Wilms tumour: Common childhood cancer of the kidney

September remains Childhood Cancer Month and we continue the discussion on the commonest childhood cancers.

The last article was on retinoblastoma, the most common cancer of the eye, and this week the spotlight is on the common childhood cancer of the kidney called Wilms tumour or nephroblastoma. 

It is the most common childhood cancer in the abdomen. Wilms tumour is thought to be caused by alteration or change of genes responsible for normal development of the genital and the urinary systems. 

Proof of this stems from observation that Wilms tumour tends to occur in the presence of common abnormalities of the genitourinary system such as undescended testes (testes failing to descend downwards into scrotum), horseshoe kidneys (fusion or joining of the two kidneys at one end, across the midline of the body) and abnormal opening on the penile shaft called hypospadias.

Wilms tumour affects approximately 10 children and adolescents per one million before age 15 years.

Commonly, one kidney is affected but in about 5-10 per cent of patients, both kidneys are affected at the same time or one after the other.

Wilms tumour appears to be relatively more common in Africa and least common in East Asia.

It is relatively more common in blacks than in whites. It is more seen in females than in males.

The median age at diagnosis of Wilms tumour is approximately 3.5 years.

Most common reason

The most common reason why people with this condition seek medical attention for this condition is abdominal swelling or mass.

The mass is painless and is usually felt accidentally by parents. In about 80 per cent of cases, abdominal swelling is the presenting complaint. 

However, less common symptoms that parents may notice include passage of bloody urine (haematuria) and recurrent infections along the pathway of voiding urine (urinary tract infections).

A few patients may bleed into their tumour and present with low blood pressure, anaemia, and fever.

Rarely patients with advanced disease may present with signs and symptoms related to the organ the tumour has spread to.

Unexplained weight loss with an abdominal mass in a child is a big clue for this cancer.

Medical examination

Examination by a doctor often reveals an abdominal mass large enough to be felt.

It is worth emphasising that once the mass is felt, parents should avoid frequent examination of it as it could lead to the rupture of the shield of the tumour and enhance its spread into other abdominal organs.

Once confirmed other associations such as abnormalities of the eyes and abnormal opening of the penile shaft in males, are looked for.

A safe and painless test that uses sound waves to make images of the kidneys, ureters, and bladder (Renal ultrasonography), is often the initial study because it does not expose children to the detrimental effects of radiation.

Abdominal computed tomography (CT) scanning, helps in determining the origin of the tumour, as well as the spread of the disease.

Abdominal magnetic resonance imaging (MRI) is reportedly the most sensitive imaging modality for determination of spread into the large blood vessels.

Treatment 

Fortunately, this is one of the tumours that if seen early can be completely cured. Treatment is multidisciplinary.

It involves a paediatric cancer specialist (oncologist), a paediatric surgeon as well as a radiotherapist.

Depending on the state, chemotherapy (using drugs to kill the cancer cells) is done. This reduces the size of the tumour and makes it very easy for surgery to remove the affected kidney.

Chemotherapy is continued after surgery is done to remove the affected kidney after which radiotherapy is done to take care of those that have spread to distant sites. Approximately 80-90 per cent of children with a diagnosis of Wilms tumour survive with therapy.

This contrasts with the rate of 10 per cent 50 years ago.

Survival rates

The addition of radiation therapy to surgery alone improves survival rates to approximately 40 per cent.

With the use of chemotherapy, survival rates have doubled. 

Surgery is done to remove the diseased kidney leaving the child with one functional kidney.

In almost all patients, the remaining kidney can compensate and maintain adequate kidney function.

The most important way to survive this cancer is for it to be diagnosed early, treatment instituted early and the long follow up regime strictly adhered to.

Refreshingly, this cancer can easily be treated at the Cancer Unit of the Children’s Block, Korle-Bu Teaching Hospital in Accra, as well as the Komfo Anokye Teaching Hospital in Kumasi.

Once again, the most important determining factor in the successful treatment of the childhood cancer remains early diagnosis.

Parents, please report any abnormal swellings you feel in the child’s abdomen for early diagnosis and treatment.

Wilms tumour is curable.

— Article written by: Dr Frank Owusu-Sekyere, supported by Dr Lily Gloria Tagoe and Dr Emmanuella Amoako from Korle Bu Teaching Hospital for World Child Cancer.