Wilms' tumor

Disease information

Overview
Causes
and Symptoms
Treatment

Overview

Wilms' tumor, also known as nephroblastoma, is a type of cancer primarily found in the kidneys. Among children, it is the second most common abdominal cancer following neuroblastoma. Your kidneys, which are tucked away in the back of your abdomen on either side of your spine, have a vital job. They filter out waste products from your body and create urine.

These bean-shaped organs do more than just waste management. They balance your body's fluids and electrolytes, maintain acid-base equilibrium, and produce essential hormones and vitamins that help regulate other bodily functions. This includes controlling your blood pressure, hormone secretion, calcium metabolism, vitamin production, and even the production of red blood cells, which can be related to anemia. A Wilms' tumor is often discovered in otherwise healthy children when a mass is unexpectedly felt in their abdomen.

In the United States, Wilms' tumor represents 5-7% of all child cancer cases. In Korea, approximately 36 cases are reported each year. The incidence of Wilms' tumor is similar in both boys and girls, and it is extremely rare in newborns. Most commonly, this tumor appears around the ages of 2-3, with over 80% of all cases diagnosed before a child reaches the age of 5. Along with neuroblastoma, it is one of the most frequent pediatric abdominal cancers. It is important to distinguish Wilms' tumor from other conditions such as clear cell sarcoma of the kidney, rhabdomyosarcoma, and lymphoma among others.

Causes and Symptoms

Wilms' tumor typically develops without any known cause, but about 1-2% of cases have a family history. These familial cases usually get diagnosed at a younger age and often involve tumors in both kidneys. The WT1 gene, also known as the Wilms tumor suppressor gene on chromosome 11, has a significant link to the development of this disease. Other genetic irregularities on chromosomes 16 and 1 have also been found to contribute to Wilms' tumor. The WT1 gene is crucial in the formation of kidneys and regulates the growth, differentiation, and programmed death of cells.

Most children with Wilms' tumor don't show any specific symptoms. It's often an abdominal or side mass that prompts parents to take their child to a doctor. Some kids might have abdominal pain, which could signal the risk of the tumor bursting and causing bleeding. This situation may need surgical intervention. The mass in the abdomen is usually quite large, doesn't hurt when touched, and doesn't move when the child breathes.

Fewer than 10% of children with Wilms' tumor may show whole-body symptoms due to the tumor pressing on other tissues or entering the bloodstream. Common symptoms include abdominal pain, vomiting, loss of appetite, high blood pressure, and occasionally blood in the urine. It's also important to check for any birth defects that might be associated with Wilms' tumor. These can include conditions like hypospadias (a condition where the opening of the urethra is on the underside of the penis), undescended testes, one side of the body growing larger than the other (as seen in Beckwith-Wiedemann syndrome), or lack of the colored part of the eye (aniridia), which can occur alongside Wilms' tumor.

Treatment

Surgery

Surgery is the primary treatment option for Wilms' tumor. The goal of the surgical procedure is to completely remove the tumor without causing it to break open. Typically, the surgical procedure used is called a radical nephrectomy, which involves removing the kidney containing the tumor. Sometimes, if the tumor is too large and surgery may be challenging, we may use chemotherapy first. This treatment can help to shrink the tumor and make the surgery easier to perform. After the surgery, we often administer additional chemotherapy to ensure any remaining cancer cells are destroyed. This approach helps to prevent the tumor from coming back and increases the chances of successful treatment.

Chemotherapy

The main purpose of surgery in treating Wilms' tumor is to determine the stage of the disease. Once the surgery is completed, chemotherapy is customized according to the specific characteristics of the tumor. For patients with Stage I and II Wilms' tumor, treatment usually involves drugs like actinomycin-D and vincristine. This approach is often enough and has a very high success rate, with cure rates between 85 to 90%.

For those with Stage III and IV of the disease, the treatment plan can vary. It depends on the specific characteristics of the tumor cells. In most cases, localized radiation therapy to the abdomen is required. This treatment plan includes a variety of chemotherapy regimens. For patients diagnosed with Stage V Wilms' tumor, the treatment typically starts with chemotherapy. This initial treatment helps to reduce the size of the tumors in both kidneys. After the tumors have shrunk, a partial nephrectomy, which is the surgical removal of part of the kidney, is usually performed. Depending on the results from the tissue analysis, additional chemotherapy may be given.