In general, neuroblastoma is classified into 3 risk groups (low risk, intermediate risk, and high risk) using 5 prognostic factors, clinical stage, age, MYCN gene copy number in the tumor cells, International Neuroblastoma Pathology Classification, and number of chromosomes in tumor cells (expressed as DNA index), and a treatment option is selected based on the risk. According to the results to date, 3-year survival is estimated to be 90% in the low risk group, 60% to 80% in the intermediate risk group, and approximately 30% in the high risk group. The risk classification of Children's Oncology Group (COG) , which is widely used in the world, is shown below. In fact, this classification of risk groups is used with some modifications according to the objectives of each clinical study.
Low risk group
A child who meets any of the following 3 criteria is in the low risk group:
- Has a Stage 1, 2A, or 2B tumor without MYCN amplification
- Has a Stage 3 tumor without MYCN amplification, and is an infant
- Has a Stage 4S tumor with DNA index of 1 or higher, and is in good prognosis group according to the pathological classification
Intermediate risk group
A child who meets any of the following 4 criteria is in the intermediate risk group:
- Has a Stage 3 tumor without MYCN amplification, and is aged between 1 year and 1 1/2 years
- Has a Stage 4 tumor without MYCN amplification, and is an infant aged less than 1 year
- Has a Stage 4 tumor without MYCN amplification, is in good prognosis group according to the international pathological classification and has DNA index of 1 or greater, and is an infant aged between 1 year and 1 1/2 years
- Has a Stage 4S tumor without MYCN amplification, is in good prognosis group according to the international pathological classification or has DNA index of 1, and is an infant
High risk group
A child who meets any of the following 4 criteria is in the high risk group:
- Has a Stage 2A, 2B, 3, 4, or 4S tumor with MYCN amplification
- Has a Stage 3 tumor without MYCN amplification, is in poor prognosis group according to the international pathological classification, and is aged 1 1/2 years or older
- Has a Stage 4 tumor without MYCN amplification, and is aged 1 1/2 years or older
- Has a Stage 4 tumor without MYCN amplification, is in poor prognosis group according to the international pathological classification or has DNA index of 1, and is aged between 1 year and 1 1/2 years
Note: The risk group classification may change in the future if significance of new biological features, such as specific chromosomal abnormality or genetic abnormality, is fully understood.