Wilms Tumour is a fast growing tumour of the kidneys that occurs in about 7.5% of children with BWS. However, Wilms tumour is one of modern medicine’s success stories. Statistics now show that 92% of children with Wilms tumour are cured; in those with favourable histology (cell type) the cure rate is 95%. Experience has shown that children treated for Wilms tumour can be regarded as cured if they survive for 2 years without any sign that the tumour has returned.
Wilms tumour may be suspected following an abdominal ultrasound scan.
Usually the parents notice a large painless swelling on one side of the abdomen. Occasionally the tumour may bleed slightly and this can cause irritation in the area, which may be painful. There may be blood in the child’s urine or the blood pressure may be raised. The child may also have a fever, upset stomach, weight loss or lack of appetite.
The following tests may be carried out: blood tests, urine tests, chest x-rays, ultrasound scans or MRI or CT scans, including scans of the chest to check for any spread of the disease. This process is known as staging. Final diagnosis, however, depends on obtaining a biopsy (tissue sample from the mass), and examining it under a microscope in order to verify that it has the characteristics of a Wilm’s tumor.
The prognosis for children with Wilms tumour depends largely on the stage, or extent, of the disease at the time of diagnosis and on certain microscopic features of the cancer cells, assessed after surgery to remove the kidney and tumour.
The tumour is confined to the kidney and is completely removed surgically. About 40% of children diagnosed as having Wilms tumour have stage I disease.
The tumour extends beyond the kidney but is still completely removed by surgery. Almost 20% of patients are in this group.
The cancer is found in surrounding tissues, lymph nodes or blood vessels in the abdomen which has not been be entirely removed by surgery. About 20% of children with Wilms are in stage III.
Cancer cells have spread and formed secondary tumours at distant sites, most commonly the lungs, liver, bone and brain. About 15% of Wilms cases are described as stage IV.
Cancer is bilateral, affecting both kidneys at the time of diagnosis. The disease is in stage V in about 5% of Wilms tumour cases.
The vast majority of children with kidney cancer (about 90%) have cell types described as favourable.
All children with Wilms tumour will have surgery. Initially this may only be a biopsy to confirm the diagnosis. Chemotherapy may then be given to shrink the tumour before the kidney is removed (nephrectomy). Sometimes nephrectomy is performed first and chemotherapy is given afterwards. During surgery, the surrounding lymph nodes, the area around the kidneys, and the entire abdomen will also be examined. The next steps of treatment depend on whether/where the cancer has spread. Samples of the tumor are also examined under a microscope to determine particular characteristics of the cells making up the tumor. Depending on the stage of the disease at diagnosis, radiotherapy may be given to the side of the abdomen where the tumour was found.
When one kidney is removed the other will be able to function as normal and work for both kidneys. Your child will be closely followed up to check for any recurrence. Most children with Wilms tumour are cured, and if the cancer comes back it is usually within the first two years.
Screening Protocol for Abdominal Tumours
Because Wilms tumour and hepatoblastoma (liver tumour) are fast growing tumours, it is recommended that all BWS children should have 3 monthly abdominal ultrasound scans. Early identification of the tumours may lead to improved survival and sometimes less aggressive treatments. A recent study has shown that children with BWS, who developed Wilms tumour, and had 3 monthly scans usually have stage 1, 2 or 3 tumours and not stage 4 or 5. As the risk of Wilms tumour diminishes after the age of 7 or 8 years abdominal ultrasound scans need not be continued past this age.
Hepatoblastoma can also be detected by ultrasound. However, because not all of the liver can be viewed by ultrasound, it is recommended that a blood test to measure alpha-feta-protein (afp) is also carried out every three months. (Afp levels are raised in hepatoblastoma.) Unlike Wilms tumour the risk of hepatoblastoma drops off after the age of three years and so the blood tests need not be continued after this.