Table 4. TNM staging (by AJCC and ENETS) for neuroendocrine appendiceal tumors.
| Stage | T (AJCC) | T (ENETS) | N (AJCC/ENETS) | M (AJCC/ENETS) |
|---|---|---|---|---|
| X | Primary tumor not determined, or any T | Primary tumor not determined, or any T | Lymph nodes not determined, or any N | Metastatic disease not determined, or any M |
| 0 | No evidence of primary tumor | No evidence of primary tumor | No lymph node metastasis | No distant metastasis |
| I | Ia: Tumor ≤1 cm Ib: Tumor 1–2 cm |
T1 Tumor ≤1 cm invading submucosa and muscularis propria | Lymph node metastasis | Distant metastasis |
| II | Tumor 2–4 cm or with extension to the cecum | Tumor ≤2 cm with invasion of submucosa or muscularis propria, and/or minimal invasion (up to 3 mm) of subserosa/mesoappendix | ||
| III | Tumor >4 cm or with extension to the ileum | Tumor >2 cm and/or extensive invasion (>3 mm) of subserosa/mesoappendix | ||
| IV | Tumor directly invades other adjacent organs or structures, e.g., abdominal wall and skeletal muscle a | Tumor invades peritoneum/other organs |
Abbreviations: AJCC, American Joint Committee on Cancer; ENETS, European Neuroendocrine Tumor Society.
Note : Stage I: T1 N0 M0; stage II: T2–3 N0 M0; stage III: T4 N0 M0 or Tx N1 M0; and stage IV: Tx Nx M1.
a
Tumor adherent to other organs or structures grossly classified as cT4 but if microscopically negative adhesion as pT1–3 depending on depth of wall invasion.