Stage 3 Colon Cancer

Classification Helps Direct Treatment and Predict Survival

An illustration of colon cancer.
A digital illustration of malignant tumors in a section of the colon. Sebastian Kaulitzk/Getty Images

There are five stages of colon cancer, designated from 0 to 4, which not only characterize the severity of the disease but help direct the course of treatment.

Stage 3 colon cancer is largely defined by the characteristics of the tumor and the spread (metastasis) of cancer from the original (primary) tumor to nearby lymph nodes. By contrast, with stage 2 cancer, the tumor remains largely constrained to the intestinal wall, while stage 4 involves the spread of cancer to distant organs.

How Colon Cancer Is Staged

There have been several different models long used to stage cancer, such as the Full Duke's classification started the 1930s and the Asler-Coller classification started in the 1950s. Today, both have been supplanted by the TNM classification which stages cancer by three characteristics:

  1. The extent to which the tumor ("T") has invaded the intestinal wall
  2. The degree of lymph node ("N") involvement
  3. The degree of metastasis ("M")

Moreover, since stage 3 cancer is defined by both the lymph nodes and the tumor itself, there will be additional sub-classifications based on these characteristics, designated as either A, B, or C.

Lymph Nodes in Cancer Staging

Our bodies have a lymphatic system comprised of lymph vessels and lymph nodes. As part of the body's immune defense, the lymphatic system collects waste and pathogens (like viruses and bacteria) in tissues outside of the circulatory system.

Lymph vessels are similar to blood vessels, but, instead of carrying blood, they carry a clear, watery fluid called lymph. Lymph helps transport waste and pathogens to the lymph nodes which are rich with lymphocytes (a type of immune cell). These cells help neutralize any disease-causing agent and effectively eliminate them from the body.

With colon cancer, any malignant cell that escapes the primary tumor can be collected by lymph and transported to a nearby node. If metastasis has occurred, this is where the evidence will first be seen. It is this characteristic helps establish the stage of the disease as well as the likely outcome.

Tumor Characteristics in Cancer Staging

In the TNM classification system, stage 3 colon cancer is further characterized by where the tumor is situated on or in the intestinal wall. This is broken down into four classifications:

  • T1 means that the tumor has penetrated the mucosal membranes of the inner intestinal wall.
  • T2 means that the tumor has spread to the muscles below.
  • T3 means that the tumor has penetrated the muscles but not the exterior intestinal wall.
  • T4 means that the exterior wall has been penetrated.

Designation of Stage 3 Colon Cancer

Once the degree of lymph node involvement and tumor characteristics are established, the cancer doctor (oncologist) will classify the stage of disease as follows:

  • Stage 3A means that one to three nearby lymph nodes are involved with either T1 or T2 characteristics.
  • Stage 3B means that one to three nearby lymph nodes are involved with either T3 or T4 characteristics.
  • Stage 3C means that four or more nearby lymph nodes are involved, irrespective of tumor classification.

Treatment for Stage 3 Colon Cancer

Treatment for stage 3 colon cancer generally consists of the surgical removal (resection) of the affected tissue, followed by chemotherapy. In a surgical resection, the surgeon will remove the part of the colon affected by the tumor and join the remaining ends together. Nearby lymph nodes would also be removed,

Chemotherapy would typically involve either the FOLFOX regimen (comprised of folinic acid, leucovorin, and oxaliplatin) or the CapeOx regimen (containing capecitabine and oxaliplatin).

Other modified regimens may be recommended based on your age and/or health status. Radiation therapy and/or chemotherapy may be used for people who aren’t healthy enough for surgery.

A Word From Verywell

According to the American Cancer Society, the five-year survival rate for people diagnosed with stage 3A colon cancer is 89 percent, while the rates for stages 3B and 3C are 63 percent and 59 percent, respectively.

It is important to note, however, that these figures aren't cast in stone.From an individual perspective, people with stage 3 colon cancer have been known to live for many years without remission or a reduction in the quality of life.

By taking action, building a solid support network, and taking things one step at a time, you have as much chance of beating colon cancer than anyone else. Keep focused and keep faith.


American Cancer Society. "Colorectal Cancer Stages." Atlanta, Georgia, updated December 11, 2017.

American Cancer Society. "What Are the Survival Rates for Colorectal Cancer, by Stage?" Atlanta, Georgia; updated March 2, 2017.