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      Risk of colorectal cancer seven years after flexible sigmoidoscopy screening: randomised controlled trial

      , 1 , 2 , 1 , 3 , 1 , 4 for the Norwegian Colorectal Cancer Prevention Study Group

      BMJ : British Medical Journal

      BMJ Publishing Group Ltd.

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          Objective To determine the risk of colorectal cancer after screening with flexible sigmoidoscopy.

          Design Randomised controlled trial.

          Setting Population based screening in two areas in Norway—city of Oslo and Telemark county (urban and mixed urban and rural populations).

          Participants 55 736 men and women aged 55-64 years.

          Intervention Once only flexible sigmoidoscopy screening with or without a single round of faecal occult blood testing (n=13 823) compared with no screening (n=41 913).

          Main outcome measures Planned end points were cumulative incidence and mortality of colorectal cancer after 5, 10, and 15 years. This first report from the study presents cumulative incidence after 7 years of follow-up and hazard ratio for mortality after 6 years.

          Results No difference was found in the 7 year cumulative incidence of colorectal cancer between the screening and control groups (134.5 v 131.9 cases per 100 000 person years). In intention to screen analysis, a trend towards reduced colorectal cancer mortality was found (hazard ratio 0.73, 95% confidence interval 0.47 to 1.13, P=0.16). For attenders compared with controls, a statistically significant reduction in mortality was apparent for both total colorectal cancer (hazard ratio 0.41, 0.21 to 0.82, P=0.011) and rectosigmoidal cancer (0.24, 0.08 to 0.76, P=0.016).

          Conclusions A reduction in incidence of colorectal cancer with flexible sigmoidoscopy screening could not be shown after 7 years’ follow-up. Mortality from colorectal cancer was not significantly reduced in the screening group but seemed to be lower for attenders, with a reduction of 59% for any location of colorectal cancer and 76% for rectosigmoidal cancer in per protocol analysis, an analysis prone to selection bias.

          Trial registration Clinical trials NCT00119912.

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          Most cited references 17

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          Colonoscopy in colorectal-cancer screening for detection of advanced neoplasia.

          Recommendations for colorectal-cancer screening are based solely on age and family history of cancer, not sex. We performed a cross-sectional analysis of the data from a large colonoscopy-based screening program that included 50,148 participants who were 40 to 66 years of age. People 40 to 49 years of age were eligible only if they had a family history of cancer of any type. Of the 43,042 participants 50 to 66 years of age, 13.3% reported a family history of colorectal cancer, as did 66.3% of the 7106 participants who were 40 to 49 years of age. We defined advanced neoplasia as cancer or adenoma that was at least 10 mm in diameter, had high-grade dysplasia, or had villous or tubulovillous histologic characteristics, or any combination thereof. We used multivariate logistic regression to identify associations between participants' characteristics and advanced neoplasia in a primary (or derivation) data set, and we confirmed the associations in a secondary (or validation) data set. Advanced neoplasia was detected in 2553 (5.9%) participants 50 to 66 years of age and in 243 (3.4%) participants 40 to 49 years of age. The rate of complications during colonoscopy was 0.1%, and no participants died. In the validation set, a logistic-regression model showed that male sex was independently associated with advanced neoplasia (adjusted odds ratio, 1.73; 95% confidence interval, 1.52 to 1.98; P<0.001). In each age group (40 to 49 years, 50 to 54 years, 55 to 59 years, and 60 to 66 years), the number of persons who would have to undergo colorectal-cancer screening in order to detect one advanced neoplasia was significantly lower in men than in women (23 vs. 36, 17 vs. 28, 12 vs. 22, and 10 vs. 18, respectively). We detected advanced neoplasia at a significantly higher rate in men than in women, which may warrant refinement of the screening recommendations for colorectal cancer. Copyright 2006 Massachusetts Medical Society.
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             YOH ISHIGURO (1972)
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              Risk of developing colorectal cancer following a negative colonoscopy examination: evidence for a 10-year interval between colonoscopies.

              Limited evidence exists to guide the optimal frequency of repeat endoscopic examination for colorectal cancer screening after a negative colonoscopy. To determine the duration and magnitude of the risk of developing colorectal cancer following performance of a negative colonoscopy. Population-based retrospective analysis of individuals whose colonoscopy evaluations did not result in a diagnosis of colorectal neoplasia. Patients who had been evaluated between April 1, 1989, and December 31, 2003, were identified using Manitoba Health's physician billing claims database (N = 35 975). Standardized incidence ratios (SIRs) were calculated to compare colorectal cancer incidence in our cohort with colorectal cancer incidence in the provincial population. Stratified analysis was performed to determine the duration of the reduced risk. Patients with a history of colorectal cancer prior to the index colonoscopy, inflammatory bowel disease, resective colorectal surgery, and lower gastrointestinal endoscopy within the 5 years before the index colonoscopy were excluded. Cohort members were followed up from the time of the index colonoscopy until diagnosis of colorectal cancer, death, out-migration from Manitoba, or end of the study period on December 31, 2003. Incidence of colorectal cancer. A negative colonoscopy was associated with SIRs of 0.69 (95% confidence interval [CI], 0.59-0.81) at 6 months, 0.66 (95% CI, 0.56-0.78) at 1 year, 0.59 (95% CI, 0.48-0.72) at 2 years, 0.55 (95% CI, 0.41-0.73) at 5 years, and 0.28 (95% CI, 0.09-0.65) at 10 years. The proportion of colorectal cancer located in the right side of the colon was significantly higher in the colonoscopy cohort than the rate in the Manitoba population (47% vs 28%; P<.001). The risk of developing colorectal cancer remains decreased for more than 10 years following the performance of a negative colonoscopy. There is a need to improve the early detection rate of right-sided colorectal neoplasia in usual clinical practice.

                Author and article information

                Role: professor
                Role: professor
                Role: professor
                Role: physician and researcher
                BMJ : British Medical Journal
                BMJ Publishing Group Ltd.
                29 May 2009
                : 338
                [1 ]Norwegian Colorectal Cancer Prevention (NORCCAP) Centre, Cancer Registry of Norway, Montebello, NO-0310 Oslo, Norway
                [2 ]Department of Medicine, Telemark Hospital, NO-3710 Skien, Norway
                [3 ]School of Pharmacy, University of Oslo, NO-0316 Oslo
                [4 ]Department of Gastroenterology, Rikshospitalet University Hospital, NO-0027 Oslo
                Author notes
                Correspondence to: G Hoff, Cancer Registry of Norway, P O Box 5313 Majorstuen, 0304 Oslo, Norway  hofg@
                © Hoff et al 2009

                This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                Clinical Trials (Epidemiology)
                Epidemiologic Studies
                Colon Cancer
                Screening (Oncology)
                Surgical Diagnostic Tests
                Gastrointestinal Surgery
                General Surgery
                Screening (Epidemiology)
                Screening (Public Health)



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