Where Does Colon Cancer Spread To In the Body?

Colon cancer is a cancerous growth that originally grows in the colon (large intestine), as the name implies. When it is treated at early stage, there is greater chance for patient to have better outcome and prognosis since at this stage the treatment is most likely to work. But when it has spread, it is more difficult to treat. Where does it usually spread to in the body?

In general, the cancer is classified into four main stages; stage I, II, III, and IV. However there is also the stage of when all cancer cells are still completely in the inner lining of the bowel, this stage is called CIS ‘carcinoma in situ’ or ‘stage 0’.

Another guide to classify the progression of cancer is TNM standard. It stands for Tumor, Node, and Metastases. T points to the size of tumor, N points to any lymph nodes that are affected by cancerous cells, and M describes whether the cancer cells has spread to another distinct organ of the body.

T parameter consists of:

1. T1, the cancer cells are completely only in the inner layer of the colon.
2. T2, the cancer cells are not only in the inner layer but also have grown into the muscle layer of the colon wall.
3. T3, the cancer cells cause bigger cancerous tumor that has grown into both inner and outer lining of the colon wall.
4. T4, the size of tumor is usually bigger than in T3 and it may also affect another part of the colon or even the nearby structures /organs.

Lymph nodes are network of glands throughout the body that has important function to help drain away damaged cells, waste fluid, and waste products. The cancerous cells in the colon can affect the nearby lymph nodes. For this case, experts use N parameter, this includes:

1. N0, the cancer has not affected any lymph node.
2. N1, 1-3 lymph nodes have been affected.
3. N2, 4 or more lymph nodes have been affected.

And for M parameter, it points to 2 main conditions; the cancer has not spread to any distinct organ (M0) and the cancer has spread to one or more distinct organs (M1).

Stage 0 (CIS)

If your doctor says that your cancer is at ‘stage 0’, this means that all the cancer cells are still contained within the inner bowel lining. In this phase, the cancerous cells are at very low risk of spreading.

See also risk factors that put you at high risk of having colon cancer, in this post!

Stage I

Based on TNM parameter, this stage includes T1, N0, M0 or T2, N0, M0. In other words, the cancerous cells have grown through the colon’s inner lining or start to grow into the inner muscles wall (but no further).

Stage II

This stage includes T3, N0, M0 or T4, N0, M0. This means the cancerous tumor has grown through the outer covering of colon wall ‘or/and’ into tissues /organs next to the colon. But there’re still no any lymph nodes that are affected.

Stage III

It can be:

1. T1, N1, M0 or T2, N1, M0 – this means the cancerous tumor is still in the inner lining or has affected the muscle layer. And 1-3 nearby lymph nodes have been affected.
2. T3, N1, M0 or T4, N1, M0 – this means the cancerous tumor gets larger in size, it has affected the outer lining or has grown into the surrounding tissues or organs, with 1-3 lymph nodes are contained cancerous cells.
3. Any T, N2, and M0 – this means the cancerous tumor can by any size, and 4 lymph nodes or more have been affected.

In this stage, the cancerous cells have not spread to any other distinct organ /part of the body.

Stage IV

This most advance stage include (any T ‘T1 to T4’), (any N ‘N0 to N2’), and M1. And the worst thing is the cancer has grown to other distinct parts of the body.

When it comes to talking about cancer of colon that has spread, this means that the cancerous cells have spread to distinct organs (metastasis) or stage IV!

*Image credit to Cancer Research UK

Theoretically, the cancer can spread to any part of the body. But for colon cancer, if it does spread to distinct organs, it commonly affects liver and lungs.

In general, the spread of the cancer cells can include: