Neuroblastoma affects a very early form of nerve cells that develop during embryonic and fetal development, called neuroblasts. It is rare in children over 10 years and is most common in the first few years of life.
In many cases, the tumor is difficult to detect while it is in the early stages and is not usually diagnosed until the more advanced stages of disease. However, the earlier the condition is diagnosed, the greater chance a patient has of surviving and the less chance there is of disease recurrence.
Neuroblastoma is one of the most common childhood cancers and forms nearly 6% of all cancers worldwide.
Screening all children for this cancer can help in two important ways:
- The cancer may be detected early
- Treatment can be started early, increasing the chance of recovery and survival
The term "screening" refers to testing for a disease or condition in members of a population regardless of whether or not they have symptoms.
To screen for neuroblastoma, possible methods include testing the urine to detect the presence of cathecholamines such as adrenaline and noradrenaline which are released by neuroblastoma tumors. In people with neuroblastoma, the blood and urine levels of the cathecholamine breakdown products (metabolites) are high enough to be detected.
The metabolites most commonly checked for include homovanillic acid (HVA) and vanillylmandelic acid (VMA). Japan has been using this test to screen babies for neuroblastoma for the past three decades.
Another method is by using ultrasound examination of the mother while she is pregnant to check for tumors within the unborn baby. Ultrasounds are routinely performed to assess the growth and development of the fetus within the womb.
However, many studies have failed to show any benefit from screening for neuroblastomas in healthy children. Testing infants when they are less than a year old does help in diagnosing and detecting a large number of neuroblastomas that would otherwise have been missed, but these tumors usually resolve without treatment or do not lead to any long-lasting harm.
Overall, studies have shown that screening all children has not decreased the number of children diagnosed with advanced, metastasized disease, or that it has saved lives on the whole. Canada and Germany also used to screen babies' urine for neuroblastoma but have abandoned the test due to lack of evidence that it saves lives or prevents the onset and diagnosis of advanced disease.