Neuroblastoma

Neuroblastoma is a rare cancer that starts in early nerve cells (neuroblasts), usually in infants and young children. It often begins in the adrenal glands but can appear anywhere along the sympathetic nervous system, such as the chest, neck, or abdomen. Symptoms vary widely depending on the tumor's location and whether it has spread.

What is Neuroblastoma?

Neuroblastoma is a type of cancer that develops from immature nerve cells, called neuroblasts, typically affecting infants and young children. It most commonly starts in the adrenal glands, located above the kidneys, but can also form in nerve tissue in the chest, neck, pelvis, or spine.

Neuroblasts are early nerve cells that are part of the sympathetic nervous system. This system controls involuntary body functions like heart rate and blood pressure. Normally, neuroblasts mature into functioning nerve cells. In neuroblastoma, these cells fail to mature and instead grow uncontrollably, forming a tumor. Neuroblastoma is the most common cancer diagnosed in infants. While it can occur anywhere along the sympathetic nervous system, it frequently originates in the adrenal glands. These small glands sit on top of the kidneys and produce important hormones. Other common sites include nerve tissue in the abdomen, chest, neck, or near the spinal cord.

Symptoms

Neuroblastoma symptoms vary greatly depending on where the tumor is located and if it has spread. Common signs can include a swollen belly, bone pain, unexplained fever, or dark circles around the eyes, often appearing as a persistent lump or discomfort in a child.

The signs of neuroblastoma can be subtle and depend on the tumor's size and location. If the tumor is in the abdomen, you might notice a lump or swelling, along with constipation or changes in bowel habits. Tumors in the chest can cause breathing difficulties. If the cancer has spread to bones, a child might experience bone pain, limping, or refusal to walk. Spread to the area around the eyes can lead to dark circles, sometimes called "raccoon eyes," or bulging eyes. Other general symptoms can include unexplained fever, weight loss, fatigue, or irritability. Any persistent or unusual symptom in a child warrants a doctor's visit.

Causes & risk factors

The exact cause of neuroblastoma is not fully understood, but it begins when immature nerve cells (neuroblasts) develop genetic changes that cause them to grow uncontrollably. Most cases are not inherited, meaning they don't run in families, and there are no known lifestyle or environmental risk factors.

Neuroblastoma starts with mutations, or changes, in the DNA of neuroblasts. These genetic changes tell the cells to keep growing and dividing instead of maturing into healthy nerve cells. In most children with neuroblastoma, these genetic mutations happen randomly after birth and are not passed down from parents. A small number of cases are linked to inherited genetic changes, such as those in the ALK gene. In these rare instances, the tendency to develop neuroblastoma can run in families. However, for the vast majority of children, there are no known risk factors like diet, lifestyle, or exposure to certain substances that increase the chance of developing this cancer.

How it's diagnosed

Diagnosing neuroblastoma typically involves a combination of physical exams, imaging tests like MRI or CT scans to locate tumors, and urine tests to check for specific hormone levels. A biopsy, which involves taking a tissue sample for examination, is usually needed to confirm the diagnosis.

A doctor will start with a physical exam, looking for lumps or other signs. Urine tests are often performed to check for high levels of certain substances called catecholamines, such as vanillylmandelic acid (VMA) and homovanillic acid (HVA). These are breakdown products of hormones often produced by neuroblastoma cells. Imaging tests help locate the tumor and see if it has spread. These can include X-rays, ultrasound, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, and specialized nuclear medicine scans like MIBG scans or PET scans. Finally, a biopsy is crucial. This involves removing a small piece of the tumor or bone marrow to be examined under a microscope, confirming the presence of cancer cells and helping determine the specific type of neuroblastoma.

Treatment options

Treatment for neuroblastoma depends on the child's age, the tumor's stage, and its specific characteristics. Options can include surgery to remove the tumor, chemotherapy to kill cancer cells, radiation therapy, stem cell transplants, immunotherapy, and targeted therapy, often used in combination.

Treatment plans are tailored to each child, based on their risk group (low, intermediate, or high). For low-risk neuroblastoma, observation or surgery alone may be sufficient. Some low-risk tumors can even shrink or disappear on their own without treatment. Intermediate and high-risk cases often require more intensive treatment. Surgery is frequently used to remove as much of the tumor as possible. Chemotherapy, which uses powerful drugs to kill cancer cells, is a common treatment. Radiation therapy uses high-energy beams to destroy cancer cells or shrink tumors. For high-risk neuroblastoma, a stem cell transplant might be used after high-dose chemotherapy to restore healthy blood-forming cells. Immunotherapy, which helps the body's immune system fight cancer, and targeted therapy, which focuses on specific vulnerabilities in cancer cells, are also important options, especially for high-risk disease. These treatments are often used together to improve outcomes.

Recovery & outlook

The recovery and outlook for neuroblastoma vary significantly, largely depending on the child's age at diagnosis, the tumor's stage, and its biological features. Low-risk neuroblastoma often has a good prognosis, sometimes resolving on its own, while high-risk forms are more challenging to treat.

The prognosis for neuroblastoma is highly variable. Children diagnosed as infants, especially those with low-risk disease, generally have a better outlook. In some low-risk cases, the tumor may even shrink or disappear without any treatment, a process called spontaneous regression. However, high-risk neuroblastoma is an aggressive form of the disease that is more difficult to treat and has a higher chance of returning. Even with intensive treatments, the outlook for high-risk cases can be challenging. Long-term follow-up care is essential for all children treated for neuroblastoma to monitor for recurrence and manage any potential side effects from treatment.

When to see a doctor

You should see a doctor if your child develops any unusual or persistent symptoms that concern you, such as a new lump, unexplained pain, changes in bowel habits, or sudden fatigue. While these symptoms can have many causes, a medical evaluation is important for an accurate diagnosis.

It's important to remember that many common childhood illnesses can cause symptoms similar to neuroblastoma. However, if your child has any new, persistent, or worsening symptoms, especially those listed below, it's best to consult a healthcare professional promptly. Specific signs that warrant medical attention include a noticeable lump in the abdomen, neck, or chest, unexplained bone pain or limping, dark circles around the eyes, or bulging eyes. Also, seek medical advice for persistent fever without a clear cause, unexplained weight loss, changes in bowel or bladder habits, or sudden weakness or paralysis. Early diagnosis can be crucial for effective treatment.

Frequently asked questions

Is neuroblastoma hereditary?

Most cases of neuroblastoma are not hereditary. They result from random genetic changes that occur after birth. Only a small percentage are linked to inherited genetic mutations, such as those in the ALK gene, which can run in families.

Can neuroblastoma go away on its own?

Yes, in some cases, particularly low-risk neuroblastoma diagnosed in infants, the tumor can spontaneously shrink or disappear without treatment. This is known as spontaneous regression. However, not all neuroblastomas behave this way, and medical evaluation is always necessary.

What is the difference between neuroblastoma and other childhood cancers?

Neuroblastoma specifically develops from immature nerve cells (neuroblasts) of the sympathetic nervous system, often in the adrenal glands. Other childhood cancers originate from different cell types and locations, such as leukemia (blood cells) or Wilms' tumor (kidney cells), each with distinct characteristics and treatments.

How common is neuroblastoma?

Neuroblastoma is considered a rare cancer, but it is the most common cancer diagnosed in infants. It accounts for about 6% of all childhood cancers. While rare, it is the most common solid tumor outside the brain in children.

What are the long-term effects of neuroblastoma treatment?

Long-term effects depend on the specific treatments used, their intensity, and the child's age. They can include issues with growth and development, fertility problems, heart or kidney damage, hearing loss, or an increased risk of secondary cancers. Regular follow-up care helps manage these potential effects.

Are there different types or stages of neuroblastoma?

Yes, neuroblastoma is categorized into different stages and risk groups (low, intermediate, high) based on factors like the child's age, tumor size and location, spread of the cancer, and specific genetic features of the tumor cells. These classifications guide treatment decisions and predict outlook.

Sources

• MedlinePlus — Neuroblastoma
• Mayo Clinic — Neuroblastoma
• Cochrane Library — Neuroblastoma