Colon Cancer Overview

The human colon is a muscular, tube–shaped organ measuring about 4 feet long. It extends from the end of your small bowel to your anus, twisting and turning through your abdomen (belly).

Colon Cancer Causes

Certain conditions can make it more common for a person to develop colon cancer:

  • A family history of colon cancer
  • Diet: Whether diet plays a role in developing colon cancer remains under debate. The belief that a high–fiber, low–fat diet could help prevent colon cancer has been questioned. Studies do indicate that exercise and a diet rich in fruits and vegetables can help prevent colon cancer.
  • Obesity
  • Cigarette smoking

Colon Cancer Symptoms

Cancer of the colon and rectum can exhibit itself in several ways. If you have any of these symptoms, seek immediate medical help.

You may notice bleeding from your rectum or blood mixed with your stool.

  • People commonly attribute all rectal bleeding to hemorrhoids, thus preventing early diagnosis owing to lack of concern over “bleeding hemorrhoids.”
  • Rectal bleeding may be hidden and chronic and may show up as an iron deficiency anemia.
  • It may be associated with fatigue and pale skin.

If the tumor gets large enough, it may completely or partially block your colon. You may notice the following symptoms of bowel obstruction:

  • Abdominal distension: Your belly sticks out more than it did before without weight gain.
  • Abdominal pain: This is rare in colon cancer. One cause is tearing (perforation) of the bowel. Leaking of bowel contents into the pelvis can cause inflammation (peritonitis) and infection.
  • Unexplained, persistent nausea or vomiting
  • Unexplained weight loss
  • Change in frequency or character of stool (bowel movements)
  • Small–caliber (narrow) or ribbon-like stools
  • Sensation of incomplete evacuation after a bowel movement
  • Rectal pain: Pain rarely occurs with colon cancer and usually indicates a bulky tumor in the rectum that may invade surrounding tissue.

Studies suggest that the average duration of symptoms (from onset to diagnosis) is 14 weeks. There is no association between overall duration of symptoms and the stage of your tumor.


Your best prevention is to detect colon cancer and treat it early in its formation. People who have regular screening for colon cancer, including colonoscopy, and polyp removal, greatly reduce their risk of having a colorectal cancer.

Other things you can do to lower your risk include the following:

  • Quit smoking. Smoking cigarettes has been clearly linked with higher risk of colon cancer (as well as many other conditions).
  • Take an aspirin or baby aspirin every day. Because of potential side effects, this is not recommended for everyone. Talk to your health care provider first.
  • Take a safe dose of folic acid (for example, 1 mg) every day.
  • Engage in physical activity every day.
  • Eat a variety of fruits and vegetables every day.


    By Jose Rodriguez, MD