Depending on the location of the tumor and other factors, doctors use different tests to diagnose neuroblastoma. Often these texts include x-rays or other imaging, like CT scans or MRIs, to determine the location and size of the neuroblastoma tumor. In about 90% of neuroblastoma cases, tumor cells produce elevated levels of hormones. The hormones are broken down by the body into acids called HVA and VMA, which are eliminated from the body in the urine. To diagnose neuroblastoma, your child may need to give a urine sample to evaluate HVA and VMA levels. High HVA to VMA ratio may indicate an undifferentiated, unfavorable tumor whereas a high VMA level may represent a more differentiated, less aggressive tumor. In addition, a complete blood count (CBC) and chemistry panel will give more information about kidney and liver function.
Once doctors have located the tumor, they take a biopsy to confirm the diagnosis and to develop the best treatment plan. Doctors will perform surgery to remove either part or the entirety of the tumor. Following surgery, a healthcare team will identify the exact type of tumor and its particular characteristics. These factors are important in determining the best treatment for your child. In some children, neuroblastoma will have spread to the bone marrow by the time of diagnosis. To evaluate your child, the healthcare team will perform a bone marrow aspirate and a bone marrow biopsy on both hips.
Determining Treatment and Risk of Relapse
After your child undergoes testing to identify the extent of tumor present and to learn about the biology or characteristics of the tumor cells, the information gathered will determine the likelihood of a recurrence of disease after treatment. Neuroblastoma is classified as low-, intermediate- or high-risk disease. The risk of relapse of neuroblastoma tumor is determined by the biology of the cancer cells, rather than when the diagnosis is made.
Factors that help determine the risk for relapse are:
- The age of the child at diagnosis: many children under 18 months have “low risk” or “intermediate risk” disease, and the cancer is less likely to recur in these children.
- Tumor Histopathology: Histopathology refers to the evaluation of tumor cells under a microscope. A pathologist will determine the type of cells in the tumor and will decide whether the tumor is neuroblastoma or one of the related, but less aggressive related tumors called ganglioneuroblastoma or ganglioneuroma.
- MYCN Status: MCYN is a gene that is involved in regulation of the growth of some cells, including neuroblasts. Tumor cells are examined to determine the number of copies of the gene within the tumor cell. A single copy (non-amplified) is normal. Multiple copies of the MYCN gene (amplified) are associated with a more aggressive tumor type.
- DNA Index: The DNA content (ploidy) of a tumor cell is compared to that of a normal cell. Normal cells have a DNA index of 1. A DNA index of more than 1 is associated with a better outcome in some groups of children with neuroblastoma.
- Chromosomes: Certain consistent changes have been identified in the chromosomes of neuroblastoma tumor cells and their presence can help to determine a risk classification.
- The stage of the disease: staging refers to the physical location of the primary tumor and the location of any secondary tumors (metastases).