Prognosis and survival for Wilms tumour

A prognosis is the doctorʼs best estimate of how cancer will affect your child and how it will respond to treatment. Survival is the percentage of children with a disease who are alive at some point in time after their diagnosis. Prognosis and survival depend on many factors.

The doctor will look at certain aspects of the cancer as well as characteristics of the child (such as their age). These are called prognostic factors. The doctor will also look at predictive factors, which influence how a cancer will respond to a certain treatment and how likely it is that the cancer will come back after treatment.

Prognostic and predictive factors are often discussed together. They both play a part in deciding on a prognosis and a treatment plan just for your child. Only a doctor familiar with your childʼs 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 and chances of survival.

The following are prognostic and predictive factors for Wilms tumour.

The type of Wilms tumour is determined by the histology. Histology is how different the cancer cells are from normal kidney cells when looked under a microscope. There are 2 types of Wilms tumours. Favourable histology means that the cells look quite normal and they donʼt have anaplasia. Anaplastic (unfavourable) histology means that the cancer cells look and act very differently from normal kidney cells.

Tumours with favourable histology have a better prognosis and respond better to chemotherapy and radiation therapy than tumours with anaplastic histology.

Diffuse anaplastic histology (anaplasia found throughout the tumour) has a worse prognosis than focal anaplastic histology (anaplasia found in one area or in a few specific areas of the tumour).

Wilms tumours can also be categorized based on how the cancer cells look after chemotherapy and before surgery. Blastemal-predominant tumours (tumours with lots of anaplasia left after chemotherapy) have a worse prognosis. Completely necrotic tumours (tumours in which all cancer 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, but is still very treatable.

Chromosomes are the parts of cells that hold a personʼs genetic information (DNA) . Doctors look at cells removed from the tumour to see if there are changes to the chromosomes in the cancer cells. Some changes to chromosomes can affect prognosis.

Loss of heterozygosity (LOH) is when one copy of a segment of DNA containing a gene or groups of 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 of favourable histology Wilms tumours increases the risk of recurrence and means that the cancer has a poorer prognosis than favourable histology tumours without these chromosome changes.

Having an extra copy of a part of a chromosome is called a gain or amplification. A gain of a section of chromosome 1 (called a 1q gain) increases the risk of recurrence.

The TP53 gene signals the formation of a protein that keeps cells from growing or dividing too fast or in an uncontrolled way. A mutation, or change, of the TP53 gene is common in anaplastic Wilms tumours. Anaplastic tumours with mutated TP53 donʼt respond well to chemotherapy, so they have a poor prognosis.

Younger age is a favourable prognostic factor. Wilms tumour in children under 2 has a better prognosis than Wilms tumour in older children.

Several inherited conditions, including Beckwith-Wiedemann syndrome, Denys-Drash syndrome and WAGR syndrome, are associated with the risk of developing Wilms tumours in both kidneys. In general, Wilms tumour in children with these inherited conditions responds well to treatment and has no increased risk of recurrence. But there is a higher incidence of serious kidney disease (end-stage renal disease, or ESRD) in children with Wilms tumours in both kidneys.