To first get a diagnosis of colon cancer, your doctor will need to collect a tissue sample, called a biopsy, from your colon during a flexible sigmoidoscopy or colonoscopy test. If this biopsy comes back showing colon cancer, your doctor will schedule you for surgery. This will allow the doctor to determine the extent, or stage, of your disease.
During surgery, the surgeon may remove portions of your colon. This tissue can be tested to see how far the colon cancer has spread. In addition to removing the cancer and possibly parts of your colon, the doctor may remove lymph nodes. These are glands located throughout the body that are part of the immune system.
When colon cancer spreads beyond the colon, it will often go into the lymph nodes that are closest to the tumor.
By looking at your lymph nodes, the doctors can determine how far the cancer has spread.
There are several different systems or ways of classifying colon cancer disease stage, but the most common is the American Joint Committee on Cancer (AJCC) system. You might also hear this referred to as the “TNM system.” T, N and M refer to three different aspects of colon cancer staging.
Along with the T, N and M, you will see numbers. Generally, the higher the number or letter, the more advanced the cancer is.
The T indicates how far the colon tumor has grown into your intestine wall. It also indicates whether the tumor has penetrated through the wall of the intestine into nearby areas.
The N describes whether and how far the cancer has spread into nearby lymph nodes. Lymph nodes are glands located throughout the body that are part of the immune system. When colon cancer spreads beyond the colon, it will often go into the lymph nodes that are closest to the tumor.
The M indicates whether the cancer has spread to other organs or areas of the body. The M refers to “metastasis,” which is the technical term that is used to describe when a cancer has moved into other body areas or organs.
The numbers that appear after T, N, and M provide more detail and indicate the severity of each feature. The higher the number, the more advanced the disease.
For example, T1 means the tumor has just penetrated through the first layer of the colon, while a T3 means it has grown all the way into the outermost layers of the colon. As another example, N1 means the tumor has spread into one to three nearby lymph nodes, while an N2 means the tumor has spread to four or more lymph nodes.
Sometimes you may see the letter “x” by T, N, and M. This means the doctor did not have enough information to make a determination for that particular feature or aspect of your cancer.