Colon Cancer Learning Center

  • Enlarge
  • Print
  • Recommend

Colon Cancer


Cancer of the rectum, also called colorectal or colon cancer, is a cancer that develops in the colon or rectum. Your rectum is located in the last few inches of the colon. Colon cancer normally begins as small polyps. Most cases of colon polyps are benign, but some may become cancerous, so all instances of polyps are tested for the presence of cancer cells. Some people experience symptoms of colon cancer, although many people do not.

The exact cause of colon cancer isn’t known; however, doctors have concluded that certain factors increase your risk of developing it, including:

  • family history of colorectal cancer
  • polyps in the colon
  • a diet that is high in fat
  • chronic ulcerative colitis

What are the Symptoms of Colon Cancer?

Most people with colon cancer will not know they have the condition until they are screened for it. This is because most cases have no symptoms. However, people who do experience symptoms may have the following:

  • constipation
  • bleeding from the anus
  • loose stool or diarrhea
  • dark patches in the stool
  • pencil-shaped stool
  • abdominal discomfort
  • unexplained fatigue
  • loss of appetite
  • weight loss
  • pelvic pain

How is Colon Cancer Diagnosed?

The symptoms of colon cancer mimic other conditions, so it’s best to see a physician if you have any concerns.

If colon cancer is suspected, your physician will give you a lower GI (lower gastrointestinal series) with a barium enema. This is an X-ray of your colon and rectum given after an enema containing a barium dye has been administered.

Your doctor might also suggest you have a colonoscopy. A colonoscopy is used to confirm the presence of colon cancer and to locate any polyps or tumors in the colon or rectum.

When a lower GI is performed, any abnormalities found will appear as dark shadows on the X-ray, so a colonoscopy is often used to confirm what abnormalities are present. A colonoscopy is also used to remove polyps.

What are the Stages of Colon Cancer?

If cancer is detected it can fall into 5 stages.

Stage 0

Stage 0 is the earliest stage of a cancer diagnosis. Abnormal cells are found in the inner walls of the colon. These cells could become cancerous and spread beyond this point.

Stage I

Stage I, also called Dukes A colon cancer, is a cancer that’s spread beyond the inner walls of the colon and into the muscle layers in the colon.

Stage II

At this stage of cancer, the tumor extends past the muscular wall of the colon and into the outer layer of the wall, which is called the serosa.

Stage III

In stage III, the cancer has spread beyond the serosa and into the lymph nodes. The lymph nodes are small nodules that store and produce cells that fight infection in the body. In this stage, the cancer may also form tissue around or near the lymph node gland.

Stage IV

This is the most advanced stage of colon cancer. At this stage, the cancer has spread into various organs in the body, such as the lungs or brain.

How is Colon Cancer Treated?

There are four main treatments given to people with colon cancer— surgery, chemotherapy, radiation therapy, and counseling. Depending on what stage of colon cancer you have, you may be given a choice between several treatments or you may be advised to have more than one. Even after treatment, the cancer may return. Currently there aren’t any ways to determine if this will occur.

What is the Outlook for Colon Cancer?

After being treated for colon cancer, you return to your doctor for follow-up care. During your appointments, your doctor will monitor your symptoms and order an imaging scan and blood tests.

Content licensed from:

Written by: April Khan and Matthew Solan
Published on Jul 25, 2012
Medically reviewed by George Krucik, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
Condition & Treatment Search
Symptom Search
Drug Search




Discounts & Benefits

From companies that meet the high standards of service and quality set by AARP.

Member Benefits Outback

Members save 15% on lunch and dinner every day at Outback Steakhouse.

Member Benefits AT&T Wireless Cell Phone

Members save 10% on monthly usage charges for qualified AT&T wireless plans.

Member Benefit Swipe Save Discount

Members can find current offers on select items from Family Dollar at

Member Benefits

Join or renew today! AARP members receive exclusive member benefits & affect social change.

Rewards for Good

Your Points Balance:

Learn More

Earn points for completing free online activities designed to enrich your life.

Find more ways to earn points

Redeem your points to save on merchandise, travel, and more.

Find more ways to redeem points


African American, Asian Community Page

AARP In Your Corner

Visit Black Community, Español  and Asian Community pages.

AARP Drivers Safety logo

Driver Safety Program

Register at a location near you to keep your driving skills sharp. 

Create the Good

Create The Good 

Find opportunities to volunteer in your neighborhood. 

AARP Drive to End Hunger Logo

Drive to End Hunger

NASCAR champ Jeff Gordon teams up with AARP Foundation.