Prognosis and survival for Wilms tumour

If your child has Wilms tumour, you will have questions about their prognosis. A prognosis is the doctor’s best estimate of how cancer will affect someone and how well it will respond to treatment. Prognosis and survival depend on many factors. Only a doctor familiar with your child’s medical history, the type and 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 Wilms tumour.

The type of Wilms tumour is an important prognostic factor. Tumours with favourable histology have a better prognosis than those with anaplastic (unfavourable) histology. Diffuse anaplastic histology (anaplasia found throughout the tumour) is associated with higher rates of relapse and worse survival than a favourable histology.

In children who have had chemotherapy before surgery, several other types of tumour can be determined. Blastemal-predominant tumours (tumours with lots of anaplasia left after chemotherapy) have a poorer prognosis. Completely necrotic tumours (tumours where all cells have died with chemotherapy) have a better prognosis.

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.

Some tumour cells have certain chromosome changes that can affect prognosis. Loss of heterozygosity (LOH) is when one allele, or form, of a gene or genes 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 children with favourable histology Wilms tumour. Having too much of a section of chromosome may also be associated with a higher chance of recurrence. An example of this is the gain of a section of chromosome called 1q.

Younger age is a favourable prognostic factor. Children under 2 with favourable histology tumours that have not spread have a better prognosis than older children.

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. But there is a 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 a favourable histology
• no previous chemotherapy with doxorubicin (Adriamycin) was given
• no previous radiation therapy was given
• the recurrence happens at least 1 year after the initial diagnosis