Staging & risk stratification in childhood cancer — what parents need to know

Staging is the process of measuring how far a cancer has grown from where it started and whether it has spread to nearby lymph nodes or to other parts of the body. Doctors use staging because the extent of the disease — not just the cancer type — shapes what treatment is needed and how intensively it should be delivered. A child whose cancer is confined to one area is in a different situation from a child whose cancer has reached the bloodstream or distant organs, even if the cancer type is the same. Knowing the stage lets the paediatric oncology team design the right treatment for the right child, avoiding both under-treatment and unnecessary side effects from over-treatment.

No — different childhood cancers use different staging systems because they spread in different ways. Solid tumours such as Wilms tumour (kidney cancer) and neuroblastoma (adrenal cancer) use staging systems numbered I to IV, where Stage I is localised and Stage IV means widespread spread. Leukaemias — which are cancers of the blood — do not use the same numbered stage system. Instead, leukaemia staging focuses on the number of cancer cells in the blood and bone marrow, and on specific chromosomal changes in those cells. Lymphomas (cancers of the lymph glands) use yet another system. Your child's oncologist will explain which system applies and what stage means for your specific situation.

Staging relies on a combination of imaging and laboratory tests. PET-CT is one of the most important staging tools — it maps metabolically active tumour cells across the entire body and reveals whether cancer has spread beyond the primary site. MRI and CT scans are used to measure the exact size of the primary tumour and to look at nearby lymph nodes. A bone marrow biopsy may be needed to check whether cancer cells have reached the marrow. In leukaemia, a lumbar puncture (spinal tap) is performed to see whether cancer cells are present in the fluid surrounding the brain and spinal cord. Together, these results give the oncology team a complete picture of how far the cancer has spread.

Risk stratification means placing a child's cancer into a risk group — typically low, standard, or high risk — based on a combination of features that predict how the cancer is likely to behave. These features include the stage, the child's age at diagnosis, the specific subtype of cancer identified on biopsy, the results of molecular testing (such as chromosome changes), and how the cancer responds to the first few weeks of treatment. Risk group determines treatment intensity: children in a low-risk group may need gentler treatment with fewer side effects, while children in a high-risk group receive more intensive therapy. Risk stratification is how modern oncology avoids treating every child the same — it means the treatment is as precisely matched to the child as possible.

A higher stage means the cancer is more widespread, and treatment will be more intensive — but it does not mean treatment cannot work. Many children with advanced-stage childhood cancers respond well to treatment, because several childhood cancers are biologically more sensitive to therapy than adult cancers of the same type. The stage is one important piece of information, not a fixed prediction about your child's outcome. At CION Cancer Clinics, every child's case is reviewed by a tumour board — a group of specialists including medical, surgical, and radiation oncologists — who use the stage alongside molecular test results and risk group to build a personalised treatment plan. We walk this journey with you, step by step.

Staging investigations usually run in parallel with confirmatory tests such as biopsy, rather than waiting until the diagnosis is fully confirmed. For many childhood cancers, the team begins ordering PET-CT, MRI, or bone marrow tests as soon as cancer is strongly suspected. In leukaemia, because treatment is time-sensitive, full staging and the start of therapy can happen within days of the bone marrow biopsy confirming the diagnosis. For solid tumours, completing imaging and waiting for pathology and molecular results typically takes one to three weeks before staging is finalised. Your oncologist will keep you informed at each step and will explain what the results mean before any treatment decision is made.