| Stage | Extent of disease |
| I | - Complete resection at any site, including coccygectomy for sacrococcygeal site;
- Must have negative tumor margins and intact capsule;
- For any tumors involving abdominal cavity or retroperitoneum, peritoneal fluid or washings must be done for cytology and be negative for malignant cells;
- Lymph nodes ≤1 cm by imaging of abdomen, pelvis, and chest. (Note: Nodes 1 to 2 cm require short-interval follow-up in 4 to 6 weeks. If nodes are unchanged at 4 to 6 weeks [1 to 2 cm], consider biopsy or transfer to chemotherapy arm. If growing, transfer to chemotherapy arm. For any tumors involving abdominal cavity or retroperitoneum, peritoneal fluid or washings must be done for cytology and be negative for malignant cells.)
|
| II | - Microscopic residual disease;
- Gross total resection with preoperative biopsy, intraoperative biopsy, microscopic residual disease, or pathologic evidence of capsular disruption;
- Lymph nodes negative by abdomen, pelvic, and chest imaging. Peritoneal fluid negative.
|
| III | - Gross residual disease or biopsy only;
- Lymph nodes positive with tumor resection. Lymph nodes ≥2 cm or lymph nodes >1 cm but <2 cm on short axis by multiplanar imaging CT that fail to resolve on reimaging at 4 to 6 weeks.
|
| IV | - Distant metastases, including liver, lung, bone, and brain.
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