This is a staging system for an appendix tumour but shows the typical form. Different tumours have a similar basic idea though the details may vary
Tumour (T) :Using the TNM system, the "T" plus a letter or number (0 to 4) is used to describe the size and location of the tumour
- TX: The primary tumour cannot be evaluated.
- T0: There is no evidence of cancer in the appendix.
- Tis: This refers to carcinoma in situ (also called cancer in situ). Cancer cells are found only in the first layers lining the inside of the appendix.
- T1: The tumour has invaded the submucosa, which is the next deepest layer of the appendix.
- T2: The tumour has invaded the muscularis propria.
- T3: The tumour has grown through the muscularis propria and into the subserosa (a thin layer of connective tissue) of the appendix or into the mesoappendix, which is an area of fatty tissue next to the appendix that provides the blood supply for the appendix.
- T4: The tumour has grown through the visceral peritoneum, which is the lining of the abdominal cavity, or it has invaded other nearby organs.
- T4a: The tumour has invaded the visceral peritoneum.
- T4b: The tumour has invaded other organs or structures, such as the colon or rectum.
Node (N): "N" in the TNM system stands for lymph nodes.
- NX: The regional lymph nodes cannot be evaluated because of a lack of information.
- N0: There is no regional lymph node metastasis.
- N1: Cancer has spread to 1 to 3 regional lymph nodes.
- N2: Cancer has spread to 4 or more regional lymph nodes.
Metastasis (M): The "M" in the TNM system describes cancer that has spread to other parts of the body, such as the liver or lungs.
- M0: Cancer has not metastasized.
- M1: There is distant metastasis.
- M1a: This refers to an area of spread called intraperitoneal acellular mucin.
- M1b: This refers to metastasis within the peritoneum beyond M1a.
- M1c: This refers to metastasis beyond the peritoneum.
Grade (G): Histological grade (G)
- GX: The tumor grade cannot be identified.
- G1: The tumor cells are well-differentiated.
- G2: The tumor cells are moderately differentiated.
- G3: The tumor cells are poorly differentiated.
- G4: The tumor cells are undifferentiated.