Treatment for childhood neuroblastoma has steadily improved in the last 2 decades. In the 1960s, over 75 percent of all children with neuroblastoma died. Now, the success rate of treatment varies with the stage at diagnosis.

To determine the best possible treatment for each child, doctors consider the stage of disease as well as the factors below to decide whether the child is in a low-, intermediate-, or high-risk category:

•  MYCN amplification. MYCN is a normal gene that contributes to some neuroblastomas developing or becoming very aggressive. Amplification means that instead of two copies of MYCN in every cell, the neuroblastoma cells have 100 to 200 copies of the gene. This occurs in 20 to 25 percent of tumors.

•  Tumor pathology. Using the International Neuroblastoma Pathology Classification method, the tumor is graded as favorable or unfavorable, based mainly on how it looks under a microscope (called histopathologic classification).

•  DNA index. This is a measurement of the amount of DNA material in neuroblastoma cells. Diploidy (also known as a DNA index of 1, corresponding to 46 chromosomes) is the normal amount of DNA in a human cell. Children with diploid or near-diploid tumors tend to have a worse outcome. Having more than the diploid amount of DNA (or chromosomes) is called hyperdiploidy (also known as DNA index >1). Most cells in hyperdiploid tumors have 60 to 70 chromosomes, which is associated with a favorable outcome.

•  Child’s age. Previously, oncologists thought that an age of 12 months or younger was associated with favorable outcomes. However, several recent studies suggest that 18 months is a better age cut-off to distinguish likely outcomes.