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Wilms' tumor

Wilms Tumor; Nephroblastoma

Overview

Wilms' tumor or nephroblastoma is a tumor of the kidneys that typically occurs in children about 3 years old, rarely in children older than 15 years of age and adults. Its common name is an eponym, referring to Dr. Max Wilms, the German surgeon (1867–1918) who first described this kind of tumor. Approximately, 500 cases are diagnosed in the United States annually. The majority of cases (75%) occur in otherwise normal children; a minority (25%) is associated with other developmental abnormalities. Moreover, Wilms' tumor is relatively more common in blacks than in whites and is rare in East Asians. Estimates suggest 6-9 cases per million person years in whites, 3-4 cases per million person years in East Asians and more than 10 cases per million person years among black populations.  The Wilms' tumor is highly responsive to treatment, with about 90% of patients surviving at least five years.

Symptoms - Wilms' tumor

Symptoms may include any of the following:
  • Fever
  • Constipation
  • Abnormal urine color
  • General discomfort or uneasiness
  • High blood pressure
  • Nausea and vomiting
  • A painless, palpable abdominal mass
  • Loss of appetite
  • Abdominal pain
  • Blood in the urine
  • Sweating (at night)
  • Increased growth on only one side of the body
Note: Contact your medical practitioner, if your child develops any of the above symptoms of Wilms' Tumour and also if your child is being treated for this condition and symptoms get worse, mainly cough, chest pain, weight loss, or persistent fevers.

Causes - Wilms' tumor

The exact cause of Wilms' tumor in children is still unknown. However, the following factors may increase the risk of developing Wilms' Tumor:

  • Race - Black children have a slightly higher risk of developing Wilms' tumor than do children of other races. Children of Asian descent appear to have a lower risk than do children of other races.
  • Family history - If someone in your child's family has had Wilms' tumor, then your child has an increased risk of developing the disease. It is more common among some siblings and twins, which suggests a possible genetic cause.
  • Abnormalities at birth - Children with certain abnormalities present at birth have an increased risk of developing Wilms' Tumor e.g. aniridia (partially formed/absence of iris); hemihypertrophy (condition where one side of the body is noticeably larger than the other side); cryptorchidism (undescended testicles); hypospadias (urethral is not at the tip of the penis, but is on the underside)
  • Pre-existing rare syndrome(s) - Wilms' Tumor can occur as part of rare syndromes, including WAGR syndrome, Denys-Drash syndrome and Beckwith-Wiedemann syndrome.

Prevention - Wilms' tumor

Although the exact cause of Wilms' Tumor is still unknown, ultrasound screening are suggested for children with a known high risk for Wilms' Tumor.

Diagnosis - Wilms' tumor

Diagnostic tests include:

  • Abdominal ultrasound
  • Abdominal x-ray
  • BUN
  • Chest x-ray
  • Complete blood count (CBC), may show anemia
  • Creatinine
  • Creatinine clearance
  • CT scan of the abdomen
  • Intravenous pyelogram
  • Urinalysis

A physical examination may show an abdominal mass. High blood pressure may also be present.

Once the diagnosis of Wilms' tumor is confirmed, the stage of the cancer is determined. A chest X-ray, chest CT scan and bone scan are used to determine whether the cancer has spread beyond the kidneys. 

The stages of Wilms' tumor are:

  • Stage I. The cancer is found only in one kidney and generally can be completely removed with surgery.
  • Stage II. The cancer has spread to the tissues and structures near the affected kidney, such as fat or blood vessels, but it can still be completely removed by surgery.
  • Stage III. The cancer has spread beyond the kidney area to nearby lymph nodes or other structures within the abdomen, and it may not be completely removed by surgery.
  • Stage IV. The cancer has spread to distant structures, such as the lungs, liver, bones or brain.
  • Stage V. Cancer cells are found in both kidneys.

Prognosis - Wilms' tumor

Approximately 80-90% of children with a diagnosis of Wilms' Tumour survive with the appropriate treatment. Patients who have tumors with favorable histology, have an overall survival rate of at least 80% at 4 years after the initial diagnosis, even in patients with stage IV disease.

Treatment - Wilms' tumor

Treatment for Wilms' tumor usually involves surgery and chemotherapy, but treatments may vary by the stage of the cancer. Surgery is also used to confirm the diagnosis, since the tissue removed during surgery is sent to a laboratory to determine whether it is cancerous.

  • Surgery for Wilms' tumor may include - 

Removing part of the affected kidney: Partial nephrectomy involves removal of the tumor and part of the kidney tissue surrounding it. Partial nephrectomy may be an option if your child's cancer is very small or if your child has only one functioning kidney.

Removing the affected kidney and surrounding tissue: In a radical nephrectomy, doctors remove the kidney and surrounding tissues, including the ureter and adrenal gland. Neighboring lymph nodes also may be removed. The remaining kidney can increase its capacity and take over the entire job of filtering the blood.

Removing all or part of both kidney: If your child's cancer affects both kidneys, the surgeon works to remove as much cancer as possible from both kidneys. In a small number of cases, this may mean removing both kidneys, which means your child would then undergo kidney dialysis. A kidney transplant may be an option so that your child will no longer need dialysis.

  • Chemotherapy - This treatment 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; after surgery to kill any cancer cells that may remain in the body. Chemotherapy may also be an option for children whose cancers are too advanced to be removed completely with surgery.

For children who have cancer in both kidneys, chemotherapy is administered before surgery. This may make it more likely that surgeons can save at least one kidney in order to preserve kidney function.

  • Radiation therapy - This treatment uses high-energy beams, such as X-rays, to kill cancer cells. During radiation therapy, your child is positioned on a table and a large machine moves around your child, precisely aiming energy beams at the cancer. Possible side effects include nausea, diarrhoea, fatigue and sunburn-like skin irritation.

Radiation therapy may be used after surgery to kill any cancer cells that weren't removed during the surgery. 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.

  • Novel cancer treatments - Your child's doctor may recommend participating in a clinical trial. These research studies allow your child a chance at the latest cancer treatments, but a cure can not be guaranteed. Discuss the benefits and risks of clinical trial with your medical practitioner.

Resources - Wilms' tumor

NIH, The Mayo Clinic, Medline Plus

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