What is colon cancer?

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was reviewed on December 13, 2022.

The colon and the rectum make up the large intestine. Cancer of the colon and/or rectum is referred to as colorectal cancer, the fourth most common cancer in the United States. About two-thirds of the 106,590 cases of colorectal cancers diagnosed each year develop in the colon.

Colon cancer occurs when cells in that vital organ mutate and grow out of control. The cancer may also develop when growths on the inside of the colon, called polyps, grow and become cancerous.

The risk of colon cancer increases with age. The average age of a patient diagnosed with this disease is 68. Men have a higher risk than women, and African Americans have a higher risk than other racial demographics.

In order to help reduce the risk of colon cancer and help prevent the disease or catch it early, experts recommend regular examinations and lifestyle changes.

Colon cancer causes and risk factors

The exact cause of colon cancer is not known, but certain factors are linked to the disease, such as genetics: People with a family history of colon cancer, Gardner syndrome or certain hereditary cancer syndromes (such as Lynch syndrome or familial adenomatous polyposis) have a higher risk, which also increases with age. Other known risk factors for colon cancer include:

  • Diet
  • Smoking
  • Alcohol use
  • Sedentary lifestyle
  • Obesity
  • Diabetes
  • Inflammatory bowel disease (Crohn's disease or ulcerative colitis)

Learn more about risk factors for colorectal cancer

Signs and symptoms of colon cancer

Colon cancer may show no obvious signs or symptoms in early stages. As the cancer develops, colorectal cancer symptoms may include changes in bowel movements, including frequency, constipation and consistency (loose or watery stools). Other signs and symptoms of colon cancer include:

  • Fatigue
  • Weight loss
  • Blood in the stool
  • Bleeding from the rectum
  • Abdominal pain
  • Bloating
  • Difficulty emptying the bowels

If the cancer spreads, or metastasizes, to other parts of the body, symptoms may develop depending on where in the body the cancer is located. Symptoms of metastatic colon cancer may include:

  • Persistent cough
  • Fatigue
  • Bone pain
  • Shortness of breath
  • Loss of appetite
  • Jaundice
  • Swelling in the hands and feet
  • Changes in vision or speech

Learn more about colorectal cancer symptoms

Types of colon cancer

About 95 percent of all colon cancers are adenocarcinoma. These tumors typically start as a growth in the lining of the colon called a polyp. Colon polyps may be removed during a routine colonoscopy before they have a chance to develop into cancer.

Other types of colon cancer include:

Learn more about colorectal cancer types

Diagnosing and staging colon cancer

A variety of imaging and laboratory tests are used to visualize the digestive system and diagnose colon cancer and determine the stage of the disease. These tools and procedures include:

These screening tests may also be used to monitor the patient's response to treatment.

Learn more about colorectal cancer stages, which includes bowel, rectal and colon cancer, and diagnostic procedures

Colon cancer treatments

Colorectal cancer treatment may depend on where the disease is found, as well as its stage and the extent to which it has developed. Treatment options include:

Learn more about colon cancer treatment by stage.

Integrative care for colon cancer

The symptoms of colon cancer and side effects of treatment may impact the patient's quality of life. At City of Hope, our team of colon cancer experts not only focus on treating the disease with a wide range of tools and technologies, but we also provide integrative care services to help manage side effects. These services may include:

Learn more about integrative care

Get expert advice and care

Understanding when symptoms are a sign of something serious and either diagnosing the disease or confirming a previous diagnosis require expertise from professionals trained and experienced in treating colon cancer. At City of Hope, our colon cancer experts treat all stages and types of the disease.

Search our cancer doctors and experts

Expert cancer care

is one call away.
appointments in as little as 24 hrs.

Assess your cancer risk and take control

Try it now