Colonoscopy is considered the gold standard for colon cancer screening because it is the most effective way to detect and prevent colon cancer. A colonoscopy is recommended every 10 years for most people starting at age 50, or earlier for those with a family history or other risk factors.
During a colonoscopy, a doctor will examine the inside of the colon and rectum using a long, flexible, lighted tube. This procedure requires anesthesia and takes about 30 minutes. During a colonoscopy, the doctor is able to visualize the lining of the colon and rectum and take biopsies of abnormal tissue, like polyps, for further testing.
A sigmoidoscopy is a similar procedure, but it only allows the doctor to examine the lower portion of the colon and rectum. While a sigmoidoscopy can be useful for detecting abnormalities in the lower colon, it may miss precancerous polyps or early-stage cancer in the upper portion of the colon. Sigmoidoscopy is not considered to be the gold standard for cancer screening but may be recommended for people who are not able to have a colonoscopy for medical reasons, or as a follow-up to a positive fecal occult blood test (FOBT) or fecal immunochemical test (FIT).
