| T: primary tumor | |
| TX | Primary tumor cannot be assessed |
| T0 | No evidence of primary tumor |
| Tis | Carcinoma in situ |
| T1 | Tumor invades submucosa |
| T2 | Tumor invades muscularis propria |
| T3 | Tumor invades subserosa or into non peritonealized pericolic / perirectal tissues |
| T4a | Tumor perforates visceral peritoneum |
| T4b | Tumor directly invades other adjacent structures |
| N: regional lymph nodes | |
| NX | Regional lymph nodes cannot be assessed |
| N0 | No regional lymph node metastasis |
| N1a | Metastasis in 1 regional lymph node |
| N1b | Metastasis in 2-3 regional lymph nodes |
| N1c | Tumour deposits in the subserosa or in non peritonealized perirectal soft tissue without regional lymph node metastasis |
| N2a | Metastasis in 4-6 regional lymph nodes |
| N2b | Metastasis in 7 or more regional lymph nodes |
| M: distant metastasis | |
| M0 | No distant metastasis |
| M1a | Metastasis confined to one organ (liver, lung, ovary, non regional lymph nodes) without peritoneal metastases |
| M1b | Metastasis in more than one organ |
| M1c | Metastasis to the peritoneum with or without other organ involvement |
