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Prognosis and survival for neuroblastoma
If your child has neuroblastoma, you will have questions about their prognosis. A prognosis is the doctor’s best estimate of how cancer will affect someone and how it will respond to treatment. Prognosis and survival depend on many factors. Only a doctor familiar with your child’s medical history, the type, stage and other features of the cancer, the treatments chosen and the response to treatment can put all of this information together with survival statistics to arrive at a prognosis.
A prognostic factor is an aspect of the cancer or a characteristic of the child that the doctor will consider when making a prognosis. A predictive factor influences how a cancer will respond to a certain treatment. Prognostic and predictive factors are often discussed together. They both play a part in deciding on a treatment plan and a prognosis.
The following are prognostic and predictive factors for neuroblastoma.
Children younger than 18 months of age usually have a better outcome.
Tumour histology is what the cancer cells look like under the microscope and predicts how they behave. Doctors may use a classification system, such as the Shimada classification system, to determine if a tumour has a favourable or unfavourable histology.
Tumours with a favourable histology have more differentiated cancer cells, which means the cancer cells look and act more like normal cells. The cancer cells are also slower growing.
Tumours with an unfavourable histology often have less differentiated cancer cells, which means the cancer cells are very different from normal cells. The cancer cells are usually faster growing.
The earlier the stage at diagnosis, the better the prognosis. Surgery is the only treatment that most children with localized neuroblastoma need. Children with metastatic neuroblastoma need more intensive treatment with a combination of therapies.
Response to treatment
High-risk neuroblastoma that doesn’t respond well to initial induction chemotherapy (for example, if neuroblastoma remains in the bone marrow or if there is little improvement in the extent of disease shown on an MIBG scan) often has a poorer prognosis.
The lower the risk group, the better the prognosis. Low-risk neuroblastoma responds better to treatment, requires less treatment and is less likely to come back (recur) than high-risk neuroblastoma.
DNA ploidy (DNA index) is the amount of DNA content in each cell. Healthy cells with a normal amount of DNA are classified as diploid and are given a DNA index of 1. Neuroblastoma cells that have excess (more than a normal amount of) DNA are classified as hyperdiploid and are given a DNA index greater than 1 (DNA index > 1).
Diploid (DNA index = 1) tumours tend to be less responsive to treatment and often need more aggressive therapy. Hyperdiploid (DNA index > 1) tumours tend to respond better to treatment and usually have a better prognosis.
MYCN is a gene that regulates cell growth. A single copy of the gene (described as non-amplified) is normal and is linked with a less aggressive form of cancer. Multiple extra copies of the gene (described as amplification) are usually seen in more aggressive tumours.
These changes can be losses or gains (fewer or more copies) of whole chromosomes (called numerical chromosomal aberrations) or losses or gains of just parts of individual chromosomes (called segmental chromosomal aberrations). Tumours with segmental chromosomal aberrations have a less favourable prognosis than tumours with only numerical abnormalities.
The presence of an ALK gene mutation is not clearly associated with a difference in prognosis. But patients with ALK mutations may be eligible to receive specific treatments (with ALK inhibitors) on clinical trials.