Wilms tumor

Synonyms in a broader sense

Nephroblastoma, tumor, cancerThe Wilms tumor is a malignant mixed tumor, which consists of embryonic adenosarcoma parts with rhabdomyoblastic and heteroblastic, as well as differently differentiated parts of renal tissue and is usually detectable in one or both kidneys. At times, the tumor may already fill large parts of the abdominal cavity. The size is not necessarily a prognostic criterion, since tumors of this size may still be easily removed surgically.

Based on various studies, a classification, the so-called SIOP classification (International Society of Paediatric Oncology), has been developed. If the tumor is in stage 1, it is restricted to one kidney and the capsule is intact. In stage 2, the tumor already exceeds the kidney capsule and grows into fatty tissue or blood vessels, but is still completely removable by surgery.

If a peritoneal metastasis is already detectable and surgery is not possible because of the invasion of vital organs, this is called stage 3. Stage 4 is reached when distant metastases are already detectable in the lung, liver, bone or brain. A bilateral kidney infestation would then be called stage 5.

The causes of Wilms’ tumor are still largely unknown today. Only a genetic connection could be found. Carriers with a defective gene 11p13 or 11p15 are particularly at risk of developing nephroblastoma or a so-called WAGR syndrome.

In addition to the actual Wilms tumor, this syndrome also includes a defective iris formation of the eyes (aniridia) and reduced or delayed growth of the child. All in all, Wilms’ tumor is a rare tumor that occurs about 70-100 times a year in Germany (0.9/100. 000/year).

However, it is the most common tumor in children and accounts for 6-8% of all childhood tumors. Children between the ages of 2-5 years are particularly frequently affected. After the age of 10, nephroblastoma can only rarely be diagnosed.

In 5% of cases, tumorous changes can be observed on both kidneys of the child. Boys are statistically more frequently affected than girls. The symptoms of Wilms’ tumor are mostly quite unspecific.

Children often suffer from loss of appetite, vomiting, abdominal pain and fever. Less frequently, bloody urine (hematuria) occurs, since this already means that the tumor has invaded the urinary tract. Parents may already be able to palpate a bulge in the abdomen, which then corresponds to the extent of the tumor.

Sometimes children also suffer from constipation or diarrhoea, weight loss, paleness, urinary tract infections or high blood pressure. The therapy to be aimed at is primarily the surgical removal of the tumor or the organs (if possible) that are affected by the tumor. A complete removal of the tumor is usually only possible in stages 1 and 2 (see above).

If a tumor is in stage 1, treatment with a chemotherapeutic agent would first be started before the operation in order to reduce the tumor as much as possible. After surgical removal of the tumor and the affected kidney (nephrectomy), so-called postoperative chemotherapy would then be performed to kill any tumor cells that are still present and have not been surgically removed. In stage 2, in addition to a tumor-reducing chemotherapy prior to surgery (preoperative-neoadjuvant chemotherapy) and a tumor and kidney removal, chemotherapy with parallel radiation would be performed.

In stages 3 and 4, radiation therapy prior to surgery would be required in addition to tumor-reducing chemotherapy. Once the findings have become so small that the operation is also operable, the tumor and kidney would be removed and followed by chemotherapy with subsequent radiation. The treatment to reduce the size of the tumor is also known as “down staging”.

The chemotherapeutic agent used is usually vincristine with adriamycin (possibly plus actinomycin D plus ifosfamide/cyclophosphamide). Chemotherapy is continued for 5-10 months after the operation. The operation takes place in the following steps: first, a centrally positioned abdominal incision is made.

The kidney is then separated from the renal bed by clamping off the important renal vessels. Any metastases that may have been detected are also removed.The lymph nodes along the main artery (aorta) and the vena cava are also removed prophylactically, even if there is no evidence of tumor infestation at this site. If both kidneys are affected, the kidney with the larger finding is completely removed, the other kidney is then operated on to preserve the organ.

Only the tumor is removed from its localization. In addition to the known complications of chemotherapy (hair loss, nausea, vomiting, fatigue, inflammation of the mucous membranes, etc. ), irradiation can also lead to pelvic deformities, pulmonary fibrosis and myocardial damage.

A complication after surgery is the so-called tumor thrombus in the vena cava, which occurs in 5% of cases. Since the mechanism of Wilms’ tumor development is largely unknown, prophylactic measures are not known. Although Wilms’ tumor (nephroblastoma) is a rare tumor, it is the most common tumor among children.

It is a malignant mixed tumor of different tissues, but usually originates from one or both kidneys. In addition to unspecific complaints such as nausea, vomiting, weight loss, a palpable mass or bloody urine should remind the patient of the diagnosis nephroblastoma. The spread of the tumor is classified according to the so-called SIOP classification.

Thus, stage 1 and 2 are locally limited and usually operable, while in stage 3 and 4 the tumor has already spread in the body and cannot be operated on directly. In addition to questioning the patient, the physician should also perform palpation of the abdomen, an ultrasound, a urine examination, possibly a CT scan, and x-rays for so-called tumor staging (spread of the tumor). Tumors of all stages must first be pretreated with chemotherapy and after surgical removal of the tumor and kidney post-treatment.

In some stages, additional radiation may be necessary after or before and after surgery. The administration of various chemotherapy substances should be continued 5-10 months after the surgical procedure. At over 75%, the healing rate of Wilms’ tumor is quite good, although this depends on the stage and ranges from 100% (stage 1) to 50-60% (stages 3 and 4). Continue to topic: Wilms tumor prognosis