|
Colorectal Cancer Screening
| Key Points for This Section
|  |
Tests are used to screen for different types of cancer.
Some screening tests are used because they have been shown to be helpful both in finding cancers early and decreasing the chance of dying from these cancers. Other tests are used because they have been shown to find cancer in some people; however, it has not been proven in clinical trials that use of these tests will decrease the risk of dying from cancer. Scientists study screening tests to find those with the fewest risks and most benefits. Cancer screening trials also are meant to show whether early detection (finding cancer before it causes symptoms) decreases a person's chance of dying from the disease. For some types of cancer, finding and treating the disease at an early stage may result in a better chance of recovery. Clinical trials that study cancer screening methods are taking place in many parts of the country. Information about ongoing clinical trials is available from the NCI Cancer.gov Web site.
Five tests are commonly used to screen for colorectal
cancer:
Fecal occult blood test
A fecal occult blood test (FOBT) checks stool (solid waste) for blood that can only be seen with a microscope. Small samples of stool are placed on special cards and returned to the doctor or laboratory for testing. Blood in the stool may be a sign of polyps or cancer.
Sigmoidoscopy
Sigmoidoscopy is a procedure to look inside the rectum and sigmoid (lower) colon for polyps, abnormal areas, or cancer. A sigmoidoscope (a thin, lighted tube) is inserted through the rectum into the sigmoid colon. Polyps or tissue samples may be taken for biopsy. A sigmoidoscopy and a digital rectal exam (DRE) may be used together to screen for colorectal cancer.
Barium enema
A barium enema (BE) is a series of x-rays of the lower gastrointestinal tract. A liquid that contains barium (a silver-white metallic compound) is put into the rectum. The barium coats the lower gastrointestinal tract and x-rays are taken. This procedure is also called a lower GI series.
Colonoscopy
Colonoscopy is a procedure to look inside the rectum and colon for polyps, abnormal areas, or cancer. A colonoscope (a thin, lighted tube) is inserted through the rectum into the colon. Polyps or tissue samples may be taken for biopsy.
Digital rectal exam
A digital rectal exam (DRE) is an exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel for lumps or anything else that seems unusual.
Other screening tests are being studied in clinical
trials.
Virtual colonoscopy
Virtual colonoscopy is a procedure that uses a series of x-rays called computed tomography to make a series of pictures of the
colon. A computer puts the pictures together to create detailed images that may
show polyps and anything else that seems unusual on the inside surface of the colon. This test is also called colonography or CT colonography. Clinical trials are comparing
virtual colonoscopy with commonly used colorectal cancer screening tests.
DNA stool test
This test checks DNA in stool cells for genetic changes that may be a sign of colorectal cancer.
Screening clinical trials are taking place in many parts of the country.
Information about ongoing clinical trials is available from the
NCI Cancer.gov Web
site.
 Back to Top
< Previous Section | Next Section > |
