TNM staging

T - primary tumour

• Tis: Tumour in situ, the tumour is contained within the lamina propria - it has not broken through the muscularis mucosae, thus the cells are still at their normal site
• T1: Tumour has invaded the submucosa, but not the muscularis propria
• T2: Tumour has invaded the muscularis propria, but has not extended beyond it
• T3: Tumour has invaded beyond the muscularis propria into the subserosa, the connective tissue surrounding these muscle coats, but has not perforated through the serosa or invaded adjacent tissue
• T4: Tumour has directly invaded other organs or perforated the visceral peritoneum

N - regional lymph nodes

• NX: Lymph nodes cannot be assessed
• N0: No regional lymph node metastasis
• N1: Metastasis to 1-3 nearby lymph nodes
• N2: Metastasis in 4 or more regional nodes

M - metastasis

• M0: No metastasis to distant tissues
• M1: Metastasis to distant tissues (including distant lymph nodes)

Dukes staging - 5 year survival probability

• A: Confined to bowel wall, no lymph node metastasis 95%
• B: Local spread outwith bowel wall, no lymph node metastasis 85%
• C: Lymph node metastases 60%
• D: Metastatic disease 8%