Wilms’ tumor

Contraindications to Primary Resection ⁽¹⁶⁾

·  High risk of renal failure for those with germline WT1 mutations (Denys-Drash, WAGR).

·   Unacceptable anesthesia risk due to:

a. Disease burden

b. Massive pulmonary disease or tumor embolus

c. Very large abdominal tumors causing pulmonary compromise

·   Surgeon judgment: Operation would lead to significant morbidity/ mortality, tumor spill, or residual tumor

· Solitary kidney

· IVC tumor thrombus above the level of the hepatic veins is an absolute contraindication; extension of thrombus to the retrohepatic cava is a relative contraindication 

·   Bilateral tumors or unilateral disease in patients with a predisposing condition

Staging of Wilms’ tumor according to COG staging system ⁽⁴⁶⁾

Stage I:

·  Tumor limited to kidney, completely resected.

·  The renal capsule is intact.

·  The tumor was not ruptured or biopsied prior to removal.

·   The vessels of the renal sinus are not involved.

·  There is no evidence of tumor at or beyond the margins of resection.

Stage II:

· The tumor is completely resected and there is no evidence of tumor at or beyond the margins of resection.

· The tumor extends beyond kidney, as is evidenced by any one of the following criteria: 

-There is regional extension of the tumor (i.e. penetration of the renal capsule, or extensive invasion of the soft tissue of the renal sinus, as discussed below).

-Blood vessels within the nephrectomy specimen outside the renal parenchyma, including those of the renal sinus, contain tumor.

Stage III:

·   Residual non-hematogenous tumor present following surgery and confined to 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 extraabdominal 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 (eg, 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 occurring either before or during surgery.

·  The tumor was biopsied (whether tru-cut, open or fine needle aspiration) before removal.

·  Tumor is removed in greater than one piece (eg, tumor cells are found in a separately excised adrenal gland; a tumor thrombus within the renal vein is removed separately from the nephrectomy specimen).

Note: 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.

Stage IV:

·       Hematogenous metastases (lung, liver, bone, brain, etc), 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).

Stage V:

·       Bilateral renal involvement by tumor is present at diagnosis. An attempt should be made to stage each side according to the above criteria based on the extent of disease.

Predisposing factors to develop bilateral WT: ⁽⁴⁷⁾

1.     Genetic disorders:

·  Beckwith-Wiedemann Syndrome.

·  WAGR Syndrome (Wilms tumor, aniridia, genitourinary abnormalities, mental retardation).

·  Simpson-Golabi-Behmel-Syndrome.

·  Denys-Drash Syndrome.

·  Frasier Syndrome.

·  Perlman Syndrome.

2.     Associated genitourinary anomalies.

3.     Contralateral nephrogenic rests in children <12 months.

4.     Diffuse hyperplastic perilobar nephroblastomatosis.