Dataset Information

Relationship between detection of adenomas by flexible sigmoidoscopy and interval distal colorectal cancer.

ABSTRACT:

Background & aims

Low rates of adenoma detection by colonoscopy have been associated with increased rates of interval colorectal cancer. We evaluated the relationship between the rate of adenoma detection by flexible sigmoidoscopy and interval distal colorectal cancer.

Methods

We analyzed data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer screening trial, which used flexible sigmoidoscopy as a colorectal cancer screening modality (46,835 subjects; 66,711 examinations by 93 examiners). An adenoma detection rate was defined for each examiner as the number of examinations that identified adenomas (confirmed by pathology analysis) divided by the total number of screening examinations. Interval cancers were defined as cancers presumed detectable but not detected, which was based on the stage at diagnosis and the elapsed time from screening to diagnosis.

Results

The Prostate, Lung, Colorectal, and Ovarian Cancer study identified 32 interval distal cancers. The incidence of interval cancer for individuals screened by examiners in the lowest quartile of distal adenoma detection (2.0%-7.2%) was 9.0/10,000 examinations, whereas the incidence of interval cancers was lower among individuals whose examiners were in higher quartiles of adenoma detection, ranging from 3.0 to 5.4/10,000 examinations. The odds of interval distal cancer were significantly increased for patients of examiners in the lowest quartile of distal adenoma detection (<7.2%), with an adjusted odds ratio of 2.4 (95% confidence interval, 1.1-5.0; P = .02).

Conclusions

Lower levels of adenoma detection by flexible sigmoidoscopy increase the risk for interval distal cancer. Detection of distal adenomas is a marker of the performance quality of flexible sigmoidoscopy.

SUBMITTER: Rogal SS

PROVIDER: S-EPMC3525787 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Publications

Relationship between detection of adenomas by flexible sigmoidoscopy and interval distal colorectal cancer.

Rogal Shari S SS Pinsky Paul F PF Schoen Robert E RE

Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association 20120816 1

<h4>Background & aims</h4>Low rates of adenoma detection by colonoscopy have been associated with increased rates of interval colorectal cancer. We evaluated the relationship between the rate of adenoma detection by flexible sigmoidoscopy and interval distal colorectal cancer.<h4>Methods</h4>We analyzed data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer screening trial, which used flexible sigmoidoscopy as a colorectal cancer screening modality (46,835 subjects; 66,711 examinati ...[more]

PMID: 22902761

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Project description:BACKGROUND:The benefits of endoscopic testing for colorectal-cancer screening are uncertain. We evaluated the effect of screening with flexible sigmoidoscopy on colorectal-cancer incidence and mortality. METHODS:From 1993 through 2001, we randomly assigned 154,900 men and women 55 to 74 years of age either to screening with flexible sigmoidoscopy, with a repeat screening at 3 or 5 years, or to usual care. Cases of colorectal cancer and deaths from the disease were ascertained. RESULTS:Of the 77,445 participants randomly assigned to screening (intervention group), 83.5% underwent baseline flexible sigmoidoscopy and 54.0% were screened at 3 or 5 years. The incidence of colorectal cancer after a median follow-up of 11.9 years was 11.9 cases per 10,000 person-years in the intervention group (1012 cases), as compared with 15.2 cases per 10,000 person-years in the usual-care group (1287 cases), which represents a 21% reduction (relative risk, 0.79; 95% confidence interval [CI], 0.72 to 0.85; P<0.001). Significant reductions were observed in the incidence of both distal colorectal cancer (479 cases in the intervention group vs. 669 cases in the usual-care group; relative risk, 0.71; 95% CI, 0.64 to 0.80; P<0.001) and proximal colorectal cancer (512 cases vs. 595 cases; relative risk, 0.86; 95% CI, 0.76 to 0.97; P=0.01). There were 2.9 deaths from colorectal cancer per 10,000 person-years in the intervention group (252 deaths), as compared with 3.9 per 10,000 person-years in the usual-care group (341 deaths), which represents a 26% reduction (relative risk, 0.74; 95% CI, 0.63 to 0.87; P<0.001). Mortality from distal colorectal cancer was reduced by 50% (87 deaths in the intervention group vs. 175 in the usual-care group; relative risk, 0.50; 95% CI, 0.38 to 0.64; P<0.001); mortality from proximal colorectal cancer was unaffected (143 and 147 deaths, respectively; relative risk, 0.97; 95% CI, 0.77 to 1.22; P=0.81). CONCLUSIONS:Screening with flexible sigmoidoscopy was associated with a significant decrease in colorectal-cancer incidence (in both the distal and proximal colon) and mortality (distal colon only). (Funded by the National Cancer Institute; PLCO ClinicalTrials.gov number, NCT00002540.).

Project description:IMPORTANCE:Colorectal cancer is a major health burden. Screening is recommended in many countries. OBJECTIVE:To estimate the effectiveness of flexible sigmoidoscopy screening on colorectal cancer incidence and mortality in a population-based trial. DESIGN, SETTING, AND PARTICIPANTS:Randomized clinical trial of 100,210 individuals aged 50 to 64 years, identified from the population of Oslo city and Telemark County, Norway. Screening was performed in 1999-2000 (55-64-year age group) and in 2001 (50-54-year age group), with follow-up ending December 31, 2011. Of those selected, 1415 were excluded due to prior colorectal cancer, emigration, or death, and 3 could not be traced in the population registry. INTERVENTIONS:Participants randomized to the screening group were invited to undergo screening. Within the screening group, participants were randomized 1:1 to receive once-only flexible sigmoidoscopy or combination of once-only flexible sigmoidoscopy and fecal occult blood testing (FOBT). Participants with positive screening test results (cancer, adenoma, polyp ?10 mm, or positive FOBT) were offered colonoscopy. The control group received no intervention. MAIN OUTCOMES AND MEASURES:Colorectal cancer incidence and mortality. RESULTS:A total of 98,792 participants were included in the intention-to-screen analyses, of whom 78,220 comprised the control group and 20,572 comprised the screening group (10,283 randomized to receive a flexible sigmoidoscopy and 10,289 to receive flexible sigmoidoscopy and FOBT). Adherence with screening was 63%. After a median of 10.9 years, 71 participants died of colorectal cancer in the screening group vs 330 in the control group (31.4 vs 43.1 deaths per 100,000 person-years; absolute rate difference, 11.7 [95% CI, 3.0-20.4]; hazard ratio [HR], 0.73 [95% CI, 0.56-0.94]). Colorectal cancer was diagnosed in 253 participants in the screening group vs 1086 in the control group (112.6 vs 141.0 cases per 100,000 person-years; absolute rate difference, 28.4 [95% CI, 12.1-44.7]; HR, 0.80 [95% CI, 0.70-0.92]). Colorectal cancer incidence was reduced in both the 50- to 54-year age group (HR, 0.68; 95% CI, 0.49-0.94) and the 55- to 64-year age group (HR, 0.83; 95% CI, 0.71-0.96). There was no difference between the flexible sigmoidoscopy only vs the flexible sigmoidoscopy and FOBT screening groups. CONCLUSIONS AND RELEVANCE:In Norway, once-only flexible sigmoidoscopy screening or flexible sigmoidoscopy and FOBT reduced colorectal cancer incidence and mortality on a population level compared with no screening. Screening was effective both in the 50- to 54-year and the 55- to 64-year age groups. TRIAL REGISTRATION:clinicaltrials.gov Identifier: NCT00119912.

Project description:BackgroundColorectal cancer (CRC) is the second most prevalent type of cancer in Europe. A single flexible sigmoidoscopy (FS) screening at around the age of 60 years prevents about one-third of CRC cases. However, FS screens only the distal colon, and thus mortality from proximal CRC is unaffected. Computed tomography colonography (CTC) is a highly accurate examination that allows assessment of the entire colon. However, the benefit of CTC testing as a CRC screening test is uncertain. We designed a randomized trial to compare participation rate, detection rates, and costs between CTC (with computer-aided detection) and FS as primary tests for population-based screening.Methods/designAn invitation letter to participate in a randomized screening trial comparing CTC versus FS will be mailed to a sample of 20,000 people aged 58 or 60 years, living in the Piedmont region and the Verona district of Italy. Individuals with a history of CRC, adenomas, inflammatory bowel disease, or recent colonoscopy, or with two first-degree relatives with CRC will be excluded from the study by their general practitioners. Individuals responding positively to the invitation letter will be then randomized to the intervention group (CTC) or control group (FS), and scheduled for the screening procedure. The primary outcome parameter of this part of the trial is the difference in advanced neoplasia detection between the two screening tests. Secondary outcomes are cost-effectiveness analysis, referral rates for colonoscopy induced by CTC versus FS, and the expected and perceived burden of the procedures. To compare participation rates for CTC versus FS, 2,000 additional eligible subjects will be randomly assigned to receive an invitation for screening with CTC or FS. In the CTC arm, non-responders will be offered fecal occult blood test (FOBT) as alternative screening test, while in the FS arm, non-responders will receive an invitation letter to undergo screening with either FOBT or CTC. Data on reasons for participation and non-participation will also be collected.DiscussionThis study will provide reliable information concerning benefits and risks of the adoption of CTC as a mass screening intervention in comparison with FS. The trial will also evaluate the role of computer-aided detection in a screening setting.Trial registrationClinicalTrials.gov Identifier: NCT01739608.

Dataset Information

Relationship between detection of adenomas by flexible sigmoidoscopy and interval distal colorectal cancer.

Background & aims

Methods

Results

Conclusions

Publications

Relationship between detection of adenomas by flexible sigmoidoscopy and interval distal colorectal cancer.

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