AGA Institute statement: Data support CT colonography as viable colorectal cancer screening optionSeptember 18, 2008Death from colorectal cancer is highly preventable with effective screening and early detection. Many screening options are available, each with advantages and disadvantages, but half of eligible patients still do not participate in colorectal cancer screening. For that reason, a goal of the American Gastroenterological Association (AGA) Institute is to increase colorectal cancer screening rates and improve public health. The AGA Institute considers colonoscopy the definitive test for colorectal cancer screening and prevention. Colonoscopy is the only test that can both detect cancer at an early curable stage and prevent cancer by removing pre-cancerous polyps. Data published in the Sept. 18, 2008, issue of the New England Journal of Medicinei suggests that computed tomographic (CT) colonography may be another acceptable technology for colorectal cancer screening. The availability of CT colonography could increase screening rates in eligible patients (i.e. asymptomatic patients over the age of 50) who have not participated in other colorectal cancer screening procedures. However, a number of important questions need to be addressed: * Does CT colonography find all possible cancers? These study results showed that CT colonography detected 90 percent of large polyps (>10 mm), a rate on par with traditional colonoscopy. However, CT colonography was less sensitive for small polyps (5 mm to 9 mm), with detection rates as low as 65 percent (5 mm). These small polyps were not removed. It is not clear that leaving small polyps is safe; there are no long-term, adequately controlled studies on the subject. The need to define the natural history and biological significance of small polyps is central to refining colorectal cancer screening, irrespective of modality. This study did not investigate diminutive polyps (<5 mm) and the ability of CT colonography to detect flat lesions remains unanswered. * Will CT colonography be accurate in all settings? Study investigators were highly trained in CT colonography, perhaps increasing the accuracy rate of this test. Standardized, rigorous training and proper technique are essential to ensuring that CT colonography achieves appropriate sensitivity, specificity and performance. * Do patients understand the pros and cons of the available colorectal cancer screening tests? Despite the perception that CT colonography is less invasive than traditional colonoscopy, it requires similar bowel preparation as for a colonoscopy. Patients need to understand that a prep is required for CT colonography, and if a polyp is found, it must be removed through a subsequent colonoscopy. Only colonoscopy can prevent colorectal cancer, by removing pre-cancerous polyps. Patients also need to understand that for most people colorectal cancer screening is not a one-time event and that interval examinations are recommended. According to a study by Thomas F. Imperiale et al.ii, published in the same issue of NEJM, a screening interval of five years or longer is appropriate in patients with a normal colonoscopic exam. Because small (< 5 mm) polyps are not typically reported on CT colonography, a negative exam on CT may not be equivalent to a negative colonoscopy. The optimal interval between CT colonography examinations has yet to be defined. * What are the radiation risks? The potential for harm from radiation is difficult to assess given the uncertainty of true risks from low levels of radiation exposure. However, the ionizing radiation exposure from a single abdominal or chest CT may be associated with elevated risk for DNA damage and cancer formation. The rate of radiation exposure with CT colonography may depend on the machine used and the type of CT colonography (2-D versus 3-D imaging) performed; therefore the methodology for screening must be standardized. For more information about the risk of radiation exposure, read the NIH fact sheet, "What We Know About Radiation." Guided by the principle that gastroenterologists are ideally suited to manage patients with gastrointestinal disorders and that they should be able to utilize any technology that can enable them to provide better patient care, the AGA Institute has taken a leadership role with technologies such as CT colonography. With the best interest of patients in mind, the AGA has monitored this technology, created training standards and will continue to educate those gastroenterologists who wish to provide this procedure to patients. More information about the AGA Institute's work related to CT colonography reimbursement, training and standards can be found at www.gastro.org/ctc. Resources for patients on CT colonography, colonoscopy and colorectal cancer can be found at www.gastro.org/patient. American Gastroenterological Association |
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| Related Colorectal Cancer Current Events and Colorectal Cancer News Articles Colon cancer screening more effective earlier in day, UCLA study finds The effectiveness of a screening colonoscopy may depend on the time of day it is performed. According to a new UCLA study, early-morning colonoscopies yielded more polyps per patient than later screenings, and fewer polyps were found hour by hour as the day progressed. 1 disease, not 1 demographic The Asian continent has nearly four billion people living in 47 different countries, and each of these groups has their own unique set of health issues. But when they come to the United States, they're often lumped into one large demographic: "Asian/Pacific Islander." Study shows unsedated colonoscopy for colorectal cancer screening well accepted by patients Researchers from Taiwan report in a new study that unsedated colonoscopy for primary colorectal cancer screening is well accepted in a majority of patients. M. D. Anderson redefines screening guidelines for breast, cervical and colorectal cancers Drawing on years of experience in cancer research and patient care, The University of Texas M. D. Anderson Cancer Center released today the most comprehensive, risk-based screening guidelines publicly available to date for breast, cervical and colorectal cancers. The bowels of infection Current research suggests that latent cytomegalovirus (CMV) infection may exacerbate inflammatory bowel disease (IBD). The related report by Onyeagocha et al, "Latent cytomegalovirus infection exacerbates experimental colitis," appears in the November 2009 issue of The American Journal of Pathology. How to Lower Costs, Waiting Times for Colonoscopies Colorectal cancer is a leading cause of cancer-related deaths in the United States, leading to over 50,000 fatalities every year. Excess body weight causes over 124,000 new cancers a year in Europe At least 124,000 new cancers in 2008 in Europe may have been caused by excess body weight, according to estimates from a new modelling study. Adding cetuximab to chemotherapy reduces advanced lung cancer death risk by 13 percent Patients with advanced non-small cell lung cancer who are given cetuximab (Erbitux) in addition to chemotherapy are 13% less likely to die than those who receive chemotherapy alone, regardless of which chemotherapy drug cocktail is used, new research finds. They also experience slower disease progression and an increased chance of tumour shrinkage. New blood tests promise simple, cost-effective diagnosis of gastrointestinal cancers Promising results from two new blood tests that can aid in the early identification of patients with gastrointestinal (GI) cancers will be presented at Europe's largest cancer congress. University of Hawaii at Manoa CRCH scientists report adulthood body size associated with cancer risk A team of scientists led by researcher Brenda Hernandez, Ph.D., M.P.H.-an assistant professor at the University of Hawai'i at Mānoa's Cancer Research Center of Hawai'i-has reported that body mass in younger and older adulthood, and weight gain between these life periods, may influence a man's risk for prostate cancer. More Colorectal Cancer Current Events and Colorectal Cancer News Articles |
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