Wilms’ tumor – kidney cancer in children

Wilms' tumor - kidney cancer in children

When the German surgeon Max Wilms described a specific type of kidney cancer in children in his work “Die Mischgewuelste”, published in 1899, he did not yet know that it would later be named after him. He was probably even less able to imagine that the tumour, which was inevitably fatal at the time, can usually be defeated with today’s therapy. A cancer diagnosis is always terrifying at first, especially when it comes out of the blue and affects a child. But in the case of Wilms’ tumour (or nephroblastoma), those affected can hope, at least from the start: today, it is one of the types of cancer with the best chances of recovery.

Causes: How does Wilms’ tumour develop?

It has been known that nephroblastoma develops from various essential embryo tissues (hence the term “mixed tumour”), generally recedes by birth or develops into the final tissue. Depending on the stage of development of the tumour cells and the tissue they originate from, the tumour can appear very different and multifaceted under the microscope.

It is not yet clear exactly how the germ tissue in parts of the kidney does not develop normally. However, we now know that genes with the ominous names WT1 and WT2 on chromosome 11 and probably others play a role. What also speaks for a congenital component is that other malformations are not uncommon to be present simultaneously, e.g., the absence of an eye lens, gigantism on only one side of the body or a horseshoe kidney.


Frequency of Wilms’ tumour

Although Wilms’ tumour is the most common form of kidney cancer in children, it is rare, affecting 1 in 100,000 children. This corresponds to an annual incidence rate of 110 children in Germany. A good third of those affected are between 1 and 5 years old, and 16% are infants. Both kidneys are affected in 5% of cases.

What are the symptoms of the disease?

What is treacherous is that the tumour usually does not cause any symptoms for a long time – in about 10%, the diagnosis is an incidental finding during a routine examination. By far, the most common symptom is the increase in abdominal circumference, which is often initially misinterpreted as bloating or attributed to a good nutritional status. Indigestion, blood in the urine or abdominal pain are less common.


Nephroblastoma: how is the diagnosis made?

blood test only indicates an inflammatory process in the late stages. In addition, another type of tumour (neuroblastoma) can be ruled out if necessary.

The most essential diagnostic tools are imaging procedures, particularly ultrasound and magnetic resonance imaging. This can then be used to determine the size and spread and to see whether other organs are affected. An X-ray is also taken since the tumour particularly often spreads to the lungs. The function of the kidneys is assessed with scintigraphy.

Further examinations depend on the tumour and the therapy. Since nephroblastoma can be diagnosed quite reliably with these means, tissue removal (fine needle biopsy), which carries the risk of the tumour spreading into the abdominal cavity, is only necessary in very few exceptional cases. Depending on whether the tumour is limited to only one kidney, has grown into the surrounding tissue, has spread metastases, has affected both kidneys and can be removed surgically, it is assigned to one of five stages, which differ not only in treatment but also in treatment also differ in the prognosis.

What treatment is available for Wilms tumour?

Treatment is a combination of Chemotherapy (as tablets or injected into the vein or muscle), surgery and – in some cases – Radiation. It depends on the type of tumour, its spread (staging) and the child’s age.

There are two primary treatment guidelines worldwide. They differ in that, in some cases, Chemotherapy is carried out after an operation, and in others, it is carried out beforehand. The second approach is common in Germany.

With Chemotherapy, before the operation (preoperative), the tumour can be reduced in size and thus moved into a group with a better prognosis. In addition, the risk of tumour rupture with the spread of cancer cells or bleeding during surgery is reduced. The duration of preoperative Chemotherapy ranges from 4 to 40 weeks, depending on the tumour.

During the operation, the affected kidney can be removed with or without surrounding tissue and lymph nodes or, for example, if only one kidney is left, the tumour must be peeled out. Whether additional radiation or further Chemotherapy is necessary depends on the surgical findings and what the removed tissue looks like under the microscope.

What is the course and prognosis?

With today’s therapy methods, around 90% of all those affected can be cured in the long term. In each case, the prognosis depends on the stage of the tumour and its tissue types and composition.

Complications can arise with each method, for example:

  • Bleeding and Inflammation during the operation
  • blockage of the liver veins, hearing impairment, anaemia or heart disease during Chemotherapy
  • Impairment of lung function, hardening of connective tissue or cancer diseases (years later) as a result of the radiation

Recurrence, i.e. a return of the treated cancer, and complications occur most frequently in the first two years after the end of therapy. For this reason, the children must be checked very closely during this time – at the beginning at intervals of a few weeks, later months. In addition to the doctor’s consultation and the clinical examination, this also includes the ultrasound of the abdomen, the X-ray of the lungs and the determination of blood and urine values.

Depending on the type of tumour and therapy, bone scintigraphy, ECG cardiac ultrasound, and hearing tests can be added.

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