Wilms’ tumor, which is also known as Nephroblastoma, is the most common kidney tumor in children. It most often affects children between the ages of 2-5 years of age. Peak incidence of occurrence is between the ages of 2-3 years. This is a tumor that grows very rapidly and is typically large at diagnosis. The tumor will metastasize to the peri-renal tissue, the liver, diaphragm, lungs, abdominal muscles and the lymph nodes. Metastasis will occur through the bloodstream or by direct extension. Usually the tumor will occur in one of the kidneys, however, there are cases where both kidneys will have a tumor at the same time.
Etiology or Causes
The exact cause of Wilms’ tumor is not known. What we do know, however, is that cancer begins when there is an error in the DNA of cells. This leads to the cells growing and dividing uncontrollably, even in situations where normal cells would die. These rogue cells accumulate to form a tumor. There are cases where the DNA that causes the Wilms Tumor is passed from a parent to the child. However, those cases are rare.
Signs and Symptoms
The most obvious sign is a firm mass in the abdominal cavity. Other symptoms that might appear with this disorder is abdominal pain and swelling, constipation, vomiting, weight loss, loss of appetite, fever and difficulty breathing
To diagnose a Wilms Tumor, a physical examination would be your best starting point. Your doctor may order imaging test such as an ultrasound (sonogram), computerized tomography (CT scan), or an MRI (magnetic resonance imaging) in order to visualize the kidney and detect a tumor. If a tumor is discovered, your doctor might order a chest x-ray and a nuclear medicine bone scan to determine the extent of the tumor. This is necessary in order to stage the tumor and to offer some guidance in determining the best treatment modality for dealing with the tumor. A 24 hour urine collection could be ordered to measure the levels of HVA (homovanillic acid) and VMA (vanillylmandelic acid). In Neuroblastomas, the levels are elevated, but with Wilms tumor the levels are not elevated.
Staging of the Wilms Tumor
- Stage I: unilateral, limited to kidney, and can be resected from the kidney.
- Stage II: unilateral, with the tumor extending beyond the kidney, however, it can be resected from the kidney.
- Stage III: unilateral, with the tumor extending beyond the kidney and located in the lymph nodes, as well as, other structures in the abdominal cavity. The tumor may not be completely removed with surgery.
- Stage IV: unilateral with metastasis occurring in the liver, lung, bone or brain
- Stage V: bilateral kidney involvement
Treatment and Prevention
Surgical removal of the tumor and the affected kidney is the usual treatment. Some cases will require chemotherapy and radiation therapy. This will occur either before or after the surgery.
Radiation therapy uses high-energy beams, such as X-rays, to kill cancer cells.
Chemotherapy uses powerful drugs to kill cancer cells throughout the body. Chemotherapy treatment usually involves a combination of drugs that work together to kill cancer cells. Chemotherapy can be administered through a vein or taken in pill form.
Chemotherapy may be used before surgery to shrink tumors and make them easier to remove. Chemotherapy may be used after surgery to kill any cancer cells that may remain in the body.
Radiation therapy may be used after surgery to kill any cancer cells that weren’t removed during the operation. Radiation therapy may also be an option to control cancer that has spread to other areas of the body, depending on where the cancer has spread.
The survival rate is as high as 90%. However, there are potential complications which include metastasis. With radiation therapy, there is the potential for female sterility, bowel obstruction, pneumonia, scoliosis, and damage to the liver or kidneys.