original tumor site.
- Maintenance with retinoid therapy and immunotherapy to try to keep the cancer from returning
Possible complications of neuroblastoma include spinal cord compression, paraneoplastic syndrome, and cancer spread—or metastasis. Spinal cord compression occurs when the tumor presses on the spinal cord. This can result in pain and paralysis. Paraneoplastic syndrome occurs when chemicals the tumor secretes cause problems in other tissues, such as the muscles or intestines. Symptoms can include coordination problems, abnormal eye movements, and diarrhea.
Some neuroblastomas grow and spread quickly. Others grow more slowly and are less likely to spread. In general, the prognosis is better when the cancer has not spread. It is also better for younger children, especially when children are under 1 year of age at diagnosis. Unfortunately, 2 out 3 children have disease that has already spread at diagnosis.
For low- and intermediate-risk tumors, the 5-year survival rate is very high at greater than 95% and 90 to95%, respectively. The rate drops to 40 to 50% for high-risk tumors. Your child’s doctor is the best resource for understanding how survival rates apply to your child and your child’s outlook for the future.