Kidney cancer in children

Kidney cancer is a rare illness among children as it only makes up 7 percent of all childhood cancers. Among the subtypes of kidney cancer in children, Wilms’ tumour is the most prevalent form. These usually afflict children under the age of 5. They are caused by mutations in kidney cells that emerge typically after birth and commonly affect only one kidney. Nonetheless, it can be discovered in both kidneys in 5 to 7 percent of instances, and most of the cases are sporadic.

Most juvenile malignancies have unclear causes. Nonetheless, Wilms’s tumour is often part of a group of symptoms known as WAGR syndrome. The acronym reflects the main diseases associated with the syndrome—W for Wilms’ tumour, A for aniridia, G for genitourinary anomalies and R for intellectual disability (previously called mental retardation). People with WAGR syndrome may also develop cataracts and glaucoma on top of aniridia. WAGR syndrome patients have a 45 to 60 percent risk of developing Wilms’ tumour.

  

Symptoms

1.    Painless swelling in the abdomen. The tumour may cause the abdomen to swell, causing discomfort.

2.    Haematuria or presence of blood in urine.

3.    Hypertension. Wilms’ tumour can cause high blood pressure.

4.    Fever.

5.    Children may experience a loss of appetite, resulting in weight loss.

6.    Pain in the abdomen especially if there is bleeding within the tumour causing a sudden increase in size of the mass.

7.     Generally feeling unwell.

8.     Cough and shortness of breath if the tumour has spread to the lungs.

 

Most times, the kidney is effectively non-functional upon presentation to a doctor as the tumour would have grown to a size that is causing major discomfort to the child. The child will likely need to undergo a blood test to look at the baseline health, blood and kidney function levels. Radiological examinations are likely necessary—ultrasound of the abdomen and CT scan to further define the tumour, and for staging. (Table 1)

Table 1: Stages of kidney tumour

Stage	Description
I	Tumour is within the kidney
II	Tumour is still within the kidney but has involved surrounding fatty tissue and blood vessels. Tumour can still be completely removed.
III	Very large tumours that have crossed the midline of the body
IV	Tumour has spread to distant sites usually the lungs, liver or bone
V	Tumour involving both kidneys

Treatment options
Depending on the tumour staging, the child may need to undergo surgery to remove the affected kidney. Surgery is usually done immediately for stages I or II but is delayed for stage III disease. Surgery is the mainstay of treatment, and all children with kidney cancer will likely undergo surgery. Partial nephrectomy or renal-sparing surgery is reserved for bilateral tumours.

Chemotherapy is given either as adjuvant (after surgery to kill off the remaining cancer cells in stage I and II tumours); or neoadjuvant (before surgery to reduce the tumour size and to kill off cells that may have spread from the main site). Neoadjuvant therapy is usually indicated in stage III patients as the tumour is too large and must be shrunk to allow for safe surgery thereafter.

Radiotherapy may be necessary in some patients depending on what the tumour looks like microscopically, how far it has spread outside the kidney or if it has spread to distant organs such as the lungs. It is also indicated when the tumour has not completely resolved with chemotherapy.

The prognosis for Wilms’ tumour is good. The cure rate for stage 1 Wilms’ tumour is 95 percent. As for stages II to IV, if there are no unfavourable histological features, a 4-year survival rate of 90 percent can be expected.

Is it possible to prevent kidney cancer in children?

As the cause is largely unknown, it is difficult to have any preventive measure. However, for children with abnormalities such as WAGR, abdominal ultrasound surveillance is performed periodically, usually every 6 months, to detect the possible development of Wilms’ tumour. Additionally, parents should be advised to be more vigilant regarding symptoms and signs. It is the healthcare professional’s responsibility to educate the public on the most frequent symptoms and indications of childhood cancer.

While it is likely unpreventable, there are warning signs to look out for to detect kidney cancers early. These include:
1. Advising parents to look out for lumps when they are dressing or bathing their children. Sometimes one side of the stomach is noticeably larger than the other.

2. Haematuria or blood in the urine. This means there is bleeding from the kidney, prostate, or bladder. 

3. Loss of appetite and weight loss. Tumours that form in the left kidney can compress the stomach as it grows bigger leading to a sense of fullness when the child eats, hence the reduction in weight.

4. Babies born with big birth weight and hemihyperplasia, an asymmetric growth of single or multiple organs or regions of the body, tend to develop kidney cancer and should be followed up regularly.

5. Cautioning pregnant women and breastfeeding mothers to be careful when taking supplements as they may be metabolized and passed on to the child. Some may be deleterious to the child’s liver and kidneys.