Screening for colorectal neoplasia with faecal occult blood testing compared with flexible sigmoidoscopy directly in a 55-56 years' old population

Screening for Colorectal Cancer: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force

IMPORTANCE

Colorectal cancer (CRC) remains a significant cause of morbidity and mortality in the US.

OBJECTIVE

To systematically review the effectiveness, test accuracy, and harms of screening for CRC to inform the US Preventive Services Task Force.

DATA SOURCES

MEDLINE, PubMed, and the Cochrane Central Register of Controlled Trials for relevant studies published from January 1, 2015, to December 4, 2019; surveillance through March 26, 2021.

STUDY SELECTION

English-language studies conducted in asymptomatic populations at general risk of CRC.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently appraised the articles and extracted relevant study data from fair- or good-quality studies. Random-effects meta-analyses were conducted.

MAIN OUTCOMES AND MEASURES

Colorectal cancer incidence and mortality, test accuracy in detecting cancers or adenomas, and serious adverse events.

RESULTS

The review included 33 studies (n = 10 776 276) on the effectiveness of screening, 59 (n = 3 491 045) on the test performance of screening tests, and 131 (n = 26 987 366) on the harms of screening. In randomized clinical trials (4 trials, n = 458 002), intention to screen with 1- or 2-time flexible sigmoidoscopy vs no screening was associated with a decrease in CRC-specific mortality (incidence rate ratio, 0.74 [95% CI, 0.68-0.80]). Annual or biennial guaiac fecal occult blood test (gFOBT) vs no screening (5 trials, n = 419 966) was associated with a reduction of CRC-specific mortality after 2 to 9 rounds of screening (relative risk at 19.5 years, 0.91 [95% CI, 0.84-0.98]; relative risk at 30 years, 0.78 [95% CI, 0.65-0.93]). In observational studies, receipt of screening colonoscopy (2 studies, n = 436 927) or fecal immunochemical test (FIT) (1 study, n = 5.4 million) vs no screening was associated with lower risk of CRC incidence or mortality. Nine studies (n = 6497) evaluated the test accuracy of screening computed tomography (CT) colonography, 4 of which also reported the test accuracy of colonoscopy; pooled sensitivity to detect adenomas 6 mm or larger was similar between CT colonography with bowel prep (0.86) and colonoscopy (0.89). In pooled values, commonly evaluated FITs (14 studies, n = 45 403) (sensitivity, 0.74; specificity, 0.94) and stool DNA with FIT (4 studies, n = 12 424) (sensitivity, 0.93; specificity, 0.85) performed better than high-sensitivity gFOBT (2 studies, n = 3503) (sensitivity, 0.50-0.75; specificity, 0.96-0.98) to detect cancers. Serious harms of screening colonoscopy included perforations (3.1/10 000 procedures) and major bleeding (14.6/10 000 procedures). CT colonography may have harms resulting from low-dose ionizing radiation. It is unclear if detection of extracolonic findings on CT colonography is a net benefit or harm.

CONCLUSIONS AND RELEVANCE

There are several options to screen for colorectal cancer, each with a different level of evidence demonstrating its ability to reduce cancer mortality, its ability to detect cancer or precursor lesions, and its risk of harms.

Effect of once-only flexible sigmoidoscopy screening on the outcomes of subsequent faecal occult blood test screening

OBJECTIVE

To investigate the outcomes of biennial guaiac faecal occult blood test (gFOBT) screening after once-only flexible sigmoidoscopy (FS) screening.

METHODS

Between 1994 and 1999, as part of the UK FS Screening Trial (UKFSST), adults aged 55-64 were randomly allocated to an intervention group (offered FS screening) or a control group (not contacted). From 2006, a subset of UKFSST participants (20,895/44,041 intervention group; 41,497/87,149 control group) were invited to biennial gFOBT screening by the English Bowel Cancer Screening Programme. We analysed gFOBT uptake, test positivity, yield of colorectal cancer (CRC), and positive predictive value (PPV) for CRC, advanced adenomas (AAs), and advanced colorectal neoplasia (ACN: AA/CRC).

RESULTS

Uptake of gFOBT at first invitation was 1.9% lower (65.7% vs. 67.6%, p < 0.01) among intervention versus control group participants. Positivity was 0.4% lower (2.0% vs. 2.4%, p < 0.01) and CRC yield was 0.08% lower (0.19% vs. 0.27%, p = 0.14). PPVs were also lower in the intervention versus control group, at 10.3% vs. 12.3% ( p = 0.44) for CRC, 22.7% vs. 31.4% ( p < 0.01) for AA, and 33.0% vs. 43.7% ( p < 0.01) for ACN. Among those who refused FS ( n = 5532), gFOBT uptake at first invitation was 47.7%, CRC yield was 0.25%, and PPV for ACN was 46.2%. Among FS attenders ( n = 15,363), uptake was 72.2%, CRC yield was 0.18%, and PPV for ACN was 27.9%.

CONCLUSIONS

Uptake, positivity and PPV of gFOBT screening were reduced following prior offer of FS screening. However, a quarter of FS screened participants receiving a diagnostic examination after positive gFOBT were diagnosed with ACN.

Colorectal Cancer Screening in Average Risk Populations: Evidence Summary

Introduction. The objectives of this systematic review were to evaluate the evidence for different CRC screening tests and to determine the most appropriate ages of initiation and cessation for CRC screening and the most appropriate screening intervals for selected CRC screening tests in people at average risk for CRC. Methods. Electronic databases were searched for studies that addressed the research objectives. Meta-analyses were conducted with clinically homogenous trials. A working group reviewed the evidence to develop conclusions. Results. Thirty RCTs and 29 observational studies were included. Flexible sigmoidoscopy (FS) prevented CRC and led to the largest reduction in CRC mortality with a smaller but significant reduction in CRC mortality with the use of guaiac fecal occult blood tests (gFOBTs). There was insufficient or low quality evidence to support the use of other screening tests, including colonoscopy, as well as changing the ages of initiation and cessation for CRC screening with gFOBTs in Ontario. Either annual or biennial screening using gFOBT reduces CRC-related mortality. Conclusion. The evidentiary base supports the use of FS or FOBT (either annual or biennial) to screen patients at average risk for CRC. This work will guide the development of the provincial CRC screening program.

The sensitivity, specificity, predictive values, and likelihood ratios of fecal occult blood test for the detection of colorectal cancer in hospital settings

Objectives

To study the performance of a single test using two fecal occult blood tests with colonoscopy for the detection of colorectal cancer (CRC) for the first time in Saudi Arabia to determine possible implications for the anticipated colorectal screening program.

Materials and methods

We compared the performance of guaiac and immunochemical fecal occult blood tests for the detection of CRC among patients of 50–74 years old attending two hospitals in the Eastern Region of Saudi Arabia. Samples of feces were collected from 257 asymptomatic patients and 20 cases of confirmed CRC, and they were tested simultaneously by the guaiac-based occult blood test and monoclonal antibody-based immunoassay kit. Colonoscopy was performed on all participants and the results were statistically analyzed with both positive and negative occult blood tests of both methods.

Results

Of the 277 subjects, 79 tested positive for occult blood with at least one method. Overall, the number of those with an occult blood-positive result by both tests was 39 (14.1%), while for 198 (71.5%), both tests were negative (P<0.0001); 40 (14.4%) samples showed a discrepant result. Colonoscopy data were obtained for all 277 patients. A total of three invasive cancers were detected among the screening group. Of the three, the guaiac test detected two cases, while the immunochemical test detected three of them. Of the 20 control cases, the guaiac test detected 13 CRC cases (P=0.03), while the immunochemical test detected 16 of them (P<0.0001). The sensitivity of guaiac and immunochemical tests for the detection of CRC in the screening group was 50.00% (95% confidence interval [CI] =6.76–93.24) and 75.00% (95% CI =19.41–99.37), respectively. For comparison, the sensitivity of the guaiac fecal occult blood test for detecting CRC among the control group was 65.00% (95% CI =40.78–84.61) while that of FIT was 80.00% (95% CI =56.34–94.27). The specificity of the guaiac and immunoassay tests was 77.87% (95% CI =72.24–82.83) and 90.12% (95% CI =85.76–93.50), respectively. The positive likelihood ratio of guaiac and immunochemical tests for the detection of CRC was 2.26 (95% CI =0.83–6.18) and 7.59 (95% CI =3.86–14.94), whereas the negative likelihood ratio was 0.64 (95% CI =0.24–1.71) and 0.28 (95% CI =0.05–1.52), respectively. The positive predictive values of guaiac and immunochemical tests were 3.45% (95% CI =0.426–11.91) and 10.71% (95% CI =2.27–28.23), respectively. There was no marked difference in the negative predictive values for both methods. The sensitivity of the fecal occult blood test by FIT was significantly higher for stages III and IV colorectal cancer than for stages I and II (P=0.01) and it was insignificant for the guaiac fecal occult blood test (P=0.07).

Conclusion

In areas where other advance screening methods of CRC are not feasible, the use of FIT can be considered.

Optimising colorectal cancer screening acceptance: a review

The study aims to review available evidence concerning effective interventions to increase colorectal cancer (CRC) screening acceptance. We performed a literature search of randomised trials designed to increase individuals' use of CRC screening on PubMed, Embase, Cochrane Database of Systematic Reviews and Database of Abstracts of Reviews of Effects. Small (≤ 100 subjects per arm) studies and those reporting results of interventions implemented before publication of the large faecal occult blood test trials were excluded. Interventions were categorised following the Continuum of Cancer Care and the PRECEDE-PROCEED models and studies were grouped by screening model (opportunistic vs organised). Multifactor interventions targeting multiple levels of care and considering factors outside the individual clinician control, represent the most effective strategy to enhance CRC screening acceptance. Removing financial barriers, implementing methods allowing a systematic contact of the whole target population, using personal invitation letters, preferably signed by the reference care provider, and reminders mailed to all non-attendees are highly effective in enhancing CRC screening acceptance. Physician reminders may support the diffusion of screening, but they can be effective only for individuals who have access to and make use of healthcare services. Educational interventions for patients and providers are effective, but the implementation of organisational measures may be necessary to favour their impact. Available evidence indicates that organised programmes allow to achieve an extensive coverage and to enhance equity of access, while maximising the health impact of screening. They provide at the same time an infrastructure allowing to achieve a more favourable cost-effectiveness profile of potentially effective strategies, which would not be sustainable in opportunistic settings.

Gastrointestinal cancer screening: screening may release new research funding to improve health service also in routine clinics

We are far from having seen the ideal method of screening for colorectal cancer (CRC) and the downsides of screening have not been fully addressed. Funding of adequately sized screening trials with a 10-15-year perspective for endpoints CRC mortality and incidence is difficult to get. Also, with such time horizons, there will always be an ongoing study to be awaited before feeling obliged to invest in the next. New, promising screening methods may, however, emerge far more often than every 10th year, and the knowledge gap may easily widen unless research is made a key responsibility for any ongoing cancer screening program. Previous lost battles on screening research may be won if accepting that scientific evidence may be obtained within the framework of screening programs - provided that they are designed as platforms for Comparative Effectiveness Research (CER). Accepting that CER-based screening programs should be preferred to non-CER programs and seriously compete for their funding sources, then CER screening programs may not be considered so much as contenders for ordinary clinical research funds. Also, CER within a screening framework may benefit patients in routine clinics as shown by screening research in Nordic countries. The Nordic countries have been early contributors to research on CRC screening, but slow in implementing screening programs.

Screening and Primary prevention of Colorectal Cancer: a Review of sex-specific and site-specific differences

Background

Colorectal cancer (CRC) is the second commonest cancer in England. Incidence rates for colorectal adenomas and advanced colorectal neoplasia are higher in men than in women of all age groups. The male-to-female ratio for CRC incidence rates differs for different parts of the large bowel.

Objective

To summarize the current evidence on colorectal screening and prevention, focussing on potential differences in benefits between sexes and colorectal sites.

Methods

(i), We reviewed the evidence from randomized controlled trials (RCTs) of the impact of different screening approaches on CRC incidence and mortality, overall, for each sex separately, and for subsites of the large bowel. (ii) We reviewed studies comparing detection parameters for faecal immunochemical tests for haemoglobin (FIT) with guaiac FOBt (gFOBt). (iii) The role of aspirin in CRC prevention in the general population was reviewed using evidence from RCTs, with specific emphasis on the differences observed between sexes and lesion site.

Results

(i) Our intention-to-treat random-effects meta-analysis showed that once-only flexible sigmoidoscopy (FS) screening performed on average-risk individuals aged 55 + decreased CRC incidence by 18% and mortality by 28%, but sex-specific results were lacking. (ii) Modern quantitative FIT were superior to qualitative gFOBt in average-risk population screening in their ability to discriminate between individuals with and without colorectal neoplasia. Some recent FIT studies suggest varying operating characteristics in men and women. (iii) Evidence of an effect of aspirin on the incidence of CRC (in particular, proximal disease) in both sexes aged 40 and over at average-risk of CRC is emerging.

Conclusions

We encourage researchers of CRC screening and prevention to publish their results by sex where possible. Pilot studies should be undertaken before implementation of quantitative FIT in a national screening programme to establish the appropriate threshold. Finally, individual risk assessment for CRC and non-CRC events, will be necessary to make an informed decision on whether a patient should receive aspirin chemoprevention.

Flexible sigmoidoscopy versus faecal occult blood testing for colorectal cancer screening in asymptomatic individuals

BACKGROUND

Colorectal cancer is the third most frequent cancer in the world. As the sojourn time for this cancer is several years and a good prognosis is associated with early stage diagnosis, screening has been implemented in a number of countries. Both screening with faecal occult blood test and flexible sigmoidoscopy have been shown to reduce mortality from colorectal cancer in randomised controlled trials. The comparative effectiveness of these tests on colorectal cancer mortality has, however, never been evaluated, and controversies exist over which test to choose.

OBJECTIVES

To compare the effectiveness of screening for colorectal cancer with flexible sigmoidoscopy to faecal occult blood testing.

SEARCH METHODS

We searched MEDLINE and EMBASE (November 16, 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 11) and reference lists for eligible studies.

SELECTION CRITERIA

Randomised controlled trials comparing screening with flexible sigmoidoscopy or faecal occult blood testing to each other or to no screening. Only studies reporting mortality from colorectal cancer were included. Faecal occult blood testing had to be repeated (annually or biennially).

DATA COLLECTION AND ANALYSIS

Data retrieval and assessment of risk of bias were performed independently by two review authors. Standard meta-analyses using a random-effects model were conducted for flexible sigmoidoscopy and faecal occult blood testing (FOBT) separately and we calculated relative risks with 95% confidence intervals (CI). We used a Bayesian approach (a contrast-based network meta-analysis method) for indirect analyses and presented the results as posterior median relative risk with 95% credibility intervals. We assessed the quality of evidence using GRADE.

MAIN RESULTS

We identified nine studies comprising 338,467 individuals randomised to screening and 405,919 individuals to the control groups. Five studies compared flexible sigmoidoscopy to no screening and four studies compared repetitive guaiac-based FOBT (annually and biennially) to no screening. We did not consider that study risk of bias reduced our confidence in our results. We did not identify any studies comparing the two screening methods directly. When compared with no screening, colorectal cancer mortality was lower with flexible sigmoidoscopy (relative risk 0.72; 95% CI 0.65 to 0.79, high quality evidence) and FOBT (relative risk 0.86; 95% CI 0.80 to 0.92, high quality evidence). In the analyses based on indirect comparison of the two screening methods, the relative risk of dying from colorectal cancer was 0.85 (95% credibility interval 0.72 to 1.01, low quality evidence) for flexible sigmoidoscopy screening compared to FOBT. No complications occurred after the FOBT test itself, but 0.03% of participants suffered a major complication after follow-up. Among more than 60,000 flexible sigmoidoscopy screening procedures and almost 6000 work-up colonoscopies, a major complication was recorded in 0.08% of participants. Adverse event data should be interpreted with caution as the reporting of adverse effects was incomplete.

AUTHORS' CONCLUSIONS

There is high quality evidence that both flexible sigmoidoscopy and faecal occult blood testing reduce colorectal cancer mortality when applied as screening tools. There is low quality indirect evidence that screening with either approach reduces colorectal cancer deaths more than the other. Major complications associated with screening require validation from studies with more complete reporting of harms

Current status of screening for colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer morbidity and mortality. A well-defined precursor lesion (adenoma) and a long preclinical course make CRC a candidate for screening. This paper reviews the current evidence for the most important tests that are widely used or under development for population-based screening.

MATERIAL AND METHODS

In this narrative review, we scrutinized all papers we have been aware of, and carried out searches in PubMed and Cochrane library for relevant literature.

RESULTS

Two screening methods have been shown to reduce CRC mortality in randomised trials: repetitive faecal occult blood testing (FOBT) reduces CRC mortality by 16%; once-only flexible sigmoidoscopy (FS) by 28%. FS screening also reduces CRC incidence (by 18%), FOBT does not. Colonoscopy screening has a potentially larger effect on CRC incidence and mortality, but randomised trials are lacking. New screening methods are on the horizon but need to be tested in large clinical trials before implementation in population screening.

CONCLUSIONS

FS screening reduces CRC incidence and CRC mortality by removal of adenomas; FOBT reduces CRC mortality by early detection of cancer. Several other tests are available, but none has been evaluated in randomised trials. Screening strategies differ considerably across countries.

Using resource modelling to inform decision making and service planning: the case of colorectal cancer screening in Ireland

Background

Organised colorectal cancer screening is likely to be cost-effective, but cost-effectiveness results alone may not help policy makers to make decisions about programme feasibility or service providers to plan programme delivery. For these purposes, estimates of the impact on the health services of actually introducing screening in the target population would be helpful. However, these types of analyses are rarely reported. As an illustration of such an approach, we estimated annual health service resource requirements and health outcomes over the first decade of a population-based colorectal cancer screening programme in Ireland.

Methods

A Markov state-transition model of colorectal neoplasia natural history was used. Three core screening scenarios were considered: (a) flexible sigmoidoscopy (FSIG) once at age 60, (b) biennial guaiac-based faecal occult blood tests (gFOBT) at 55–74 years, and (c) biennial faecal immunochemical tests (FIT) at 55–74 years. Three alternative FIT roll-out scenarios were also investigated relating to age-restricted screening (55–64 years) and staggered age-based roll-out across the 55–74 age group. Parameter estimates were derived from literature review, existing screening programmes, and expert opinion. Results were expressed in relation to the 2008 population (4.4 million people, of whom 700,800 were aged 55–74).

Results

FIT-based screening would deliver the greatest health benefits, averting 164 colorectal cancer cases and 272 deaths in year 10 of the programme. Capacity would be required for 11,095-14,820 diagnostic and surveillance colonoscopies annually, compared to 381–1,053 with FSIG-based, and 967–1,300 with gFOBT-based, screening. With FIT, in year 10, these colonoscopies would result in 62 hospital admissions for abdominal bleeding, 27 bowel perforations and one death. Resource requirements for pathology, diagnostic radiology, radiotherapy and colorectal resection were highest for FIT. Estimates depended on screening uptake. Alternative FIT roll-out scenarios had lower resource requirements.

Conclusions

While FIT-based screening would quite quickly generate attractive health outcomes, it has heavy resource requirements. These could impact on the feasibility of a programme based on this screening modality. Staggered age-based roll-out would allow time to increase endoscopy capacity to meet programme requirements. Resource modelling of this type complements conventional cost-effectiveness analyses and can help inform policy making and service planning.

Systematic review and meta-analysis of the evidence for flexible sigmoidoscopy as a screening method for the prevention of colorectal cancer

BACKGROUND

Colorectal cancer is a significant cause of death. Removal of precancerous adenomas, and early detection and treatment of cancer, has been shown to reduce the risk of death. The aim of this review and meta-analysis was to determine whether flexible sigmoidoscopy (FS) is an effective population screening method for reducing mortality from colorectal cancer.

METHODS

MEDLINE (1946 to December 2012) and Embase (1980-2012, week 15) were searched for randomized clinical trials in which FS was used to screen non-symptomatic adults from a general population, and FS was compared with either no screening or any other alternative screening methods. Meta-analysis was carried out using a random-effects Mantel-Haenzsel model.

RESULTS

Twenty-four papers met the inclusion criteria, reporting results from 14 trials. Uptake of FS was usually lower than that for stool-based tests, although FS was more effective at detecting advanced adenoma and carcinoma. FS reduced the incidence of colorectal cancer after screening, and long-term mortality from colorectal cancer, compared with no screening in a selected population. Compared with stool-based tests in a general population, FS was associated with fewer interval cancers.

CONCLUSION

FS is efficacious at reducing colorectal cancer mortality compared with no screening. It is more effective at detecting advanced adenoma and carcinoma than stool-based tests. FS may be compromised by poorer uptake. Introduction of FS as a screening method should be done on a pilot basis in populations in which it is not currently used, and close attention should be paid to maximizing uptake. The relative risk of adverse events with FS compared with stool-based tests should be quantified, and its real-world effectiveness evaluated against the most effective stool-based tests.

Cost-effectiveness of population-based screening for colorectal cancer: a comparison of guaiac-based faecal occult blood testing, faecal immunochemical testing and flexible sigmoidoscopy

BACKGROUND

Several colorectal cancer-screening tests are available, but it is uncertain which provides the best balance of risks and benefits within a screening programme. We evaluated cost-effectiveness of a population-based screening programme in Ireland based on (i) biennial guaiac-based faecal occult blood testing (gFOBT) at ages 55-74, with reflex faecal immunochemical testing (FIT); (ii) biennial FIT at ages 55-74; and (iii) once-only flexible sigmoidoscopy (FSIG) at age 60.

METHODS

A state-transition model was used to estimate costs and outcomes for each screening scenario vs no screening. A third party payer perspective was adopted. Probabilistic sensitivity analyses were undertaken.

RESULTS

All scenarios would be considered highly cost-effective compared with no screening. The lowest incremental cost-effectiveness ratio (ICER vs no screening euro 589 per quality-adjusted life-year (QALY) gained) was found for FSIG, followed by FIT euro 1696) and gFOBT (euro 4428); gFOBT was dominated. Compared with FSIG, FIT was associated with greater gains in QALYs and reductions in lifetime cancer incidence and mortality, but was more costly, required considerably more colonoscopies and resulted in more complications. Results were robust to variations in parameter estimates.

CONCLUSION

Population-based screening based on FIT is expected to result in greater health gains than a policy of gFOBT (with reflex FIT) or once-only FSIG, but would require significantly more colonoscopy resources and result in more individuals experiencing adverse effects. Weighing these advantages and disadvantages presents a considerable challenge to policy makers.

How to enhance physician and public acceptance and utilisation of colon cancer screening recommendations

Colorectal Cancer (CRC) screening delivery is a multidisciplinary undertaking, aiming at reducing mortality from and incidence of CRC without adversely affecting the health status of participants. The adoption of a public health perspective involves commitment to ensure equity of access and sustainability of the program over time. We reviewed available evidence concerning predictors of CRC screening uptake and the impact of interventions to improve adoption of screening using conceptual frameworks defining the role of determinants of preventive behaviours and the reach and target of interventions. The results of this review indicate that policy measures aimed at supporting screening delivery, as well as organisational changes, influencing the operational features of preventive services, need to be implemented, in order to allow individual's motivation to be eventually realised. To ensure coverage and equity of access and to maximise the impact of the intervention, policies aimed at implementing organised programs should be adopted, ensuring that participation in screening and any follow-up assessment should not be limited by financial barriers. Participants and providers beliefs may determine the response to different screening modalities. To achieve the desired health impact, an active follow-up of people with screening abnormalities should be implemented, supported by the introduction of infrastructural changes and multidisciplinary team work, which can ensure sustainability over time of effective interventions. Continuous monitoring as well as the adoption of plans to evaluate for program effectiveness represent crucial steps in the implementation of a successful program.

Screening for colorectal cancer

Colorectal cancer (CRC) is the most common cancer in the Nordic countries after breast and prostate cancer. About 15,000 new cancers are diagnosed and more than 7000 patients will die from CRC in 2005. CRC fulfils most of the criteria for applying screening; the natural history is well known compared with many other cancers. CRC may be cured by detection at an early stage and even prevented by removal of possible precursors like adenomas. Faecal occult blood test is the only CRC screening modality that has been subjected to adequately sized randomised controlled trials (RCT) with long-term follow-up results, using Hemoccult-II. Sensitivity for strictly asymptomatic CRC is less than 30% for a single screening round, but programme sensitivity has been estimated to be more. Biennial screening with un-rehydrated Hemoccult-II slides has shown a CRC mortality reduction of 15-18% after approximately 10 years of follow-up in those targeted for screening. For those attending, the mortality reduction has been estimated at 23%. Denmark has decided to do feasibility studies to try to evaluate whether a population-based screening run by the community will have the same effect as has been demonstrated in the randomised trials. In Norway the government has accepted no formal population-based screening. In Finland, the Ministry of Social Affairs and Health made a recommendation in 2003 to the municipalities to run a randomised feasibility study with FOBT screening for colorectal cancer as a public health policy that is repeated every second year. In 2004 the first municipalities started. It has been claimed that today Sweden cannot afford CRC screening despite the potential mortality benefit. There is sufficient evidence for the efficacy of screening for colorectal cancer with fecal occult blood test every second year. There is, however, only little evidence on the effectiveness of screening when run as a public health service and there is insufficient knowledge of harmful effects and costs, even in RCTs.

Screening for Rectal Cancer – Will it Improve Cure Rates?

Here we give an overview of colorectal cancer screening strategies with an emphasis on the diagnosis and management of rectal cancer. We review the published studies on screening in the high-risk population, including patients with a history of colorectal cancer, inflammatory bowel disease and inherited conditions. In the average-risk population, the evidence base for a number of screening strategies is evaluated, including endoscopy, contrast studies and faecal occult blood testing. Screening guidelines in the high-risk population are predominantly based on case-control studies comparing the incidence of colorectal cancer in screened and control groups. Screening the average-risk population for colorectal cancer reduces cancer-specific mortality by 15% after biennial guaiac faecal occult blood testing and 50-80% after flexible sigmoidoscopy. All of the screening strategies outlined have a greater sensitivity for distal lesions than proximal lesions.

Is the type of test used for mass colorectal cancer screening a determinant of compliance? A cluster-randomized controlled trial comparing fecal occult blood testing with flexible sigmoidoscopy

BACKGROUND

The efficacy of colorectal cancer screening has been proved, and three different screening tests are recommended by international guidelines: the faecal occult blood test, flexible sigmoidoscopy and colonoscopy. While the effectiveness of a screening program depends on the compliance obtained, the role of the type of test on compliance has not yet been sufficiently studied.

AIMS

To measure the effect of the type of screening test used, i.e. faecal occult blood test or flexible sigmoidoscopy, on the compliance to colorectal cancer screening programs.

SUBJECTS AND METHODS

A cluster-randomized two-arm trial was conducted. We randomly assigned 20 GP's practices that had an average of 150 patients between 50 and 74 years old.

RESULTS

1449 individuals were referred to faecal occult blood test and 1538 to flexible sigmoidoscopy. The faecal occult blood test obtained higher compliance: 17.2% (95%CI 12.5-25.7) versus 7.0% (95%CI 5.7-9.0). The socio-economic status was an effect modifier of the test type: the effect of the type of test was smaller in low socioeconomic classes.

CONCLUSIONS

The type of screening test used for colorectal cancer is a determinant of participation. In a low compliance area, better compliance will result from offering the faecal occult blood test than from the flexible sigmoidoscopy.

Colorectal cancer screening: health impact and cost effectiveness

BACKGROUND

Colorectal cancer is the second leading cause of cancer-related death in the United States, yet recommended screenings are not delivered to most people. This assessment of colorectal cancer screening's value to the U.S. population is part of the update to a 2001 ranking of recommended clinical preventive services found in the accompanying article. This article describes the burden of disease prevented and cost-effectiveness as a result of offering patients a choice of colorectal cancer screening tools.

METHODS

Methods used were designed to ensure consistent estimates across many services and are described in more detail in the companion articles. In a secondary analysis, the authors also estimated the impact of increasing offers for colorectal cancer screening above current levels among the current cross-section of adults aged 50 and older.

RESULTS

If a birth cohort of 4 million were offered screening at recommended intervals, 31,500 deaths would be prevented and 338,000 years of life would be gained over the lifetime of the birth cohort. In the current cross-section of people aged 50 and older, 18,800 deaths could be prevented each year by offering all people in this group screening at recommended intervals. Only 58% of these deaths are currently being prevented. In year 2000 dollars, the cost effectiveness of offering patients aged 50 and older a choice of colorectal cancer screening options is $11,900 per year of life gained.

CONCLUSIONS

Colorectal cancer screening is a high-impact, cost-effective service used by less than half of persons aged 50 and older.

Flexible sigmoidoscopy in the PLCO cancer screening trial: results from the baseline screening examination of a randomized trial

BACKGROUND

The Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial is a randomized clinical trial to test the effectiveness of cancer screening, including the effect of flexible sigmoidoscopy screening on colorectal cancer mortality. Here we report findings from the baseline screening flexible sigmoidoscopy examination.

METHODS

Analyses included 77,465 men and women aged 55-74 years who were enrolled at 10 screening centers. The trial administered baseline risk factor questionnaires, offered 60-cm flexible sigmoidoscopy examinations, referred patients with screen-detected colorectal polyps or masses to personal physicians, and tracked subjects with polyps or masses to determine results from diagnostic follow-up. Cochran-Mantel-Haenszel statistics and logistic regression were used to test for differences in proportions according to sex and age.

RESULTS

A total of 64 658 subjects (83.5%) underwent screening flexible sigmoidoscopy, and at least one polyp or mass was identified in 15,150 subjects (23.4%). Of these, 74.2% received follow-up lower endoscopic procedures. Follow-up lower endoscopy was more frequent in subjects with at least one larger (> or = 0.5 cm) polyp or mass (86.0% [95% confidence interval {CI} = 84.6% to 87.4%] and 81.0% [95% CI = 79.8% to 82.2%] in women and men, respectively) than in those with a smaller (< 0.5 cm) polyp or mass (69.1% [95% CI = 67.5% to 70.6%] and 65.4% [95% CI = 64.1% to 66.7%] in women and men, respectively). The yields per 1000 screened, depending on 5-year age group, were as follows: for colorectal cancer, 1.1-2.5 in women and 2.4-5.6 in men; for advanced adenoma, 18.0-30.4 in women and 36.1-49.1 in men; and for colorectal cancer or any adenoma, 50.6-79.6 in women and 101.9-128.6 in men. Approximately 77% (130/169) of the colorectal adenocarcinoma patients were stage I or II at diagnosis.

CONCLUSIONS

Acceptance of screening flexible sigmoidoscopy was high. Diagnostic follow-up varied according to polyp size, yet cancer or adenoma detection rates met expectations.

Randomized Trial of Different Screening Strategies for Colorectal Cancer: Patient Response and Detection Rates

BACKGROUND

Although there is general consensus concerning the efficacy of colorectal cancer screening, there is a lack of agreement about which routine screening strategy should be adopted. We compared the participation and detection rates achievable through different strategies of colorectal cancer screening.

METHODS

From November 1999 through June 2001 we conducted a multicenter, randomized trial in Italy among a sample of 55-64 year olds in the general population who had an average risk of colorectal cancer. People with previous colorectal cancer, adenomas, inflammatory bowel disease, a recent (< or =2 years) colorectal endoscopy or fecal occult blood test (FOBT), or two first-degree relatives with colorectal cancer were excluded. Eligible subjects were randomly assigned, within the roster of their general practitioner, to 1) biennial FOBT (delivered by mail), 2) biennial FOBT (delivered by general practitioner or a screening facility), 3) patient's choice of FOBT or "once-only" sigmoidoscopy, 4) "once-only" sigmoidoscopy, or 5) sigmoidoscopy followed by biennial FOBT. An immunologic FOBT was used. Participation and detection rates of the strategies tested were compared using multivariable logistic regression models that adjusted for age, sex, and screening center. All statistical tests were two-sided.

RESULTS

Of 28 319 people sampled, 1637 were excluded and 26 682 were randomly assigned to a screening arm. After excluding undelivered letters (n = 427), the participation rates for groups 1, 2, 3, 4, and 5 were 30.1% (682/2266), 28.1% (1654/5893), 27.1% (970/3579), 28.1% (1026/3650), and 28.1% (3049/10 867), respectively. Of the 2858 subjects screened by FOBT, 122 (4.3%) had a positive test result, 10 (3.5 per 1000) had colorectal cancer, and 39 (1.4%) had an advanced adenoma. Among the 4466 subjects screened by sigmoidoscopy, 341 (7.6%) were referred for colonoscopy, 18 (4 per 1000) had colorectal cancer, and 229 (5.1%) harbored an advanced adenoma.

CONCLUSIONS

The participation rates were similar for sigmoidoscopy and FOBT. The detection rate for advanced neoplasia was three times higher following screening by sigmoidoscopy than by FOBT.

Screening sigmoidoscopy in persons aged 60 years

OBJECTIVE: To reduce mortality associated with colorectal cancer, an increased interest has focused in recent years on screening of colorectal cancer. No studies of colorectal cancer screening in Finland has been reported. A pilot study of screening sigmoidoscopy was started in 1994 and the results are presented in this paper.SUBJECTS AND METHODS: Between March 1994 and May 2000 all 1224 persons aged 60 years from four communities (population 15 400) were invited to screening sigmoidoscopy; 896 (73%) took part in this study. The screening procedure was flexible sigmoidoscopy to 60 centimetres. All the patients who had adenomas or cancers, were invited to have a double contrast barium enema (DCBE) or colonoscopy to investigate the proximal colon. To study the experience of persons undergoing screening sigmoidoscopy, a questionnaire was sent to 81 consecutive persons after the examination. Sixty persons (74%) returned the filled-in questionnaire.RESULTS: Hyperplastic polyps were found in 136 people (15.2% of the whole material). Hyperplastic polyps were more common in males than females (19.3% and 11.4%, respectively, P=0.0015). People with hyperplastic polyps had the same rate of neoplasia as people without. Neoplastic lesions were found in 65 people. Adenomas were found in 62 patients (6.9%). Twenty-five people (2.8%) had at least one advanced adenoma (>10 mm or villous component). The rate of advanced adenomas in males was 4.9% and in females 0.9% (P=0.0006). Three patients (0.3%) were found to have colorectal cancer. Of 43 diabetic patients, 7 (16.3%) had adenomas whereas 6.5% of the non-diabetic persons had adenomas (P=0.03). The proximal colon was investigated in 34 patients by DCBE and/or colonoscopy and the rate of proximal adenomas in patients with neoplastic findings in screening sigmoidoscopy was 5/34 (14.7%). Concerning the experience of screening sigmoidoscopy, 56 persons (93%) found bowel preparation easy and 4 unpleasant, 55 (92%) experienced either no or mild discomfort during the endoscopy whereas 5 found the examination painful; 59 people (98%) said that they would participate again in screening sigmoidoscopy.CONCLUSIONS: In this study of screening sigmoidosopy, the first published in Finland, adenoma rate was 6.9%, advanced adenoma rate was 2.8% and cancer rate was 0.3%. Males had more hyperplastic polyps and advanced adenomas than females. Diabetic people had more adenomas than non-diabetics. Experiences of the people screened were positive and nearly all said that they would participate again in screening sigmoidoscopy.

Possible advantages and drawbacks of adding flexible sigmoidoscopy to hemoccult-II in screening for colorectal cancer. A randomized study

BACKGROUND

Flexible sigmoidoscopy (FS) has been recommended as a screening method to reduce mortality from colorectal cancer (CRC). The present study evaluates the effect of adding FS to the fecal occult blood test Hemoccult-II (H-II) on diagnostic yield of colorectal neoplasia.

METHODS

A total of 10,978 normal persons aged 50-75 years were invited to participate, 5495 persons being allocated at random to H-II and FS and 5483 to H-II alone.

RESULTS

In spite of a lower compliance (40% versus 56%) for the combined procedure, the diagnostic yield of colorectal neoplasia was higher than for H-II alone (12 CRC versus 4 CRC, and 72 large adenomas versus 14). Within 24-62 months after screening there were fewer CRCs detected after H-II + FS than after H-II alone. The stage distribution was less favorable than in screen-detected cases.

CONCLUSION

One FS may not be an optimal way of screening, but FS deserves to be evaluated in randomized population studies including repeated H-II tests in the control arm.