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Wilms tumour

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Staging Wilms tumour

Staging is a way of describing or classifying a cancer based on the extent, or amount, of cancer in the body. The National Wilms Tumor Study Group (NWTSG) is an American group that developed a staging system for Wilms tumour. This system is based on how much cancer can be removed with surgery and the extent of disease before chemotherapy. Pediatric oncologists at Canadian hospitals participate in an organization called the Children’s Oncology Group (COG). COG uses the NWTSG staging system.

Stage grouping for Wilms tumour

In the NWTSG staging system, each stage is given a number from 1 to 5, usually as a Roman numeral (I, II, III, IV or V). Generally, the higher the number, the further the cancer has progressed. Your healthcare team uses the stage grouping to plan treatment and estimate prognosis.

When describing the stage, doctors look at where the tumour is in the kidney. They also consider if there are cancer cells at the edge of the tissue removed by surgery. If cancer cells are not present, it is called negative surgical margins. If cancer cells are present, it is called positive surgical margins. Doctors may also use the terms regional and distant. Regional means close to or around the kidney. Distant means in a part of the body farther from the kidney.

Stage I

About 40%-45% of Wilms tumours are stage I, which is defined as follows.

StageExplanation

stage I

The tumour is confined to the kidney and is completely removed with surgery.

The tumour has not grown through the renal capsule (the tissue layer surrounding the kidney).

The cancer has not spread to the renal sinus vessels (renal artery and renal vein).

The tumour had not burst (ruptured) or was not biopsied before it was removed.

There are no cancer cells at the edge of the tissue removed by surgery (referred to as negative surgical margins).

Stage II

About 20%-25% of Wilms tumours are stage II, which is defined as follows.

StageExplanation

stage II

The tumour has started to spread to nearby structures beyond the kidney, but is completely removed with surgery.

The surgical margins are negative.

At least one of the following has occurred:

  • The tumour has grown through the renal capsule.
  • The tumour invaded the renal sinus vessels.

Stage III

About 20%-25% of Wilms tumours are stage III, which is defined as follows.

StageExplanation

stage III

The tumour has spread beyond the kidney and is not completely removed with surgery.

The tumour has not spread outside the abdomen.

At least one of the following has occurred:

  • The cancer has spread to nearby lymph nodes in the abdomen or pelvis (regional lymph node metastases), but not to more distant lymph nodes.
  • The tumour has grown through to the surface of the peritoneum (the lining of the abdominal cavity).
  • Cancer cells have broken away from the main tumour and have started new tumours (called tumour implants) on the surface of the peritoneum.
  • Cancer cells are found at the edge of the tissue removed by surgery (positive margins), indicating that some of the cancer still remains after surgery.
  • The tumour has invaded nearby vital structures and cannot be removed completely.
  • The tumour burst (ruptured) or spilled into the abdominal cavity before or during surgery.
  • The tumour is treated with chemotherapy, with or without a biopsy, before surgical removal.
  • The tumour is removed in more than one piece (for example, a tumour inside the renal vein is removed separately).

Stage IV

About 10% of Wilms tumours are stage IV, which is defined as follows.

StageExplanation

stage IV

The tumour has spread, or metastasized, to other parts of the body, such as to lymph nodes outside of the abdomen and pelvis or to the lungs, liver, bone or brain.

Stage V

About 5% of Wilms tumours are stage V, which is defined as follows.

StageExplanation

stage V

There are tumours in both kidneys at diagnosis (bilateral Wilms tumour).

Recurrent Wilms tumour

Recurrent Wilms tumour means that the cancer has come back after it has been treated. If it comes back in the same place that the cancer first started, it’s called local recurrence. If it comes back in tissues or lymph nodes close to the primary tumour, it’s called regional recurrence. It can also recur in another part of the body, which is called metastatic Wilms tumour.

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Catherine Coulson Slowly, it dawned on me that I, too, could be a survivor

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