Kidney (renal) tumours are very rare in children, and most – about 75% – occur in children under the age of 5. Tumours of the kidney are often not diagnosed until they are fairly large and cause pain or swelling. They can spread to the lungs, liver or nearby lymph nodes. Kidney tumours are typically unilateral (only in one kidney), but can be found bilaterally (occurring in both kidneys).
Typical symptoms of tumours of the kidney are pain, swelling or a lump in the abdomen and blood in the urine. If a kidney tumour is found wholly contained within one kidney, the typical surgery is a nephrectomy – removal of the entire kidney. If the tumour has spread outside the kidney or is bilateral, portions will be removed.
Types of Childhood Kidney Cancers
A variety of tumours make up the spectrum of childhood kidney cancers and other rare childhood kidney cancers include:
The most common paediatric kidney cancer is Wilms’ tumour – accounting for 95% of childhood kidney cancers – we will discuss Wilms’ tumour at length in a separate article.
Anaplastic Sarcoma – Anaplastic sarcoma of the kidney is a rare tumor that is most common in children or adolescents younger than 15 years of age – it often spreads to the lungs, liver, or bones. Anaplastic sarcoma may be an inherited condition.
Clear Cell Sarcoma of the kidney is the second most common type of kidney tumour in children – it is most common in infants and young children aged 1-4 years. It affects the supporting tissues in the kidney, and may spread to the lungs, bones, brain, and soft tissue. It also appears to have a higher relapse rate – it may recur (come back) up to 14 years after treatment, and it often recurs in the brain or lung.
Cystic Partially Differentiated Nephroblastoma is a very rare type of Wilms’ tumour made up of cysts.
Desmoplastic Small Round Cell Tumour of the kidney is a rare soft tissue sarcoma that most often affects boys. It may develop and spread in the abdomen, pelvis or tissues around the testes. It may also spread to the lungs and other parts of the body.
Ewing Sarcoma (neuroepithelial tumour) of the kidney is rare and usually occurs in adolescents. These tumours grow and spread to other parts of the body very quickly. At diagnosis, these tumours have often spread to the outer layer of the kidney, the veins of the kidney, and to other parts of the body.
Mesoblastic Nephroma is a non-cancerous (benign) tumour of the kidney that is usually diagnosed within the first 3 months of life, sometimes even via an in utero ultrasound. It seems to occur more frequently in males than females and can usually be cured with surgery alone.
Multilocular Cystic Nephromas are non-cancerous (benign) tumours made up of cysts, which can occur in one or both kidneys. They are most common in infants, young children, and adult women. Children with this type of tumour could also have pleuropulmonary blastomas in the lungs. Multilocular cystic nephroma may be an inherited condition.
Renal Cell Carcinoma (RCC) (also called Renal Adenocarcinoma or Hypernephroma) is the most common form of kidney cancer among adults, but it is rare in children younger than 15 – it is much more common in adolescents between 15 and 19 years old. It can spread to the lungs, bones, liver, and lymph nodes. Renal cell carcinoma in children is sometimes associated with genetic conditions, such as von Hippel-Lindau disease, tuberous sclerosis, neuroblastoma and/or sickle cell disease.
Rhabdoid Tumour of the kidney is a type of cancer that occurs mostly in infants and very young children, typically under the age of 1. At diagnosis, children may have fever, blood in the urine, and advanced cancer. Rhabdoid tumours grow and spread quickly, often to the lungs and brain.
Synovial Sarcoma is most common in adolescents and grows and spreads quickly.
Tests for Childhood Kidney Cancer
The following tests and investigations may be used for the detection of childhood kidney cancer, including Wilms’ Tumour:
Physical Examination of the body to check your child’s general health and to look for any lumps or swellings. A medical history of your child’s past illnesses and treatments will also be taken. This will most likely take place at your family doctor’s surgery and may be repeated at the hospital if your child is referred for further tests.
Blood and Urine Samples will be taken by your doctor to check your child’s kidney function and general health.
Abdominal Ultrasound Scan and a CT Scan are often done at the hospital to help diagnose the tumour and to assess its growth and spread. Occasionally scans of the chest and liver may also be taken to check the spread of the disease. The information obtained from these scans is used to stage the progress of the disease.
Biopsy of the tumour is taken from most children to confirm the diagnosis made using the scans. There are two types of biopsy;
- during a needle biopsy cells are removed from the tumour using a needle inserted through the skin and into the tumour under local anaesthetic.
- During a tissue biopsy a piece of tumour is removed during a small operation under general anaesthetic.
Sometimes, the surgeon will remove the entire tumour during this operation. The cell and tissue samples are sent to a pathologist, who examines them under a microscope to confirm the tumour as having favourable or unfavourable histology.
Treatment of Kidney Tumours
The main treatment for all renal tumours in children is surgery to remove the tumour. For most patients, a surgery called radical nephrectomy is done.
In this surgery, the tumour and whole kidney are removed. The doctor will look at the nearby lymph nodes and the liver to see if cancer has spread. It is critical to know if the tumour is only in the kidneys.
After surgery, some patients may receive chemotherapy and/or radiation therapy.
Each child will receive a dose of chemotherapy drugs based on their personal health. Generally, children who have the whole tumour removed get chemo for 6 months.
- With surgery alone, the survival rate is only 25%
- With chemotherapy, the survival rate is nearly 90%
If the tumour is still present or it has spread, the child will be given a different type of chemotherapy drug.
Radiation therapy uses special x-rays to shrink tumours and may be used, depending on where the cancer has spread. Together with the other treatments, radiation can improve survival. There is some risk of side effects.
Mesoblastic and multilocular cystic nephromas are benign tumours that can be cured via surgery alone – no other treatment is required.