A study published in the Sept. 19 New England Journal of Medicine provides some of the clearest evidence to date that colonoscopy has advantages over sigmoidoscopy for the prevention of colorectal cancer.
Researchers followed 88,902 study participants for 22 years and found that 1,815 developed colorectal cancer. Investigators estimated that 40 percent of those cancers could have been prevented if all of the patients in the study had received colonoscopy.
"Thanks to colonoscopy, fewer people than ever before are developing or dying from colorectal cancer," said Anil K. Rustgi, MD, AGAF, president of the American Gastroenterological Association (AGA) Institute.
"Gastroenterologists, the specialists who screen for colorectal cancer, are proud of our role in this public health success story," added Ronald J. Vender, MD, FACG, president of the American College of Gastroenterology.
Screening is recommended starting at age 50 for people who are at average risk for colorectal cancer. There are many screening options, including the two used in this study: sigmoidoscopy (every five years), which reaches the lower third of the colon, and colonoscopy (every 10 years), which reaches the entire colon. Read full screening guidelines.
When comparing mortality rates in this study, researchers found that only colonoscopy was associated with reduced death from cancer in the proximal colon—the first part of the colon that physicians can see only via colonoscopy. Promixal colorectal cancer is more common in African Americans than whites1.
"Proximal colorectal cancers are associated with worse survival odds2. Colonoscopy allows gastroenterologists to not only visualize this hard-to-reach area of the body, but to remove pre-cancerous polyps, preventing a deadly disease," said Kenneth K. Wang, MD, FASGE, president of the American Society for Gastrointestinal Endoscopy.
Of the more than 50,000 people expected to die of colorectal cancer in 2013, screening could have saved more than half of them3.
Researchers with the Dana-Farber Cancer Institute, Harvard Medical School, Brigham and Women's Hospital, Massachusetts General Hospital, University of Aberdeen (UK), University of Tokyo Hospital and the National Institutes of Health (National Cancer Institute) analyzed information from the Nurses' Health Study and the Health Professionals Follow-up Study, which gather comprehensive health information from participants every two years. Study citation: Nishihara R, Wu K, Lochhead MB, et al. Long-Term Colorectal-Cancer Incidence and Mortality after Lower Endoscopy. N Engl J Med 2013;369:1095-105.
More information: 1 Am J Gastroenterol. 2005 Mar;100(3):515-23; discussion 514
2 Wong RJ Gen Intern Med. 2010 Nov;25(11):1157-63. DOI: 10.1007/s11606-010-1460-4.
3 ACS: Cancer Prevention & Early Detection Facts & Figures 2013