Office of Women's Health

Facts About Colorectal Cancer

What is colorectal cancer?

Colorectal cancer is cancer of the colon or rectum. Most types of colorectal cancer begin with polyps (grape-shaped growths on the lining of the colon and rectum). Removing a polyp early may prevent it from becoming cancer. Polyps are very common in people older than 50 years of age and usually are benign (not cancerous), but some polyps can slowly develop over the years into cancer.

What are the symptoms of colorectal cancer?

Colorectal cancer begins in the digestive system and symptoms may differ depending on where the cancer starts. In its early stages, colorectal cancer often has no symptoms, which is why screening tests are important. People who have symptoms may have a change in bowel habits, diarrhea, constipation or a feeling that the bowel does not empty completely. They also may experience bright red or very dark blood in the stool, stools that are narrower than normal, discomfort in the abdomen including frequent gas pains, bloating, fullness or cramps, weight loss with no known reason, constant and extreme tiredness, vomiting and anemia (low iron in the blood).

Some of these symptoms can be caused by other conditions. Talk with your health care provider if you think you are having any of these symptoms.

Who should be concerned about colorectal cancer?

While it does not get the attention of other cancers, colorectal cancer is the third leading cause of cancer (excluding skin cancer) in the United States and the second leading cause of cancer-related deaths. Risks factors include:

  • Age: Chances of developing colorectal cancer increase after age 50. More than 90 percent of people diagnosed with colorectal cancer are older than 50.
  • Personal history of colorectal cancer: If you have had colorectal cancer, even though it has been completely removed, you are more likely to develop new cancers in the colon and rectum.
  • A personal history of colorectal polyps: If you have had an adenomatous-type polyp, you are at increased risk for developing colorectal cancer, especially if the polyps are large or if there are many of them.
  • A personal history of chronic inflammatory bowel disease (IBD): If you have IBD, including ulcerative colitis or Crohn's Disease, you should begin having a screening colonoscopy eight to 12 years after being diagnosed.
  • A family history of colorectal cancer: Some cancers “run in the family” because something in the environment has contributed to the development of cancer and/or because certain family members were born with or inherited an increased susceptibility to cancer.
  • Unhealthy lifestyle choices: High fat diet, lack of physical activity, obesity, smoking and heavy use of alcohol all play a role in colorectal cancer.

Colorectal cancer is sometimes called a silent killer because in the early stages a person will often have no symptoms. Screening tests are one of the most powerful weapons in preventing colorectal cancer. This is because polyps, or growths, can be detected and removed before they have the chance to turn into cancer. Screening also can result in finding colorectal cancer early, when it is highly curable.

What screening tests are available to help detect colorectal cancer?

There are several different screening tests that can be used to find polyps or colorectal cancer. Each one can be used alone; sometimes they are used in combination. Talk to your doctor about which test(s) is right for you and how often you should be tested. For those of average risk, screening tests usually begin at age 50.

  • Fecal occult blood test (FOBT) - checks for hidden blood in the stool. Sometimes cancers or polyps can bleed and this test is used to pick up small amounts of bleeding. People having this test will receive a kit with instructions from the doctor on how to take a stool sample. The kit is returned to the doctor’s office and sent to a medical lab for testing. This test is not diagnostic for cancer; other follow-up procedures need to be done to find the source of the bleeding because the blood also may indicate other gastrointestinal problems.
  • Flexible sigmoidoscopy - an exam where a health care provider uses a sigmoidoscope, a tube with a light on the end to look at the rectum and lower part of the colon where most tumors appear. Because the sigmoidoscope is only around 2 feet long, the doctor is able to see the entire rectum, but less than half of the colon, with this procedure.
  • Colonoscopy - also uses a hollow, lighted tube called a colonoscope to inspect the entire colon. If polyps are found, they can be biopsied or removed. This test is recommended every 10 years after age 50, or as a follow-up to a positive screening test.
  • Double contrast barium enema (DCBE) - a series of X-rays of the colon and rectum. First, an enema with barium is given to outline the colon and rectum on the X-rays.
  • Digital rectal exam - a health care provider inserts a lubricated, gloved finger into the rectum to feel for any problem areas. This test should be done every year in conjunction with other screening tests (flexible sigmoidoscopy, colonoscopy or DCBE).

What are treatment options for colorectal cancer?

Treatment for colorectal cancer depends mostly on the size, location and extent of the tumor, as well as a person's overall health. Surgery to remove the tumor is the most common treatment for colorectal cancer. Chemotherapy and radiation therapy also may be used to kill cancer cells. With new surgical techniques, treatment rarely requires a colostomy (an opening into a "bag" for passage of bowel movements).

How can I reduce my risk for colon cancer?

  • Screening is the most powerful tool in prevention – regular screening should begin after 50 years of age.
  • Eat plenty of fruits, vegetables and whole grain foods.
  • Limit the intake of high-fat foods.
  • Be physically active with at least 30 minutes of exercise on five or more days of the week.
  • Maintain a healthy weight.
  • Know your family's cancer history.

More information about colorectal cancer can be obtained by contacting:

National Cancer Institute
800-4-CANCER (800-422-6237)

U.S. Centers for Disease Control and Prevention