Table 1: SIOPS and NWSTG Wilms tumor staging system according to anatomical extension.
Staging system for renal tumors according SIOP 2001 protocols (after chemotherapy) | Staging system for renal tumors according NWSTG protocols (before chemotherapy) | |
Stage I |
Tumor is limited to the kidney or surrounded with fibrous pseudocapsule. The renal capsule or pseudocapsule may be in-filtrated with the tumor, but it does not reach the outer surface. Tumor is completely resected. - Tumor may be protruding into the pelvic system and “dip- ping” into the ureter but not infiltrates its wall. -T vessels of the renal sinus are not involved. - Intrarenal vessel involvement may be present. |
Tumor is limited to the kidney and completely resected. - Tumor was not ruptured before or during removal - The vessels of the renal sinus are not involved beyond 2 mm. -There is no residual tumor apparent beyond the margins of excision. |
Stage II |
The tumor extends through the renal capsule into perirenal fat but is completely resected. - The tumor infiltrates the renal sinus and/or invades blood and lymphatic vessels outside the renal parenchyma but is completely resected. - The tumor infiltrates adjacent organs or vena cava but is completely resected. |
- Tumor extends beyond the kidney but is completely excised. - No residual tumor is apparent at or beyond the margins of excision - Tumor thrombus in vessels outside the kidney is stage II if the thrombus is removed in block with the tumor. |
Stage III |
Incomplete excision of the tumor which extends beyond resection margins - any abdominal lymph nodes are involved - tumor rupture before or intraoperatively - the tumor has penetrated through the peritoneal surface - tumor thrombi present at resection margins of vessels or ureter. - The tumor has been surgically biopsied prior to preoperative chemotherapy or surgery. |
Residual tumor confined to the abdomen. - Lymph nodes in the renal hilum or the periaortic chains. - Diffuse peritoneal contamination by the tumor. - Implants are found on the peritoneal surfaces. - Tumor extends beyond the surgical margins either microscopically or glossy. - Tumor is not completely respectable because of local infiltration into vital structures. |
Stage IV |
Hematogenous metastases (Lung, liver, bone, brain etc.) or lymph node metastases outside the abdomino-pelvic region. | Presence of hematogenous metastases or metastases to distal lymph nodes. |
Stage V | Bilateral renal tumors at diagnosis. | Bilateral renal involvement at the time of initial diagnosis. |