Apart from the numbered stages, there is also a system known as the TNM staging method developed by the American Joint Committee on Cancer. The initial staging is given at the time of diagnosis. The stages could be changed or updated based on the condition of the patient and the improvement or progression of the condition.

In the TNM staging method, these three alphabets denote where or how far cancer or the tumor has spread. Though colon cancer is also staged with numbers, TNM staging is widely used to prepare reports, like pathological reports. Most cancers have a similar staging system except the brain, spinal cord, and blood cancer, as they have different parameters of staging.

What does TNM stand for?
T : This is the initial stage or size of the primary tumor in the colon when it is diagnosed. Stage T also means that cancer has spread to the wall of the colon and nearby tissues.

N: When a person is said to have colon cancer Stage N, it implies that cancer has spread from the colon to the nearby lymph nodes in the colon or rectum.

M: Stage M of colon cancer is serious and implies that cancer has spread beyond the colon to the other organs and of the body.

TNM staging with numbers
Along with TNM, you are also likely to see numbers after each alphabet.

Stage T
Stage T uses X, 0, 1, 2, 3, 4 where each number further details the staging of the primary tumor.

• TX : The doctors are unable to measure the primary tumor.
• T0 : The tumors cannot be found.
• T1 to T4 : The numbers indicate the size of the primary tumor. T1 denotes a smaller primary tumor while T4 indicates that the tumor is grown in size and spread to other tissues.

Stage N
Stage N uses X, 0, 1, 2, and 3 to give details of how much of the cancer is present in the lymph nodes. It also denotes the number of cancerous lymph nodes.

• NX : Cancer in the lymph nodes is not measurable.
• N0 : The nearby lymph nodes are clear and cancer from the colon has not reached it.
• N1, N2, N3 : These numbers indicate the number of lymph nodes that have cancer. They are also further classified into N1a, N1b, N1c, and N2a and N2b based on how many lymph nodes have been affected by cancer.

Stage M
This is the stage when cancer spreads to the other organs and is medically termed as Metastasis. Stage M is further detailed into X, 0, and 1.

• MX : When the metastasis cannot be measured, it is termed as MX.
• M0 : When the cancer is contained to the colon and has not spread to any part of the body.
• M1 : Cancer has spread to the other part of the body. M1 is further detailed as M1a, M1b, and M1 C, depending on the number of organs affected.

If a pathology report says that the person has colon cancer stage T3N2M1, it would mean that the primary tumor has grown bigger (T3), and cancer has invaded the nearby lymph node tissues (N2), and has spread to a nearby organ.