Wilms Tumor

Wilms tumor and other kidney tumors are diseases in which malignant (cancer) cells are found in the kidney. In Wilms tumor, one or more tumors may be found in one or both kidneys. Clear Cell Sarcoma of the Kidney is a rare type of kidney cancer, in which the inside of the cells look clear when viewed under a microscope. Clear cell sarcoma can spread from the kidney to other organs, most commonly the bone, but also including the lungs, brain, and soft tissues of the body.


Staging of Wilms Tumor


For Wilms tumor, the stage is determined during the initial surgery and with the results from imaging tests.

The following stages are used for both favorable histology and anaplastic Wilms tumors:

Stage I

In stage I, the tumor was completely removed by surgery and all of the following are true:

  • Cancer was found only in the kidney and did not spread to blood vessels of the kidney.
  • The outer layer of the kidney did not break open.
  • The tumor did not break open.
  • A biopsy of the tumor was not done.
  • No cancer cells were found at the edges of the area where the tumor was removed.

Stage II

In stage II, the tumor was completely removed by surgery and no cancer cells were found at the edges of the area where the cancer was removed. Before the tumor was removed, one of the following was true:

  • Cancer had spread out of the kidney to nearby soft tissue.
  • Cancer had spread to blood vessels of the kidney.

Stage III

In stage III, cancer remains in the abdomen after surgery and at least one of the following is true:

  • Cancer spread to lymph nodes in the abdomen or pelvis (the part of the body between the hips).
  • Cancer spread to or through the surface of the peritoneum (the layer of tissue that lines the abdominal cavity and covers most organs in the abdomen).
  • Chemotherapy was given before surgery and a biopsy of the tumor was done during surgery to remove it.
  • The tumor broke open before or during surgery to remove it.
  • The tumor was removed in more than one piece.

Stage IV

In stage IV, cancer has spread through the blood to organs such as the lungs, liver, bone, or brain, or to lymph nodes outside of the abdomen and pelvis.

Stage V and those at high risk of developing Wilms tumor

In stage V, cancer cells are found in both kidneys when the disease is first diagnosed.

In addition to the stages, Wilms tumors are described by their histology.

The histology (how the cells look under a microscope) of the tumor affects the prognosis and the treatment of Wilms tumor. The histology may be favorable or anaplastic (unfavorable). Tumors with a favorable histology have a better prognosis and respond better to chemotherapy than those with anaplastic histology. Tumor cells that are anaplastic divide rapidly and do not look like the type of cells they came from. Anaplastic tumors are harder to treat with chemotherapy than other Wilms tumors at the same stage.


Treatment of Wilms Tumor


Wilms tumor and other childhood kidney tumors are usually diagnosed and removed in surgery.

Once a kidney tumor is found, surgery is done to find out whether or not the tumor is cancer. If the tumor is only in the kidney, the surgeon will remove the whole kidney (nephrectomy). If there are tumors in both kidneys or if the tumor has spread outside the kidney, a piece of the tumor will be removed. In any case, a sample of tissue from the tumor is sent to a pathologist, who looks at it under a microscope to check for signs of cancer.

Four types of standard treatment are used:

  • Surgery
  • Radiation therapy
  • Chemotherapy
  • Biologic therapy


New types of treatment are being tested in clinical trials.


For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment. Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment. Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.

Search for clinical trials in Georgia.

Adapted from the National Cancer Institute's PDQ Database: http://www.cancer.gov/cancertopics/pdq/treatment/wilms/Patient/page1. (Accessed July 2016)