What do the different stages of neuroblastoma mean? 

Neuroblastoma is divided into different stages, which describe how far the cancer has grown and spread. Doctors use the stage to help decide the best treatment plan for each child. Stages are closely linked to risk groups, but they are not the same thing. 

How are stages determined? 

Doctors use a system called the International Neuroblastoma Risk Group (INRG) staging system. You might see stages described as “L1”, “L2”, “M”, or “MS”: 

• L1: Localised tumour, not involving vital structures 
• L2: Localised tumour with some involvement of nearby structures 
• M: Metastatic (spread to distant parts of the body) 
• MS: Metastatic, but only to skin, liver, or bone marrow in children under 18 months 

This terminology is unique to neuroblastoma, and this is often used alongside more generic cancer staging language, where it can be described as Stage 1, 2 3, or 4. 

The main stages are: 

• Stage 1 (INRG stage L1): The cancer is localised and has not spread. It can be completely or almost completely removed by surgery. 

• Stage 2 (INRG stage L1): The cancer is localised and has not spread, but it cannot be completely removed by surgery. This is often because the tumour is close to important organs or blood vessels, making full removal unsafe. 

• Stage 3 (INRG stage L2): The tumour has begun to spread to nearby lymph nodes or structures but not to distant parts of the body. 

• Stage 4 (INRG stage M): The tumour has spread to distant parts of the body. This stage is usually considered 'high-risk' and is treated with a combination of chemotherapy, surgery, 
  radiotherapy, stem-cell transplant, and immunotherapy. Around half of children are diagnosed at Stage 4. This is common because neuroblastoma can be difficult to detect early. 

• Stage 4S (INRG stage MS): This stage is unique to young children (under 18 months). The cancer may have spread to the skin, liver, or a small amount of bone marrow, but not to bones. Stage 4S neuroblastoma can sometimes shrink or disappear on its own, so close observation may be recommended instead of immediate treatment. 

Your child’s medical team will explain which stage applies to your child and what this means for their treatment and outlook.