Neuroblastoma Risk Groups

Risk groups are used to help predict how likely it is that a child with neuroblastoma can be cured (and therefore how intensive treatment might need to be). For example, a child in a low-risk group can often be cured with limited treatment, such as surgery alone. Children in higher risk groups often need more intensive treatment to have the best chance of being cured.

The risk groups are based on the stage (extent) of the cancer, as well as other factors that can affect a child’s prognosis (outlook), such as their age. (See Neuroblastoma Stages and Prognostic Markers.)

The risk groups included here are commonly accepted standard risk groups in the United States. Other internationally used risk groups are being tested in clinical trials.

Children’s Oncology Group (COG) risk groups

The Children’s Oncology Group (COG, the major group of doctors who treat childhood cancer in the US) risk group system was initially based on the International Neuroblastoma Staging System (INSS) staging system, but is now transitioning to using the International Neuroblastoma Risk Group Staging System (INRGSS), along with the major prognostic factors, all of which are described in Neuroblastoma Stages and Prognostic Markers. These are combined to place children into 3 different risk groups:

• Low risk
• Intermediate risk
• High risk

These risk groups are based on what is known about neuroblastoma and how it is treated. As new research provides more information, the risk groups may change over time. For example, in recent treatment recommendations the age cut-off for some of these categories has been revised from up to 12 months to up to 18 months.

International Neuroblastoma Risk Group (INRG) classification

The International Neuroblastoma Risk Group (INRG) classification is a newer system that is now being used to help researchers in different countries compare results and work together to find the best treatments. This system is based on the INRGSS staging system, which includes the image-defined risk factors (IDRFs), as well as many of the prognostic factors listed in Neuroblastoma Stages and Prognostic Markers, such as:

• The child’s age
• Tumor histology (how the tumor looks under the microscope)
• The presence or absence of MYCN gene amplification in tumor cells
• Certain changes in chromosome 11 (known as an 11q aberration) in tumor cells
• DNA ploidy (the total number of chromosomes in the tumor cells)

The INRG classification uses these factors to put children into 16 different pre-treatment groups (lettered A through R). Each pre-treatment group falls into 1 of 4 overall risk groups:

• Very low risk
• Low risk
• Intermediate risk
• High risk

This system will most likely be used in addition to the COG risk classification system in the United States.

The risk groups for neuroblastoma are complex and can be confusing. If you are unsure about your child’s risk group and what it means, ask your child’s doctor to explain it to you in a way you can understand.