Staging In Depth
Staging and T, N, M Categories
Three key factors are used to determine the cancer stage: T (the size of the tumor), N (if the lymph nodes are involved in the cancer) and M (if the cancer has metastasized, or spread, to other organs in the body).
T Categories
The colon and rectum walls are made up of a series of layers. The T categories describe how far through the layers the tumor may have grown. The layers are:
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Mucosa
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The mucus membrane that makes up the inner lining
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Muscularis mucosa
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Thin layer of muscle fibers
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Submucosa
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Layer under the muscularis mucosa
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Muscularis propria
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Thick, main muscle layer
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Serous membrane
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Thin outermost layer that covers the colon but not the rectum
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The T categories for colorectal cancer are:
| Tx |
The extent of the tumor cannot be determined
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Tis
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Cancer involves only the mucosa
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T1
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Tumor has grown through the muscularis mucosa and into the submucosa
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T2
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Tumor has grown through the submucosa and into the muscularis propria
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T3
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Tumor has grown through the muscularis propria and into serous membrane, but has not grown into regional (nearby) tissue or organs.
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T4
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Tumor has grown through the colon or rectum wall and into regional tissue or organs.
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N Categories
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Nx
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It cannot be determined if lymph nodes are involved
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N0
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No cancer in the lymph nodes
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N1
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Cancer found in up to three regional lymph nodes
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N2
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Cancer found in four (or more) regional lymph nodes
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M Categories
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Mx
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It cannot be determined if cancer has metastasized (spread)
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M0
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Cancer has not metastasized to any distant organs
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M1
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Cancer has metastasized to distant organs
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Overall Staging
Once the T, N and M categories are determined, the information is combined and used to decide the overall cancer stage. Overall staging for colorectal cancer uses Stage I through Stage IV. The lower the staging number, the less advanced the cancer.
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Stage
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TNM category
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What It Means
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Stage 0
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Tis, N0, M0
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Earliest stage of cancer. Tumor has not grown beyond the mucosa. This stage is also known as carcinoma in situ or intramucosal carcinoma.
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Stage I
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T1, N0, M0
T2, N0, M0
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T1 means cancer has grown through the muscularis mucosa into the submucosa. T2 means cancer has grown through the submucosa into the muscularis propria. No lymph nodes are involved.
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Stage IIA
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T3, N0, M0
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Cancer has grown into serous membrane but has not spread to lymph nodes or other organs.
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Stage IIB
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T4, N0, M0
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Cancer has grown through colon or rectum wall into regional tissue or organs. Lymph nodes and distant tissue and organs are not involved.
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Stage IIIA
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T1, N1, M0
T2, N1, M0
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T1 means cancer has grown through the mucosa into the submucosa. T2 means cancer has grown through the submucosa into the muscularis propria. Up to three lymph nodes are involved. There is no spread to distant tissue or organs.
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Stage IIIB
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T3, N1, M0
T4, N1, M0
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T3 means cancer has grown into the serous membrane (outer most layers) but has not spread to regional organs. T4 means cancer has grown through colon or rectal wall and into regional tissue or organs. Up to three lymph nodes are involved. There is no spread to distant tissue or organs.
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Stage V
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Any T, Any N, M1
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Cancer may or may not have grown through the colon and rectal wall. Regional lymph nodes may or may not be involved. Cancer has spread to other distant organs.
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Next: Treatment Options