Table 1.

North American National Wilms Tumor Study Group staging system for renal tumours

Stage	Description
Stage I	Tumour confined to the kidney without capsular or vascular invasion
Stage II	Tumour beyond renal capsule, vessel infiltration
Stage III	Positive lymph nodes in the abdomen or pelvis, peritoneal invasion or residual tumour at surgical margins or intraoperative tumour rupture
Stage IV	Metastatic disease outside the abdomen or pelvis
Stage V	Bilateral tumours at original diagnosis