T- Tumor

Describes the size of the tumor and whether it has begun to spread. A number is placed beside the T to describe the size and the extent to which it has propagated.

Tis: The cancer is in its earliest stage (in situ). It is growing in the mucosa but not beyond it.

T1: The cancer has grown into the internal layer (mucosa or submucosa) of the intestine.

T2: The cancer has grown into the intestinal layer.

T3: The tumor has spread into the outermost layer of the intestinal wall.

T4: The tumor has grown through the outermost layer of the intestinal wall, going beyond the wall of the intestine.

T4a: T4: The cancer has spread into nearby structures.

T4b: The cancer has caused a hole in the wall of the intestine and the cancer cells have spread outside the intestine.

N- Nodes

This is a description of whether the cancer has spread to the lymph nodes.

N0: No cancer cells in the lymph nodes.

N1 - There are cancer cells in as many as lymph nodes.

N2 - There are cancer cells in 4 or more lymph nodes.

M - Metastasis
This describes whether the cancer has spread to another part of the body, such as the liver or the lungs.M0 - The cancer has not spread to other parts of the body.

M1 - The cancer has spread to distant organs.

Numerical staging system

Stage 0 - The cancer is in the earlies stage and is only found in the mucosa (Tis N0 M0).

Stage 1 - The cancer is in the submucosa or muscle layer but has not spread to the lymph nodes or other parts (T1 N0 M0 or T2 N0 M0).

Stage 2 - The cancer has grown through the muscle wall or through the outer layer of the intestine and may be growing in nearby tissues. The cancer has not spread to the lymph nodes or other parts (T3 N0 M0 or T4 N0 M0).

Stage 3 - The tumor is of any size and has spread to the nearby lymph nodes but has not spread to any other part of the body (any T N1 or N2 M0).

Stage 4 - The cancer has spread to other parts of the body such as the liver or lungs.

Grading

Grading has to do with how the cancer cells look under the microscope compared to normal cells. A cancer's grade provides doctors with a quick sketch of how quickly it may develop.

Grade 1: Low-grade, or well-differentiated cancer: this means the cancer cells resemble normal cells and in general grow slowly and are less likely to spread.

Grade 2: Moderate or intermediate cancer: this means that the cancer cells have a more abnormal appearance and are slightly faster-growing.

Grade 3: High-grade or poorly differentiated cancer: this means that the cancer cells look very different than normal cells and can grow more quickly.