News | December 17, 2008

Study Says Colonoscopy More Likely to Miss Cancer on Right Side of Colon

December 17, 2008 - A study released this week in the Annals of Internal Medicine found that colonoscopy is associated with lower death rates from colorectal cancer, however, the procedure missed lesions more often on the right side of the colon versus the left side.

The study highlights the importance of seeking a qualified gastrointestinal endoscopist to perform a thorough colonoscopy and that patients must take the bowel prep as directed by their physician allowing for a clear view of the colon to detect lesions. The American Society for Gastrointestinal Endoscopy (ASGE), representing the specialists in colorectal cancer screening, recommends that patients seek out a well-trained gastrointestinal endoscopist to perform a colonoscopy and to ask questions about their qualifications before the procedure.

"Colonoscopy is the gold standard for colorectal cancer screening for its ability to detect and remove polyps before they turn into cancer,” said John L. Petrini, M.D., FASGE, president of the American Society for Gastrointestinal Endoscopy. "While colonoscopy is not a perfect test, this study should not deter anyone from undergoing a colonoscopy for colorectal cancer screening. Approximately 70 percent of the colonoscopies performed in this study were not done by gastroenterologists. Studies have shown that missed lesion rates are higher for internists and family practice physicians doing colonoscopy. We urge patients to log on to www.asge.org to find a qualified, expertly-trained gastrointestinal endoscopist to perform their colonoscopy and to ask questions about their qualifications."

Study participants included patients with colorectal cancer that was diagnosed between 1996 and 2001 in the province of Ontario, Canada, and died of colorectal cancer by 2003 (the case patients). Investigators found five individuals for each case patient who were similar but had not died of colon cancer by 2003 (the controls). The study looked at 10,292 case patients and 51,460 controls were identified; 719 case patients (7.0 percent) and 5,031 controls (9.8 percent) had undergone colonoscopy. Compared with controls, case patients were less likely to have undergone any attempted colonoscopy or complete colonoscopy. Complete colonoscopy was strongly associated with fewer deaths from left-sided colorectal cancer (33 percent reduction), but not from right-sided colorectal cancer (1 percent reduction).

For more information: www.asge.com

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