Types of Cancer > Colorectal Cancer > Screening & Detection

Screening & Detection for Colorectal Cancer

Colorectal cancer refers to cancer that starts in the colon or rectum. The colon is a six-foot muscular tube that connects the small intestine to the rectum. The rectum, the lower six inches of the digestive tract, holds stool before it leaves the body. These cancers occur when cells lining the colon or the rectum become abnormal and grow out of control.

Screening for colorectal cancer is important because the early stages of the disease, when it's most curable, do not cause symptoms. Symptoms for colorectal cancer include:

• A change in bowel habits (diarrhea, constipation, narrowing of stool) that lasts beyond a few days
• Continuously feeling the need for a bowel movement, even after doing so
• Rectal bleeding or blood in the stool
• Abdominal pain
• Weakness and tiredness

Methods of screening for colorectal cancer include:

Digital Rectal Exam
A digital rectal exam is performed at annual checkup.

Fecal Occult Blood Test
A fecal occult blood test, also known as a stool blood test, is performed yearly to find hidden blood in the stool. If the test is positive, further tests, such as a colonoscopy, are performed to determine the cause of bleeding.

Flexible Sigmoidoscopy
A sigmoidoscope is a slender, lighted tube that is placed into the lower part of the colon through the rectum, allowing the doctor to look for cancer or polyps. This is a limited procedure, however, allowing a doctor only to see about half of the colon.

Colonoscopy
Many experts recommend men and women undergo a colonoscopy at age 50, with follow-up screenings every five years. People with a family history of colorectal cancer or other risk factors should begin having colonoscopies at an earlier age. During a colonoscopy, the doctor uses a colonoscope (a flexible tube-like device equipped with a miniaturized camera) to view the entire colon and detect small polyps (precancerous growths attached to the wall of the colon). Suspicious polyps are often removed during a colonoscopy and, if necessary, a biopsy is performed on the tissue removed through the colonscope. If allowed to grow undetected, these polyps can grow into malignant tumors.

Barium Enema with Air Contrast
To get high-quality x-rays of the colon, a chalky substance is used to partly fill and open the colon. Air is then pumped in to expand the colon.

For more information about colorectal cancer screening, see the Gastroenterology Services section of this web site.