Rupture or spillage confined to the flank, including biopsy of the tumor, is no longer included in stage II and is now included in stage III.
In stage III Wilms tumor (21% of patients), there is residual nonhematogenous tumor present following surgery that is confined to the abdomen. Any one of the following may occur:
- Lymph nodes within the abdomen or pelvis are involved by tumor. (Lymph node involvement in the thorax or other extra-abdominal sites is a criterion for stage IV.)
- The tumor has penetrated through the peritoneal surface.
- Tumor implants are found on the peritoneal surface.
- Gross or microscopic tumor remains postoperatively (e.g., tumor cells are found at the margin of surgical resection on microscopic examination).
- The tumor is not completely resectable because of local infiltration into vital structures.
- Tumor spillage occurs either before or during surgery.
- The tumor is treated with preoperative chemotherapy and was biopsied (using Tru-cut biopsy, open biopsy, or fine-needle aspiration) before removal.
- The tumor is removed in more than one piece (e.g., tumor cells are found in a separately excised adrenal gland; a tumor thrombus within the renal vein is removed separately from the nephrectomy specimen). Extension of the primary tumor within vena cava into thoracic vena cava and heart is considered stage III, rather than stage IV, even though outside the abdomen.
In stage IV Wilms tumor (11% of patients), hematogenous metastases (lung, liver, bone, brain), or lymph node metastases outside the abdominopelvic region are present. The presence of tumor within the adrenal gland is not interpreted as metastasis and staging depends on all other staging parameters present. The primary tumor should be assigned a local stage following the above criteria which determines local therapy. For example, a patient may have stage IV, local stage III disease.
Stage V and those predisposed to developing Wilms tumor
In stage V Wilms tumor (5% of patients), bilateral involvement by tumor is present at diagnosis. Previously an attempt was made to stage each side according to the above criteria on the basis of the extent of disease. The current COG-AREN0534 protocol recommends preoperative chemotherapy in hopes of reducing tumor size to allow renal-sparing surgical procedures. In these patients, renal failure rates approach 15% at 15 years posttreatment, making renal-sparing treatment important.
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- Wilms' tumor: status report, 1990. By the National Wilms' Tumor Study Committee. J Clin Oncol 9 (5): 877-87, 1991.
- Perlman EJ: Pediatric renal tumors: practical updates for the pathologist. Pediatr Dev Pathol 8 (3): 320-38, 2005 May-Jun.
- Breslow NE, Collins AJ, Ritchey ML, et al.: End stage renal disease in patients with Wilms tumor: results from the National Wilms Tumor Study Group and the United States Renal Data System. J Urol 174 (5): 1972-5, 2005.