Neuroblastomas
Neuroblastomas are rare cancers primarily affecting infants and young children under five years old, originating from primitive nerve cells in the sympathetic nervous system. Most commonly, these tumors arise in the adrenal glands or sympathetic ganglia in the abdomen, but they can also develop in the chest, neck, or pelvis. Although heredity is a known risk factor, it accounts for only a small percentage of cases. Symptoms can vary widely and may include fatigue, abdominal swelling, breathing difficulties, and bone pain. Diagnosis typically involves physical examinations, imaging tests, and cytogenetic analyses, as there is no standard screening process for neuroblastoma. Treatment is multifaceted, often involving surgery, chemotherapy, and radiation therapy, tailored based on the tumor's stage and risk classification. Prognosis is highly dependent on factors such as the child's age at diagnosis and the stage of the disease, with survival rates varying significantly between low, intermediate, and high-risk groups. While neuroblastomas cannot be prevented, early detection and comprehensive treatment can significantly impact outcomes.
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Subject Terms
Neuroblastomas
ALSO KNOWN AS: Childhood autonomic nervous system tumors
RELATED CONDITIONS: Ganglioneuroblastomas, ganglioneuromas, Horner’s syndrome,
DEFINITION: Neuroblastomas are rare cancers usually found in infants and young children under five. They grow from primitive, embryonic nerve cells in the nervous system. One-third of tumors begin in the adrenal glands and one-fourth in the sympathetic nervous system ganglia, with growth in the abdomen. The remainder of neuroblastomas grow in the chest, neck, or pelvis, but all evolve from sympathetic nervous system ganglia.
Risk factors:Heredity may play a role in some neuroblastomas and is the only known risk factor. Infants with the familial form of neuroblastoma usually have a parent or someone in the family who had a neuroblastoma as an infant, and familial cases are usually diagnosed at a younger age. When familial neuroblastoma develops, there may be two or more tumors in various organs. It is necessary to differentiate metastasis from multiorgan familial neuroblastoma.
Etiology and the disease process: There is no known cause of neuroblastoma other than heredity, which is involved in only 1 to 2 percent of cases. Neuroblastoma may form before birth and is occasionally found by fetal ultrasound. Most tumors develop before age five. Tumors are generally found only as the cancer grows and cause symptoms by pressing on organs. The tumor has usually metastasized by the time of diagnosis, and metastasis to the bone is common. Most tumors are fast-growing, but in rare cases, the tumor cells may die spontaneously (apoptosis) and disappear. Occasionally, the tumor cells may quit dividing and become normal ganglia. This causes the tumor to become a ganglioneuroma, which is benign.
Incidence: Neuroblastoma is rare, with around 650 diagnoses occurring annually in the United States, but it is the most common cancer in babies under seventeen months and the cause of 15 percent of pediatric deaths. Nearly all cases are diagnosed before age five, with the median age at diagnosis being seventeen months. Neuroblastoma may be slightly more common in boys than girls. Neuroblastoma accounts for 6 percent of cancers in children.
Symptoms: Common symptoms of neuroblastoma include fatigue; diarrhea; a swollen abdomen; difficulty breathing as the tumor gets larger or spreads to the chest area; dark circles under the eyes; pale or flushed, red skin; excessive sweating; bone pain or tenderness; rapid pulse; high blood pressure; poorly controlled movement of the extremities; or paralysis. Symptoms depend on the site of the tumor, and parents may notice or feel a mass in the abdomen, chest, or neck.
Screening and diagnosis: There is no screening test for neuroblastoma. If a family has a history of neuroblastoma, it is important to tell the pediatrician at the first visit. Parents should take note of any unusual lumps, swellings, or changes in bowel or bladder patterns, as the symptoms of neuroblastoma often manifest in this manner. The diagnosis of neuroblastoma begins with a careful physical examination, as masses may be palpated (felt) in the abdomen, chest, or neck. A twenty-four-hour urine test, blood work, and cytogenetic analysis to look for changes in chromosomes are done. A bone marrow or specimen may also undergo cytogenetic analysis and pathology review. Imaging tests may include ordinary X-rays, computed (CT) scans, ultrasound, a (MRI) scan, and a positron emission tomography (PET) scan.
Once a diagnosis is made, staging neuroblastoma is important to determine the treatment needed. The first step is to determine if the tumor has spread to other parts of the body. Additional tests may be indicated, including lymph node biopsy or fine needle aspiration of fluid from a lymph node as well as imaging studies with dye injection or injection of a small amount of radioactive tracer material.
To stage neuroblastomas, medical professionals use the International Neuroblastoma Staging System (INSS), based on surgical resection, or the International Neuroblastoma Risk Group Staging System (INRGSS), which relies on imaging results, called image-defined risk factors (IDRFs), to stage cancer before treatments begin. Bone marrow biopsy is often required to stage the condition properly. The higher the stage, the more extensive the disease and its spread. Neuroblastomas are categorized as low risk, intermediate risk, and high risk based on stage, with treatment determined by risk group.
Treatment and therapy: Treatment for neuroblastoma is multimodal, which means surgery, radiation therapy, chemotherapy, and, in rare instances, watchful waiting may be used. The higher the risk group, the more aggressive the therapy. Surgery is the initial treatment of choice to remove as much of the tumor as possible and to biopsy lymph nodes. Radiation therapy may be used, especially if part of the tumor has been left behind after surgery or if distant metastases exist. Chemotherapy is used to kill any cells remaining after surgery or to attack cells that may have spread elsewhere in the body. Patients may be watched carefully until a change in their condition indicates the therapy method. A team will make the best treatment decisions for the child based on staging, location of the tumor, and other factors.
Prognosis, prevention, and outcomes: The prognosis for neuroblastoma depends on the age of the child at diagnosis, the stage of the disease, the tumor site, the size of the tumor, and the type of tumor cells. Infants have better prognoses than older children. Low-risk group survival at five years is more than 95 percent, intermediate group survival is 90 to 95 percent, and high-risk group survival is approximately 50 percent. Up to 90 percent of babies in the low- or intermediate-risk groups fully recover, sometimes without treatment. Neuroblastoma cannot be prevented.
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