Although the rates of colon cancer have decreased over the last 10 years, Durado Brooks, M.D., lead author of the American Cancer Society report in the April 1, 2008 "American Family Physician," colon cancer remained the second leading cause of cancer death in 2007. Colonoscopies check the length of the intestine for polyps, small fleshy growths that can turn cancerous over a period of seven to 15 years. Removing pre-cancerous or cancerous polyps decreases the risk of death from colon cancer.
Preparation
Preparation for colonoscopy is essential to visualization of the colon interior. Without preparation, polyps could be overlooked. The presence of fecal residue interferes with visualization and increases the chance of missing advanced disease. An experienced practitioner can visualize the entire colon in 90 percent of cases, the Merck Manual reports.
Time
Medical personnel who took at least six minutes to examine the colon found nearly three times as many cancers and almost twice as many advanced cancers as those whose withdrawal time took less than six minutes, according to the U.S. Multi-Society Task Force on Colorectal Cancer.
Polyp Types
Most polyps fall into one of two categories: adenomatous or hyperplastic. While hyperplastic polyps rarely--if ever--turn cancerous, adenomatous polyps can develop into colon cancer. Having three or more polyps and having polyps as large or larger than 1 cm also increases the risk of developing cancer.
Complications
Polypectomy during colonoscopy slightly increases the risk of complications. The risk of perforation of the colon increases from 0.1 percent in colonoscopy alone to 0.3 percent in colonoscopy with polypectomy. The risk of bleeding, negligible in colonoscopy without polypectomy, increases to 1.5 percent with polypectomy. Incomplete removal of cancerous polyps may result in an increased risk of recurrent cancer.
Follow Up
Follow-up recommendations after polypectomy vary depending on the number and size of polyps found, if any. If no more than one or two polyps less than 0.4 inches in diameter are removed, repeat colonoscopy in five to 10 years may be recommended, depending on other risk factors, MayoClinic.com states. A larger number of polyps, larger polyps or polyps with certain characteristics may necessitate a repeat colonoscopy in three to five years. Discovery of large polyps may require three to six month follow-up.
