Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Quick Facts

Colon Cancer

(Colorectal Cancer)

By

The Manual's Editorial Staff

Last full review/revision Mar 2021| Content last modified Mar 2021
CLICK HERE FOR THE PROFESSONAL VERSION
Get the full details
Topic Resources

Your colon is your large intestine. Your rectum is a pouch at the end of your colon where stool is stored until you pass it.  

Locating the Large Intestine

Locating the Small Intestine

What is colon cancer?

Cancer Overview of Cancer Cancer is the out-of-control growth of cells in your body. Cells are the tiny building blocks of your body. Cells specialize in what they do. For example, your intestines have muscle cells to... read more is the out-of-control growth of cells in your body. Cells are the tiny building blocks of your body. Cells specialize in what they do. Different organs are made of different kinds of cells. Almost any kind of cell can become cancerous.

  • The most common symptoms are bleeding when you pass stool and feeling tired and weak

  • Everyone over the age of 45 should be screened for colorectal cancer

  • Colon cancer caught early is more curable

  • Doctors usually remove the cancer with surgery

What causes colon cancer?

What are the symptoms of colon cancer?

Colon cancer grows slowly and doesn't cause symptoms for a long time. Symptoms may include:

  • Feeling weak and tired—in some people this is the only symptom

  • Belly pain

  • Constipation (trouble passing stool)

  • Blood in your stool

  • Feeling like your rectum isn’t completely empty after passing stool

How can doctors tell if I have colon cancer?

If you have symptoms that doctors think might be from colon cancer, they usually do:

If colonoscopy shows cancer, then doctors usually do:

How do doctors screen for colon cancer?

Because colon cancer is so common, doctors recommend screening tests to look for cancer before it causes symptoms. Screening for colon cancer usually begins at age 45 but earlier if you have certain high risk factors. Talk to your doctor about when you need to start screening.

Screening tests include:

How do doctors treat colon cancer?

Doctors treat colon cancer with:

Understanding Colostomy

In a colostomy, the large intestine (colon) is cut. The part that remains connected to the colon is brought to the skin surface through an opening that has been formed. The part is then stitched to the skin. Stool passes through the opening and into a disposable bag.

Understanding Colostomy

For rectal cancer, doctors do:

If doctors have to take out your rectum, you usually will need a colostomy. With a colostomy, doctors attach the end of your colon to an opening in the wall of your belly. Your stool comes out of this opening into a plastic colostomy bag. The bag is stuck onto your belly with adhesive and you change it when it fills up.

After your treatment, doctors will continue to care for you and check on your health with regular testing, such as:

NOTE: This is the Consumer Version. DOCTORS: CLICK HERE FOR THE PROFESSONAL VERSION
CLICK HERE FOR THE PROFESSONAL VERSION
Others also read
Test your knowledge
Musculoskeletal Pain
The most common symptom in musculoskeletal disorders is pain. Pain varies widely from mild to severe, and from short-lived and acute to long-term and chronic. Pain may affect a small or large area of the body. Which of the following is the most common cause of musculoskeletal pain?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
TOP