These Are the 4 Colon Cancer Stages

A colon cancer diagnosis

Colon cancer is treatable, and the earlier it’s detected with screening tests, the better.

There will be an estimated 104,270 new cases of colon cancer diagnosed in the United States in 2021, according to the American Cancer Society (ACS). The good news is that these cancers can be found earlier with colorectal cancer screening tests, such as colonoscopies,

During a colonoscopy, a doctor examines the colon for changes or abnormalities and removes polyps that could otherwise grow into cancer. A colonoscopy can also detect cancer early, when it’s more treatable.

“For colorectal cancer, as long as it’s caught in an earlier stage, most cases can be cured,” says David Liska, MD, director of the Center for Young-Onset Colorectal Cancer and director of the Weiss Center at the Cleveland Clinic.

In fact, the American Cancer Society says the five-year survival rate for localized cancer is 91 percent. “Even at stage 3, the prognosis is very good for the majority of patients,” he says.

What is colon cancer?

The colon is the longest portion of your large intestine, a 5-foot long muscular tube that’s part of the digestive tract. It’s made up of four sections:

• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon

It’s the colon’s job to absorb water and salts from leftover food waste in order to form your stool, which will then pass into the rectum where it stays until you go to the bathroom. Colorectal cancer includes cancers of the large intestine, whether they are in the colon or the rectum, which makes up the last six inches of the tract.

In the inner lining of your colon, polyps (growths) can develop. These are usually benign, but some types of polyps can grow to become cancerous.

If a polyp is found during a colonoscopy,  your doctor will remove it. If benign, it will not have the opportunity to become cancer. A pathologist will examine polyps that are removed to look for cancerous changes.

Over time, a cancerous polyp can grow from the inside mucous layer in the colon through the muscular wall of the colon, according to the ACS. Cancer can then spread into lymph nodes or other parts of your body.

Risk factors for colon cancer

The following are risk factors for colorectal cancer:

• Having inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis
• A personal or family history of colorectal cancer or colorectal polyps
• Certain genetic syndromes, such as Lynch syndrome
• A sedentary lifestyle
• Not eating enough fruits and vegetables
• A low-fiber, high-fat diet
• Eating processed meats
• Being overweight or obese
• Smoking or drinking alcohol

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Stages of colon cancer

If you’ve been diagnosed with colon cancer, your doctor will let you know the stage of colon cancer.

“The stage tells you the prognosis, or the risk of the cancer not being able to be cured or returning. For doctors, the stage provides information about how to treat the cancer,” says Dr. Liska.

Most colorectal cancer doctors follow the TNM staging system, which uses three factors to assign the stage. According to the National Cancer Institute (NCI), those factors are:

T: Tumor size of tumor and whether this primary tumor has spread

N: Number of nearby lymph nodes with cancer

M: Metastasis, or cancer that has spread to other parts of the body

The tricky thing for patients is that doctors are usually only aware of the T and N part after the cancer has been removed, says Dr. Liska.

At that time, the pathologist will look at how deep the tumor has traveled and examine removed lymph nodes to see if they were affected.

Low-grade and high-grade tumors

Tumors are also categorized as low-grade or high-grade. These terms define how abnormal the cells look under a microscope. This is called differentiation; in a well-differentiated tumor, for instance, the cells look relatively normal.

Well or moderately differentiated cancers are considered low-grade, while poorly differentiated cancers are high-grade.

Higher-grade tumors tend to be more aggressive.

Stage 0 colon cancer

The classification system uses stages 1 through 4 for cancer. However, there is an outlier, and it’s stage 0.

“This is not really a cancer,” says Dr. Liska. It may happen if you had a polyp removed from the colon that has dysplasia, a precancerous condition. At stage 0, cells in the polyp are abnormal but have not yet progressed to cancer because the polyp has not penetrated through the inner lining of the colon wall.

“For this type of polyp, removing the polyp is the treatment,” Dr. Liska says. “No further treatment is usually needed.”

Your doctor will advise as to when to have your next colonoscopy, possibly in one year.

Stage 1 colon cancer

Stage 1 indicates cancer. At this point it’s spread into the middle layers of the colon.

Many times, complete removal of a cancerous polyp during a colonoscopy is the only treatment needed for stage 1 colon cancer. Other times—if there are cancer cells at the edges of the polyp or the cancer is high grade—patients need additional surgery to remove the remaining cancer cells.

Stage 2 colon cancer

This stage of colon cancer is further divided into stage 2A, 2B, or 2C, which indicate how far into the colon wall the tumor has grown. According to the NCI, the categories of stage 2 colon cancer mean the following:

Stage 2A: The cancer spread through the muscle and into the serosa (outermost layer) of the colon wall.

Stage 2B: It has spread through the serosa to the visceral peritoneum, the tissue that lines the organs in the abdomen.

Stage 2C: It has spread through the serosa to nearby organs.

No matter the subcategory, a stage 2 cancer has not spread to the lymph nodes or around the body.

Treatment is likely surgery to remove part of the colon and nearby lymph nodes, and chemotherapy may be recommended.

Stage 3 colon cancer

At stage 3, colon cancer has spread to nearby lymph nodes. Like stage 2, stage 3 colon cancer is divided into three subcategories based on how far the cancer has grown into the colon wall, plus the number of lymph nodes affected. Cancer has not yet metastasized (spread) at this point.

According to the NCI, here’s how doctors categorize stage 3 colon cancer:

Stage 3A

• Cancer has spread through the mucosa (the innermost layer) of the colon wall to the submucosa (layer of tissue next to the mucosa) or to the muscle layer of the colon wall. The cancer is in one to three nearby lymph nodes, or cancer cells can be found in tissue near these lymph nodes.
• Or cancer has spread through the mucosa to the submucosa and four to six nearby lymph nodes.

Stage 3B

• Cancer has spread through the muscle layer of the colon wall to the serosa of the colon wall, or has spread through the serosa to the visceral peritoneum. Cancer can be found in one to three nearby lymph nodes or in tissue near the lymph nodes.
• Or cancer has spread to the muscle layer or serosa, as well as four to six nearby lymph nodes.
• Or cancer has spread through the mucosa to the submucosa, or to the muscle layer of the colon wall, as well as to seven or more nearby lymph nodes.

Stage 3C

• Cancer has spread through the serosa of the colon wall to the visceral peritoneum and four to six nearby lymph nodes.
• Or cancer has spread through the muscle layer of the colon wall to the serosa, or through the serosa to the visceral peritoneum, as well as seven or more nearby lymph nodes.
• Or cancer has spread through the serosa of the colon wall to nearby organs, as well as one or more nearby lymph nodes or in tissue near these lymph nodes.

Treatment includes surgery to remove part of the colon and nearby lymph nodes, plus chemotherapy to decrease the risk of cancer returning.

In some instances, such as if surgery cannot completely remove the tumor or some cancer was left behind, radiation may be advised. (Read about this woman’s harrowing stage 3 colon cancer diagnosis story.)

Stage 4 colon cancer

This is when colon cancer has metastasized, spreading from the colon to distant parts of the body. It too is divided into three subcategories, based on how far the cancer has spread.

The NCI defines each type of colon cancer in stage 4 as follows:

Stage 4A: Cancer has spread to a distant area or organ, such as the liver, lung, ovary, or a distant lymph node.

Stage 4B: Cancer has spread to more than one distant area or organ.

Stage 4C: Cancer has spread to the tissue that lines the wall of the abdomen and may have spread to other areas or organs.

Surgery is not a cure in stage 4, but it can be used to remove cancer in the colon, lymph nodes, as well as other lesions from where the cancer spread.

Depending on the number and size of tumors, chemotherapy may be given before and/or after surgery. Radiation may also be used. (Don’t miss this man’s stage 4 colon cancer survival story.)

Tests for identifying colon cancer

There are several different tests to diagnose colon cancer:

Biopsy: A doctor removes a small piece of tissue and sends it to a lab that will analyze it for cancer.

Diagnostic colonoscopy: A thin, flexible tube allows the doctor to visualize the colon and rectum, and can biopsy any polyps found.

Imaging tests: CT, CAT, ultrasound, and MRI tests can look for cancer that has spread to lymph nodes or other tissues or organs in your body.

Survival rate

The NCI’s Surveillance, Epidemiology, and End Results (SEER) database tracks survival rates for colon cancer. It doesn’t group cancer by stages but instead looks at how far the cancer has spread.

Using SEER data, the ACS estimates five-year colon cancer rates for U.S. adults as follows:

• Localized cancer: If the cancer has not spread past the colon, the five-year survival rate is 91 percent.
• Regional cancer: If it has spread to nearby lymph nodes or tissues, the five-year survival rate is 72 percent.
• Distant cancer: If it metastasized to distant lymph nodes or organs like the liver or lungs, the five-year survival rate is 14 percent.

(Here’s what you need to know about millennials and colon cancer.)

Limits of the staging system

Staging is important—it’s the main language that doctors use to speak to one another, understand, and rationalize treatment, says Emmanouil Pappou, MD, colorectal surgeon at Memorial Sloan Kettering Cancer Center in New York City. But cancer doesn’t always follow staging rules.

“Cancer doesn’t read textbooks,” says Dr. Pappou. Though it’s true that colon cancer detected in earlier stages has better prognosis in terms of response to treatment and survival, stage 4 colon cancer isn’t definitely life-threatening. (Don’t miss how this woman is defying her stage 4 colon cancer prognosis.)

It’s important to have a thorough conversation with your doctor about the best treatment for your specific tumor and its molecular profile so that you can get the best care possible.

Next, here are the best colonoscopy prep tips from doctors.