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This information is about Wilms' tumour in children. You may find it helpful to read it alongside the Macmillan/CCLG booklet A parent’s guide to children’s cancer|, which contains more information about children's cancers, diagnosis, treatment and support services.
About 70 children in the UK develop a Wilms' tumour each year. It most often affects children under the age of five.
Structure of the kidney
View a large copy of the structure of the kidney image|
Wilms' tumour was named after Dr Max Wilms, who first described it. It's a type of kidney cancer|. It's thought to come from very specialised cells in the embryo known as metanephric blastema. These cells are involved in the development of the child's kidneys while they're in the womb. These cells usually disappear at birth, but in many children with Wilms' tumour, cells called nephrogenic rests can still be found.
The kidneys are a pair of organs found at the back of the abdomen. They clean the blood to remove excess fluids and waste products. These are then converted into urine.
In most children the causes of Wilms' tumour are unknown. Very rarely, people who have Wilms' tumour also have other particular conditions present at birth (congenital malformations), such as a lack of an iris in the eye (aniridia), abnormalities of the genitals and a condition where one side of the body is slightly larger than the other (hemihypertrophy). In 1 in 100 people with Wilms' tumour, another family member will also have Wilms' tumour.
The most common symptom is a swelling in the abdomen, which is usually painless. Occasionally, the tumour may bleed slightly and this can cause irritation in the kidney area, which may be painful. There may be blood in your child’s urine, or their blood pressure may be raised. The child may also have a high temperature (fever), upset stomach, weight loss or a lack of appetite|.
A variety of tests and investigations| may be needed to diagnose a Wilms' tumour. These may include a biopsy, where a sample of tissue is taken from the tumour to confirm the diagnosis. Urine and blood samples will also be taken to check your child's kidney function and general health.
An abdominal ultrasound scan, MRI and CT scans are often done, and these will help the doctors to understand as much as possible about the tumour. Scans of the chest and liver may also be taken to check for any spread of the disease. This is known as staging.
Any tests and investigations that your child needs will be explained to you. The booklet A parent’s guide to children’s cancer gives details of what the tests and scans involve.
The stage of a cancer is a term used to describe its size and whether it has spread beyond its original site. Knowing the particular type and the stage of the cancer helps doctors decide on the most appropriate treatment.
In Wilms' tumour, it's common for staging to happen after an initial course of chemotherapy followed by surgery. This means you may not know the exact stage of your child's tumour straight away. An exception is that babies under six months old usually have surgery straight away.
A commonly used staging system for Wilms' tumours is described below:
If the tumour comes back after initial treatment, this is known as recurrent cancer, or relapse.
Treatment will depend on a number of factors, including how the cells appear under the microscope (histology) and the stage of the tumour. Treatment may include chemotherapy|, radiotherapy| or surgery|.
All children with Wilms' tumour will have surgery. Initially, this may only involve taking a small sample of cells from the tumour to confirm the diagnosis. This is called a biopsy.
The appearance of the Wilms' tumour cells when they are examined under a microscope is important. About 1 in 10 to 1 in 20 (5-10%) of Wilms' tumours have an appearance called anaplasia. This is considered a 'higher-risk' tumour and requires a stronger treatment.
When tumours are operated on after chemotherapy, a second 'high-risk' category of Wilms' tumour may be identified. This is called a 'blastemal' type, because it contains lots of early cells known as blastemal cells. These cells have survived the pre-surgery chemotherapy.
Other, less common types of kidney tumours may occur in children. These are usually only recognised after surgery to obtain a tumour sample. Two cancerous types of tumour are clear cell sarcoma and malignant rhabdoid tumour of the kidney. These are treated in a similar way to 'high-risk' Wilms' tumours.
A non-cancerous (benign) tumour that occurs in very young children is known as congenital mesoblastic nephroma. This usually only needs surgery and no other treatment.
If possible, the Wilms' tumour will be removed by surgery, either at diagnosis or following chemotherapy. This usually involves removing all of the kidney (nephrectomy), but occasionally only part of the kidney (partial nephrectomy) needs to be removed.
Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. It's usually given as injections and drips (infusions) into a vein. Chemotherapy given before surgery is called neoadjuvant chemotherapy.
What doctors find out about the tumour after surgery, for example how the cells look under the microscope and how far the cancer has spread, helps them decide whether chemotherapy should be given (adjuvant chemotherapy). This is to help reduce the risk of the cancer coming back (recurring).
Depending on the stage of the tumour at diagnosis, radiotherapy may also be given to the area of the affected kidney or to the whole abdomen. Radiotherapy treats cancer by using high-energy rays to destroy the cancer cells, while doing as little harm as possible to normal cells.
If the tumour can't be removed by surgery, then chemotherapy and radiotherapy may be given to shrink the tumour. Once the tumour has shrunk, surgery can then often remove it. Further chemotherapy and radiotherapy may also be given. If there are secondary tumours, these may be treated with radiotherapy or chemotherapy.
Bilateral Wilms' tumour affects both kidneys. This cancer occurs in about 1 in 20 cases. Treatment may involve two operations, a few weeks apart. The aim of the treatment is to remove as much of the cancer as possible, while leaving as much healthy kidney as possible. Chemotherapy is always given; sometimes radiotherapy is needed as well.
Treatment for Wilms' tumours often causes side effects, and your child’s doctor will discuss this with you before treatment starts. Side effects can include feeling sick (nausea) and being sick (vomiting)|, hair loss|, bruising and bleeding, tiredness|, diarrhoea| and an increased risk of infection|.
A small number of children may develop late side effects| many years later, sometimes many years later. These include a possible reduction in bone growth, infertility, a change in the way the heart and lungs work, and a slight increase in their risk of developing another cancer in later life. Although infertility| can be a possible late side effect, this is rare.
Your child's doctor or nurse will talk to you about any possible late side effects. There's more detailed information about these late side effects in the booklet A parent’s guide to children’s cancer.
Many children have their treatment as part of a clinical research trial|. Trials aim to improve our understanding of the best way to treat an illness, usually by comparing the standard treatment with a new or modified version.
Specialist doctors carry out trials for children's cancer. If appropriate, your child's medical team will talk to you about taking part in a clinical trial, and will answer any questions you have. Written information is provided to help explain things.
Taking part in a research trial is completely voluntary, and you'll be given plenty of time to decide if it's right for your child.
Most children with Wilms' tumour are cured. If the cancer comes back, it's usually within the first two years. When one kidney is removed, the other will be able to work normally and can take over the work of the other kidney.
Very few children have long-term kidney problems. Your child will have regular follow-ups| to check for any recurrence.
If you have specific concerns about your child’s condition and treatment, it's best to discuss them with your child’s doctor, who knows the situation in detail.
As a parent, the fact that your child has cancer is one of the worst situations you can be faced with. You may have many different emotions, such as fear, guilt, sadness, anger and uncertainty. These are all normal reactions| and are part of the process that many parents go through at such a difficult time.
It's not possible to address here all of the feelings you may have. However, the booklet A parent’s guide to children’s cancer talks about the emotional impact of caring for a child with cancer and suggests sources of help and support.
Your child may have a variety of powerful emotions| throughout their experience of cancer. The parent's guide discusses this further and talks about how you can support your child|.
Our booklet Peppermint Ward| is a storybook for younger children with cancer. It looks at the issues that they and their family may face and helps them to explore their feelings.
This section has been compiled using information from a number of reliable sources, including:
For answers, support or just a chat, call the Macmillan Support Line free (Monday to Friday, 9am-8pm)
If you have any questions about cancer, need support or just want someone to talk to, ask Macmillan.