Table of Contents
Stages of Colon Cancer
Stages of colon cancer are used to describe how far the cancer has advanced. The higher the stage, the more severe the cancer has become. Three main factors determine the stages of colorectal cancer:
- The size of the original tumor.
- Whether the cancer is present in the lymph nodes
- Whether cancer has spread to other parts of the body (metastasis)
These factors are denoted by T (tumor), N (node), and M (metastasis), respectively.
Numbers from 0 to 4 are assigned to each factor to indicate severity. If not enough information could be assessed about a factor, then the letter X is used in place of a number. After all the T, N, and M scores have been assigned, the cancer stage can be determined.
Here is the TMN grading system in more detail:
- TX: The primary tumor cannot be evaluated.
- T0 (T plus zero): There is no evidence of cancer in the colon.
- Tis: Indicates carcinoma in situ. Cancer cells are found only in the top layers of the colon’s inner lining (mucosa).
- T1: The tumor has grown through the mucosa and into the submucosa.
- T2: The tumor has grown into the muscle layers that contract to push contents of the intestines along.
- T3: The tumor has grown through the muscle layers and into the subserosa, a thin layer of connective tissue beneath the outer layer of some parts of the large intestine, or it has grown into tissues surrounding the colon.
- T4a: The tumor has grown through all layers of the colon.
- T4b: The tumor has grown into or has attached to other organs or structures.
- NX: The nearby lymph nodes cannot be evaluated.
- N0 (N plus zero): There is no spread to nearby lymph nodes.
- N1a: There are tumor cells found in 1 nearby lymph node.
- N1b: There are tumor cells found in 2 or 3 nearby lymph nodes.
- N1c: There are nodules made up of tumor cells found in structures near the colon that do not appear to be lymph nodes.
- N2a: There are tumor cells found in 4 to 6 nearby lymph nodes.
- N2b: There are tumor cells found in 7 or more nearby lymph nodes
- M0 (M plus zero): The disease has not spread to a distant organ.
- M1a: The cancer has spread to 1 other organ beyond the colon.
- M1b: The cancer has spread to more than 1 organ other than the colon. Stage 0 Colon Cancer
Abnormal cells or growths such as polyps are discovered on the inner lining of the colon. These abnormal cells or growths may or may not be cancerous at this early stage. If the cells are cancerous, then the cancer itself has not yet spread and is only present in the original cells they were found. This is medically known as “carcinoma in situ.”
Stage 1 Colon Cancer
Cancer has grown within the intestinal wall through the mucosa and into the submucosa. It may have also entered the muscle layers.
Stage 2 Colon Cancer
Stage 2 colon cancer is split into three sub-stages:
- Stage 2A: The cancer has reached the serosa (the intestine’s outer layer) but has not yet penetrated it completely. It has not reached the lymph nodes or any nearby or distant organs.
- Stage 2B: The cancer has grown through all the intestinal layers of the colon but has not yet reached the lymph nodes or distant organs.
- Stage 2C: The cancer has grown through all the colon’s intestinal layers and spread to nearby organs or tissues. There is still no evidence of cancer reaching the lymph nodes or distant organs.
Stage 3 Colon Cancer
The third stage of colon cancer also has three sub-stages:
- Stage 3A: The cancer has grown through the mucosa and has spread to the submucosa. It may have also reached the muscle layer. The cancer has spread to a maximum of three lymph nodes near the site of the original tumor.
- Stage3B: The cancer has grown to the serosa (outermost layer) of the colon and may have spread to other organs and tissue nearby. It has also spread to a maximum of three lymph nodes near the primary site but has not spread to distant organs.
- Stage 3C: The cancer has grown into or through the serosa (outermost layer) of the colon and may have spread to four or more lymph nodes near the primary site. The cancer has spread to nearby organs.
Stage 4 Colon Cancer
At stage 4, tumors can be of any size, and lymph nodes may or may not be infected with cancer.
Colorectal cancer stage 4 can be divided into a further two sub-stages:
- Stage 4A: The cancer has spread to one other organ.
- Stage 4B: The cancer has spread to more than one other organ.
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