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Children with Wilms tumour and their parents may have questions about prognosis and survival. Prognosis and survival depend on many factors. Only a doctor familiar with a child’s medical history, type of cancer, stage, characteristics of the cancer, treatments chosen and response to treatment can put all of this information together with survival statistics to arrive at a prognosis.
A prognosis is the doctor’s best estimate of how cancer will affect a child, and how it will respond to treatment. 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 and they both play a part in deciding on a treatment plan and a prognosis.
The following are prognostic and predictive factors for Wilms tumour.
The type of Wilms tumour is an important prognostic factor. Tumours with favourable histology (no anaplasia, which means that the cells look, act and divide like normal cells) have a better prognosis than those with unfavourable histology (anaplasia is present). Diffuse anaplastic histology (anaplasia found throughout the tumour) is associated with higher rates of relapse and worse survival than favourable histology.
The earlier the stage of Wilms tumour, the more favourable the prognosis. Cancer that has spread to the lymph nodes or to other areas of the body has a poorer prognosis.
Younger age is a more favourable prognostic factor. Children younger than 2 years old have a significantly better prognosis than older children. This may be due to the fact that anaplasia is not common in children younger than 2 years old diagnosed with Wilms tumour.
Some tumour cells have certain chromosome changes that can affect prognosis. Loss of heterozygosity (LOH) is when one allele, or form, of a gene within tumour cells stops working. This can mean that a gene that normally helps limit the growth of cancer cells (called a tumour suppressor gene) stops working. LOH for DNA markers on chromosomes 1p and 16q has been associated with a higher rate of recurrence and poorer prognosis in people with favourable histology Wilms tumours.
Smaller tumours have a more favourable prognosis than larger tumours.
Several genetic syndromes, including Beckwith-Wiedemann, Denys-Drash and WAGR, are associated with the risk of developing Wilms tumours in both kidneys. In general, children with these genetic syndromes have tumours that respond well to therapy and no increased risk of relapse. However, there is a much higher incidence of serious kidney disease (end-stage renal disease, or ESRD) in children with Wilms tumours in both kidneys.
The prognosis for a recurrent Wilms tumour is generally better if the tumour has the following features: