What is cancer of the kidney?

Cancers affecting the kidneys are also known as renal tumours.  

Wilms’ tumour is a type of kidney cancer, also known as nephroblastoma, and is the most common type of kidney cancer in children, accounting for over 90% of cases.  

What causes childhood kidney cancer?

Your kidneys are two bean-shaped organs that are found in the upper back part of the abdomen. They are responsible for ridding the body of waste from the blood, filtering water and producing urine. A kidney tumour (often known as renal tumour) in children develops from nephroblasts, the immature cells from which the kidneys develop. These cells often don’t mature normally, instead, they remain present in a child’s kidney after birth, and then they start to grow at a rapid and uncontrolled rate, becoming a large mass of tiny, immature cells. Other types of renal tumours include rhabdoid renal tumour, kidney sarcomas and renal carcinoma.



Incidence Rates

Kidney tumours account for 5% of all childhood cancers in Great Britain. Nine out of ten cases (90%) are nephroblastoma (also known as Wilms’ tumour), affecting around 70 children a year in the UK.

Unilateral tumours occur equally often in boys and girls, but girls are twice as likely to be diagnosed with bilateral tumours (occurrence in both kidneys). A majority of kidney cancer diagnosis happens aged five and under.

Kidney Cancer Survival Rate

The prognosis for most children with kidney tumours is good, with most being curable. If the tumour comes back after initial treatment, this is known as recurrent cancer, or relapse. If the cancer comes back, it is usually within the first two years.

What are the symptoms of a Kidney Tumour?

The most kidney cancer symptom (or renal tumour) is a swelling in the abdomen, which is usually painless.

Sometimes there may also be:  

  • Blood in the child’s urine
  • Blood pressure may be raised
  • Fever
  • Upset stomach  
  • Weight loss or lack of appetite






What would you expect to happen first, when you see your GP?

A variety of tests and investigations will need to be carried out before a kidney tumour is diagnosed. Urine and blood samples will be taken to check kidney function. An abdominal ultrasound scan and CT scan are often done. Scans of the chest and liver may be taken to check for any spread of the disease. 

A biopsy will be taken to provide further information about the tumour. Around five per cent of Wilms’ tumours have ‘unfavourable’ histology, characterised by ‘anaplastic’ cells that are harder to eradicate. 

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 to decide on the most appropriate treatment

What would you expect to happen during treatment?

Treatment will depend on a number of facts including the histology of the tumour. That means how the cells appear under the microscope, as well as the stage of the disease. 

If possible the tumour will be removed by surgery, either at diagnosis or following a course of chemotherapy to shrink the tumour. Sometimes radiotherapy may be used to shrink the tumour. 

Surgery usually involves removing the whole kidney, a nephrectomy, but occasionally only part of the kidney needs to be removed, a partial nephrectomy. Examination of the excised tumour will provide doctors with further information about the nature of the tumour and will determine what further treatment is required. 

Most tumours are ‘standard risk’. Some are ‘low risk’ and require less additional treatment than the standard risk tumours. Two types of Wilms’ tumour – anaplastic and blastemal – are ‘high risk’ and require more intensive treatment. 

Chemotherapy is usually given after the surgery to reduce the risk of the cancer returning. Depending on the stage of the tumour, radiotherapy may also be used. 

In children with bilateral disease, the aim of surgery is to remove as much of the cancer as possible, while leaving as much healthy kidney as possible. Chemotherapy will always be given and sometimes radiotherapy will also be used.  

Treatment follow up

The child will have regular follow-ups to check for any recurrence of the cancer and for any problems that may arise as a result of the treatment they were given (late effects).

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.

Long-term and late effects of treatment

Side effects of treatment

Treatment often causes side effects and these will be discussed with you before treatment starts. 

The possible side effects of chemotherapy may include: 

  • Nausea and vomiting 
  • Hair loss 
  • Reduced resistance to infection 
  • Bruising and bleeding 
  • Tiredness 
  • Diarrhoea 

These problems are all temporary and can be minimised with good supportive care. 

A small number of children may develop other side effects, sometimes many years later. These can include  

  • Reduction in normal bone growth  
  • Reduced fertility  
  • Change in heart function  
  • Small increase in the risk of developing a second cancer later in life 


Many children have their treatment as part of a clinical trial.

Trials aim to improve understanding of the best way to treat the cancer, usually by comparing the standard treatment with a new or modified version.

If appropriate, the child’s medical team will discuss participation in a relevant trial. Participation is optional but may offer the opportunity to receive new treatments.

Children with Cancer UK is funding an important project at the Institute of Child Health which could help to improve treatments for Wilms’ tumour.

Read more: Molecular evolution of Wilms’ tumour

Alice's Story

Jane with her daughter, Alice, who was diagnosed with a kidney cancer, Wilms' tumourRead Alice’s victory against Wilms’ tumour, told by her mum, Jane:

In March 2014 I had noticed that Alice’s tummy seemed swollen over a few weeks, and it was larger on one side. Initially, I wasn’t overly worried as my son had had a toddler ‘pot belly’, so I thought it was that.

But then Alice started to really lose her appetite. She has always been a fussy eater but now she was going for whole days eating hardly anything, and saying she felt full after a few spoonfuls.

My husband went to the GP with Alice and at 5pm Andrew called me to say the GP had told them to go straight to QMC (Queens Medical Centre, Nottingham). He sounded really worried so I left work and dashed over to meet them.

We were sent straight to the medical assessment unit where several doctors examined Alice. I was worried but still didn’t think it would be serious. At around 10pm a consultant came to see us and delivered the devastating news – that it looked extremely likely that Alice had kidney cancer, Wilms’ tumour. At that moment our world fell apart and I could only wonder at how this could be happening when she seemed so well? I also thought of all the worst case scenarios and spent most of the night in tears.

The treatment plan would be six weeks of chemo before surgery to remove her kidney and the Wilms’ tumour. I was terrified at the prospect of all of this and the possible side effects and I got very upset at the thought of what our beautiful girl would have to go through. But we tried to remain positive and decided on a ‘one day at a time’ approach.

We knew the tumour had spread into her vein and that removing it would be tricky. Seeing her go down to the operating theatre that day was awful. But we knew we had to put our trust in the surgeons if we wanted to get her better. After the longest six hours of my life she was back and the operation to remove her Wilms’ tumour and kidney was a success.

After surgery Alice had nine sessions of radiotherapy and six more months of weekly chemo to ensure the cancer was completely eradicated. We were very lucky that she has only been admitted to hospital a few times so we have been able to be mostly at home. This allowed Alice to start full-time school in September, which she loves!

If you’ve been touched by Alice’s journey, help us invest in the high quality research that really matters which would otherwise go unfunded, helping to support children with cancer so they can be with their families for longer.

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