Wilms' tumor staging
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Shanshan Cen, M.D. [2]
Overview
There are 5 stages of wilms' tumor based on both the results of the imaging studies and the surgical and pathologic findings at nephrectomy.
Staging
- Staging of wilms tumor is done based upon:
- Extent of tumor anatomically.
- It is not done on the basis of its genetics, histology or molecular markers.
- Extensive disease and worse prognosis is denoted by a higher stage.
- Patients suffering from a higher stage tumor get more aggressive treatment modalities.
- The staging systems that are currently used are:[1]
- National Wilms Tumor Study (NWTS) system.
- International Society of Pediatric Oncology (SIOP) system.
NWTS system
- This system is used throughout United States and Canada.
- It is based on the evaluations done during surgery before the administration of surgery.
- According to this system wilms tumor is divided into following stages.[2]
- Stage 1
- Tumor is limited only to the kidney.
- When the tumor is resected the capsule is intact.
- Resected tumor shows no evidence of involvement of renal sinus vessel.
- Stage 2
- Tumor is extended beyond the kidney, but can be resected completely.
- Tumor margins go beyond the renal capsule.
- It extends into the renal capsule, soft tissues and blood vessels beyond the renal parenchyma.
- But all this is within the margins of the resected tumor.
- Stage 3
- Complete tumor cannot be resected.
- The remaining tumor is confined within the abdomen.
- Residual tumor remaining within abdomen includes :
- Regional lymph nodes
- Peritoneal surface
- Incomplete resection of tumor
- Tumor spillage
- Stage 4
- In stage 4 either hematogenous metastasis are present or lymph nodes are affected beyond the abdominopelvic region.
- Hematogenous metastasis include sites like:
- Lung
- Liver
- Bone
- Brain
- Stage 5
- When wilms tumor is diagnosed, bilateral renal involvement is seen.
- Each kidney has to be staged separately.
- Stage 1
SIOP staging
- This system is followed in Europe.
- This system is based on the surgical evaluation done after the size of the tumor is reduced after chemotherapy.
- According to this system wilms tumor is divided into following stages.
- Stage 1
- Tumor is limited only to the kidney.
- If the tumor extends beyond the kidney, a fibrous pseudocapsule surrounds it.
- Tumor can be found in the pelvic system but should not involve ureter walls.
- Stage 2
- Tumor is extended beyond the kidney, but can be resected completely.
- After resection there is no evidence beyond the resection margins.
- Stage 3
- Stage 1
- ●Stage 2 – Tumor extends beyond the kidney or fibrous pseudocapsule but is completely resected without evidence of tumor at or beyond the margins of resection. Tumor infiltrates, which are completely resected, can extend into the renal sinus, blood vessels and lymph nodes beyond the renal parenchyma, adjacent organs, or vena cava. ●Stage 3 – After surgery, residual tumor remains but is confined to the abdomen. This includes regional lymph node involvement, incomplete resection of the tumor, tumor penetration of the peritoneal surface, tumor thrombi of vessels at resection margins, tumor spillage, or previous biopsy. There is no evidence of hematogenous metastasis. ●Stage 4 – Hematogenous metastasis (eg, lung, liver, bone, brain) or lymph node involvement beyond the abdominopelvic region. ●Stage 5 – Bilateral renal involvement is present at the time of diagnosis.