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Colorectal Cancer Stages

Colorectal cancer can advance through five distinct stages, labeled 0 to 4, increasing in numerical value with the severity and spread of the disease.

March 15, 2019 3 minute read

When a patient is diagnosed with colorectal cancer, one of the first questions they’ll want to be answered is: “What stage is it?” Stages of colon cancer, like most others involving a tumor, are broken down into five groups, labeled 0 to 4. The numbers increase with the severity of the disease.

Before we get into the specifics of cancer stages, here are several key facts about colorectal cancer:

  • Colorectal cancer is cancer of the colon or rectum.
  • Symptoms of colorectal cancer include, but are not limited to, a change in bowel habits, narrowed stool (about the size of a pencil), unexplained weight loss, bloody stool, rectal bleeding, and abdominal pain.
  • The recommended age to start regular screening for colorectal cancer is 45 years old, according to the American Cancer Society.
  • The average American has a 1 in 17 chance of developing colorectal cancer in their lifetime, without any additional risk factors present.
  • Colorectal cancer is the second-most deadly type of cancer, following only lung cancer.

Colorectal Cancer Stages

Staging is a way to describe where cancer is located, how far it has spread, and what other organs, if any, have been compromised by cancerous cells. The stages of colon cancer are most often determined according to a standard developed by the American Joint Committee on Cancer, called the TNM Classification of Malignant Tumors staging system—a globally recognized methodology for classifying the extent of spread of cancer. The T describes the size and scope of the primary tumor, the N describes the local lymph nodes that are affected, and the M describes whether or not cancer has metastasized.

Here's a helpful breakdown:

Stage 0

If you are diagnosed with stage 0 colorectal cancer, it means that the cancer cells have only been found in the mucosa and has not spread beyond the inner lining of the colon.

Stage 1

If you are diagnosed with stage 1 colorectal cancer (T1 or T2, N0, M0), it means that the cancer cells spread beyond the mucosa and have infiltrated the muscular layer of the colon, but still has not affected any nearby lymph nodes.

Stage 2

This stage may describe one of three subsections, labeled IIA, IIB and IIC.

In stage IIA (T3, N0, M0), cancerous cells have grown to the outer layer of the colon, but not all the way through it. Nearby lymph nodes are not affected in stage IIA.

In stage IIB (T4a, N0, M0), cancerous cells have not only grown to the outer layer of the colon, but through it to the membrane holding abdominal organs in place, called the visceral peritoneum. Again, nearby lymph nodes are not affected in this stage, nor are other organs.

In stage IIC (T4b, N0, M0), cancer extends through the colon wall and has also spread to nearby organs or structures, but does not affect any nearby lymph nodes.

Stage 3

As in stage 2, stage 3 colorectal cancer may be broken down into three subsections, labeled IIIA, IIIB and IIIC.

In stage IIIA (T1 or T2, N1 or N1c, M0; or T1, N2a, M0), cancer has spread through the colon wall and also affects up to three nearby lymph nodes. Distant lymph nodes remain unaffected in stage IIIA.

In stage IIIB (T3 or T4a, N1 or N1c, M0; T2 or T3, N2a, M0; or T1 or T2, N2b, M0), cancer has spread to up to three nearby lymph nodes and may affect local organs or structures, but not to distant nodes, organs, or structures.

In stage IIIC (T4a, N2a, M0; T3 or T4a, N2b, M0; or T4b, N1 or N2, M0), cancer has spread to four or more lymph nodes, and to nearby organs.

Stage 4

If a patient is diagnosed with stage 4 colorectal cancer, it means that cancer has metastasized in other organs, such as the lungs or liver (any T, any N, M1a). Stage 4 colorectal cancer is the most advanced form of the disease, and is further divided into two subsections, IVA and IVB.

In stage IVA, cancer has only metastasized in one additional organ. If cancer has metastasized in more than one additional organ, it is considered to be stage IVB cancer.


According to the Centers for Disease Control and Prevention, colorectal cancer most often develops from precancerous polyps. With proper screening, your doctor can detect polyps and remove them before they become cancerous.

Talk to a doctor to see if screening is right for you. Gastroenterology Associates specializes in helping restore you and your family to optimal digestive health. Schedule your consultation, today.

Topics: colorectal cancer