Sigmoidoscopy, a less-invasive screening procedure that examines the lower portion of the bowel, can reduce the risk of developing colorectal cancer or dying from it, according to the results of a study published in the New England Journal of Medicine.
Colorectal cancer is the second leading cause of cancer death in the United States. The American Cancer Society currently recommends that people at average risk of colorectal cancer begin screening for colorectal cancer at the age of 50. Screening may need to begin at a much earlier age for people with a personal or family history of adenomatous polyps, FAP, HNPCC, colorectal cancer, or chronic inflammatory bowel disease. There are several screening tests available for colorectal cancer, including colonoscopy, sigmoidoscopy, double-contrast barium enema, fecal occult blood tests, fecal immunochemical tests, and stool DNA tests.
Colonoscopy has become the gold standard for colorectal screening because it allows the physician to view the entire colon and rectum and on average, need only be performed every 10 years. However, colonoscopy is a costly, invasive, unpleasant procedure and as a result, many people don’t comply with screening recommendations—in fact, only about 60 percent of Americans undergo screening. This new study shows that flexible sigmoidoscopy, a less-invasive procedure, might be a viable alternative.
Sigmoidoscopy is an outpatient procedure that is performed without anesthesia or pain medication. During the procedure, a physician inserts a thin scope and a tiny camera into the rectum to examine the lower part of the colon. Sigmoidoscopy requires less bowel preparation than colonoscopy and is a fraction of the cost. It examines the lower third of the colon, which is where about half of all polyps and cancers develop.
The study, conducted between 1993 and 2001, included nearly 155,000 people ages 55 to 75 who were randomly assigned to undergo a sigmoidoscopy at the start of the study and again 3 to 5 years later or to receive usual care, which referred to screening by any means if desired or if recommended by a doctor. During the study, any patients with suspicious results were sent for further examination with a colonoscopy.
After about 12 years of follow-up, the sigmoidoscopy group had 21 percent fewer cases of colon cancer and 26 percent fewer deaths from the disease. Of the cancers in that group, 243 were caught by sigmoidoscopy and many others wer discovered as a result of symptoms or other tests. The researchers estimated that 97 more cancers would have been detected had they been using colonoscopy rather than sigmoidoscopy.
There is no doubt that colonoscopy is the superior test and is better for detecting all cancers; however, if patients won’t comply with colonoscopy, then a sigmoidoscopy is better than no screening at all. The researchers concluded that sigmoidoscopy screening was associated with a significant decrease in colorectal cancer incidence and mortality. If people are more likely to comply with sigmoidoscopy screening, then it might present a viable alternative and could improve screening rates.
Schoen RE, Pinsky PF, Weissfeld JL, et al. Colorectal-cancer incidence and mortality with screening flexible sigmoidoscopy. New England Journal of Medicine. Published early online May 21, 2012. http://www.nejm.org/doi/full/10.1056/NEJMoa1114635?query=featured_home