Solid cancer of the sympathetic nervous system tissue often located in the adrenal glands, and to a lesser extent in other locations. Despite being considered rare, it is the most common pediatric extracranial tumor, with an annual incidence of 7-24 cases per million children. The survival rate varies between 95-50% depending on tumor staging.
Neuroblastomas can occur when normal fetal neuroblasts (precursors of the sympathetic nervous system) do not develop into mature cells. Instead, they continue to grow and divide due to alterations in the DNA sequence of certain genes, although how these changes affect the growth of neuroblastoma cells has not yet been deciphered. However, it has been described that in most cases these changes are randomly acquired (sporadic) although it is also unknown what causes them to appear. Only in a low percentage are variants acquired from the parents. In most cases of neuroblastoma, the cause is never identified.
There are no known environmental factors (such as exposure to chemicals or radiation during the mother's pregnancy or in early childhood) that increase the likelihood of neuroblastoma. In addition to the hereditary factor, which is rare in this condition, only the following risk factors have been described:
- Age: it is more frequent in infants and very young children. It is very rare in those older than 10 years.
- Congenital defects: certain birth defects could imply an increased risk.
Neuroblastoma most often arises sporadically and only in about 1-2% of cases does it run in families. Despite the multitude of studies in this context, the heritability of sporadic neuroblastoma remains poorly understood, however, a genome-wide association study of over 2000 neuroblastoma cases and over 6000 controls has identified 6 susceptibility loci not only in tumor onset but also in disease progression.
The most frequent signs and symptoms of neuroblastoma are due to the pressure of the tumor mass according to its location, and in the most severe cases to the possible metastasis that may occur. Symptoms may include:
- Lump or mass in the abdomen, neck, chest or pelvis depending on where the tumor occurs.
- Loss of appetite, nausea, weight loss, stomach pain, bloating, changes in bowel habits, difficulty urinating.
- Eye changes such as black eyes, drooping eyelids, pupil that does not contract, vision problems.
- Chest pain, shortness of breath, persistent cough.
- Painless bluish lumps under the skin.
- Bone pain, fever, irritability, apathy.
- Back pains.
- Pain or numbness in the lower extremities, inability to stand up, frequent stumbling.
There are no known environmental or lifestyle-related causes and the risks currently identified cannot be modified. It has been suggested that folic acid or vitamin supplementation in pregnant women could reduce the risk, but these data have not been contrasted.
In case of family history, the usefulness of genetic counseling has not been clarified either, given the low frequency of hereditary neuroblastoma.
13.5 million variants
Van Heerden J et al. Reporting Incidences of Neuroblastoma in Various Resource Settings. JCO Glob Oncol. 2021 Jun;7:947-964.