Generally after a patient starts to accommodate with the idea that he has cancer he will begin to wonder how many years will he live more and what treatment is suitable and available for him. The doctor will be asked about this and he will be able to give an answer to the patient only after staging the cancer.

Staging the cancer refers to determining the cancer's evolution, to see how much of the organism has been affected by this disease. It is of no importance in the process of staging the type of the cancer: lung, colon, rectal, etc; the cancer is staged by predetermined criteria and this is applied to all types of cancer.

The TNM staging is one of the most important ways of staging the cancer. Every year, the American Joint Committee on Cancer gathers its members and during a conference they talk about each cancer type, about researches, and new treatment possibilities for cancer. They also establish the details of staging the cancer for each type of cancer.

The T category determines how much the cancer has spread in the affected organ and if other organs have been affected by cancer too.

The N category refers to the lymph nodes and shows whether they got affected or not by the disease.

The M category shows whether metastasis is present in different areas of the body.

The colorectal cancer is a disease which affects the layers of the colon or of the rectum totally or partially, depending on the evolution of the cancer. The layers of the colon from the inside to the outside are: the mucosa, the submucosa, the muscularis propria, the subserosa and the serosa.

The T category shows how much the layers of the colon have been affected by the cancer.

Tx refers to the fact that the information is insufficient and so the cancer's evolution can not be determined.

Tis: it means that the cancer has affected only the mucosa and is also known as carcinoma in situ.

T1: the cancer has affected the mucosa and the submucosa too.

T2: the cancer has extended to the muscularis propria.

T3: the cancer has passed through the muscularis propria and has reached the subserosa.

T4: the cancer has affected all the colon's layers and it is spreading o the nearby organs.

The N category shows if the lymph nodes are affected and how many of them are in this situation.

Nx refers to the fact that the information is not sufficient for determining the lymph node involvement.

N0: it means that no lymph nodes are affected yet.

N1: the cancer has affected 1 to 3 local lymph nodes.

N2: the cancer is found in more than 4 local lymph nodes.

The M category shows whether the cancer has spread to other organs like lungs, liver or distant lymph nodes.

Mx refers to the fact that the information is incomplete and so there can not be determined whether the cancer has given metastasis or not.

M0: it means that no metastases are present.

M1: it means that metastasis can be seen.