Editing Wilms' tumor (section)

=== Staging ===

Staging is a standard way to describe the extent of spread of Wilms' tumors<ref>{{Cite web|title = How is Wilms tumor staged?|url = http://www.cancer.org/cancer/wilmstumor/detailedguide/wilms-tumor-staging|website = www.cancer.org|access-date = 2015-11-15}}</ref> and to determine prognosis and treatments. Staging is based on [[Anatomical terms of location|anatomical]] findings and tumor cells pathology.<ref>{{Cite web|title = Wilms Tumor - Childhood - Stages|url = http://www.cancer.net/cancer-types/wilms-tumor-childhood/stages|website = Cancer.Net| date=25 June 2012 |access-date = 2015-11-15}}</ref><ref>{{Cite web|title = Treatment by type and stage of Wilms tumor|url = http://www.cancer.org/cancer/wilmstumor/detailedguide/wilms-tumor-treating-by-stage|website = www.cancer.org|access-date = 2015-11-13}}</ref> According to the extent of tumor tissue at the time of initial diagnosis, four stages are considered, with a fifth classification for bilateral involvement.{{citation needed|date=April 2021}}

==== Stage I ====
In Stage I Wilms' tumor (43% of cases), all of the following criteria must be met: {{citation needed|date=April 2021}}
* Tumor is limited to the [[kidney]] and is completely excised .
* The surface of the [[renal capsule]] is intact.
* The tumor is not ruptured or biopsied (open or needle) prior to removal.
* No involvement of extrarenal or renal sinus lymph-vascular spaces
* No residual tumor apparent beyond the margins of excision.
* Metastasis of tumor to lymph nodes not identified.

==== Stage II ====
In Stage II (23% of cases), 1 or more of the following criteria must be met: {{citation needed|date=April 2021}}
* Tumor extends beyond the kidney but is completely excised.
* No residual tumor apparent at or beyond the margins of excision.
* Any of the following conditions may also exist:
** Tumor involvement of the blood vessels of the renal sinus and/or outside the renal parenchyma.
** Extensive tumor involvement of renal sinus soft tissue.

==== Stage III ====
In Stage III (20% of cases), 1 or more of the following criteria must be met: {{citation needed|date=April 2021}}
* Inoperable primary tumor.
* Lymph node metastasis.
* Tumor is present at surgical margins.
* Tumor spillage involving peritoneal surfaces either before or during surgery, or transected tumor thrombus.
** The tumor has been biopsied prior to removal or there is local spillage of tumor during surgery, confined to the flank.

==== Stage IV ====
Stage IV (10% of cases) Wilms' tumor is defined by the presence of hematogenous metastases (lung, liver, bone, or brain), or lymph node metastases outside the abdominopelvic region.{{citation needed|date=April 2021}}

==== Bilateral ====
5% of Wilms' tumor cases at the time of initial diagnosis are bilateral involvements, which pose unique challenges to treatment. An attempt should be made {{according to whom|date=November 2018}} to stage each side according to the above criteria (stage I to III) on the basis of extent of disease prior to biopsy. Bilateral Wilms' tumors are as a whole placed in Stage V.