Colorectal cancer screening:20 years of development and recent progress

Colorectal cancer(CRC)is the second most common cancer in Europe and its incidence is steadily increasing.This trend could be reversed through timely secondary prevention(screening).In the last twenty years,CRC screening programs across Europe have experienced considerable improvements(fecal occult blood testing;transition from opportunistic to population based program settings).The Czech Republic is a typical example of a country with a long history of nationwide CRC screening programs in the face of very high CRC incidence and mortality rates.Each year,approximately 8000 people are diagnosed with CRC and some 4000 die from this malignancy.Twenty years ago,the first pilot studies on CRC screening led to the introduction of the opportunistic Czech National Colorectal Cancer Screening Program in 2000.Originally,this program was based on the guaiac fecal occult blood test(FOBT)offered by general practitioners,followed by colonoscopy in cases of FOBT positivity.The program has continuously evolved,namely with the implementation of immunochemical FOBTs and screening colonoscopy,as well as the involvement of gynecologists.Since the establishment of the Czech CRC Screening Registry in 2006,2405850 FOBTs have been performed and 104565 preventive colonoscopies recorded within the screening program.The overall program expanded to cover 25.0%of the target population by 2011.However,stagnation in the annual number of performed FOBTs lately has led to switching to the option of a population-based program with personal invitation,which is currently being prepared.     

Strategies in screening for colon carcinoma

Colorectal cancer is the second most common cancer in Europe and meets the criteria for population screening. Population screening should lead to a reduction in CRC-related mortality and incidence. Several options are available for CRC screening, which can be itemised as stool-based tests and structural exams. Stool-based tests include guaiac and immunochemical faecal occult blood tests and DNA -marker tests. Structural exams comprise endoscopic techniques (flexible sigmoidoscopy, colonoscopy and capsule endoscopy) and radiological exams (double contrast barium enema, CT colonography and MR colonography). Each test has its own test performance characteristics and acceptability profile, which affect the participation and effectiveness of the associated screening programmes. Faecal occult blood tests (FOBT ) and flexible sigmoidoscopy (FS) are the only methods with a demonstrated mortality reduction during a ten-year period (FOBT 16% and FS 31%) while flexible sigmoidoscopy is the only screening test with a demonstrated reduction in CRC incidence (23%). It is likely that other screening techniques such as colonoscopy and CT colonography will also be effective in the reduction of CRC-related mortality. DNA -marker tests, capsule endoscopy and MR colonography are possible options for the future.     

Options for screening for colorectal cancer

Unlike other types of cancer, there are several options for screening for colorectal cancer (CRC). The most extensively examined method, faecal occult blood testing (FOBT), has been shown, in three large randomized trials, to reduce mortality from CRC by up to 20% if offered biennally and possibly more if offered every year. Recently published data from the US trial suggest that CRC incidence rates are also reduced by up to 20%, but only after 18 years. In this study, the number of positive slides was associated with the positive predictive value both for CRC and adenomas larger than 1 cm, suggesting that the reduction in CRC incidence was caused by the identification and removal of large adenomas. In this respect, this study supports the concept that removing adenomas prevents CRC. More efficient methods of detecting adenomas include the use of colonoscopy or flexible sigmoidoscopy (FS). Considerable evidence exists from case-control and uncontrolled cohort studies to suggest that endoscopic screening by sigmoidoscopy reduces incidence of distal colorectal cancer. However, in the absence of evidence from a randomized trial, several countries have been reluctant to introduce endoscopic screening. Three trialsare currently in progress (in the UK, Italy and the US) to address this issue. Two of these trials are examining the hypothesis that a single FS screen at around age 55-64 might be a cost-effective and acceptable method for reducing CRC incidence rates. Recruitment and screening are now complete in both studies and the first analysis of results on incidence rates is expected in 2004. Colonoscopy screening at 10-year intervals has recently been endorsed in the US on the basis that the reductions in incidence observed with distal CRC screening can be extrapolated to the proximal colon. However, data are lacking and a pilot study for a trial of the acceptability and efficacy of colonoscopy screening is in progress in the US. It has also been suggested that FOBT testing should be used to detect proximal CRC missed by sigmoidoscopy screening, but the small amount of published data suggest that supplementing FS with FOBT offers very little advantage over FS alone. Other forms of CRC screening are under investigation and represent exciting options for the future. Extraction of DNA from stool is now feasible and a number of research groups have shown high sensitivity for CRC using a panel of DNA markers including mutations in k-ras, APC, p53 and BAT26. Data so far indicate that, with the exception of k-ras, these markers are highly specific and therefore represent a significant improvement over FOBT. Whether these tests will replace or supplement existing methods of screening has yet to be determined. It has been suggested that BAT26, which is a marker of microsatellite instability, a feature of proximal sporadic CRC, might be a useful adjunct to sigmoidoscopy screening. Others have suggested that a test for occult blood should be included with the DNA markers to further increase sensitivity. It is not yet known how sensitive these markers are for adenomas--it is only by detecting adenomas that CRC incidence rates can be reduced. A final exciting new option for screening is virtual colonoscopy (VC), which by screening out people without neoplasia allows colonoscopy to be reserved for patients requiring a therapeutic intervention. The sensitivity of VC for large adenomas and CRC appears to be high, although results vary by centre and there is a steep learning curve. Sensitivity for small adenomas is low, but perhaps it is less essential to find such lesions. Some groups have suggested that virtual colonoscopy might be a useful option for investigating patients who test positive with stool-based screening tests. Whichever CRC screening method is finally chosen (and there is no reason why several methods should not ultimately be available), high quality endoscopy resources will always be required to investigate and treat neoplastic lesions detected.     

Tumor pyruvate kinase isoenzyme type M2 and immunochemical fecal occult blood test: performance in screening for colorectal cancer

OBJECTIVES: Immunochemical fecal occult blood test (FOBT) and determination of tumor pyruvate kinase isoenzyme type M2 (TuM2-PK) in stool samples may be valuable new screening tools for colorectal cancer (CRC). The aim of this study was to compare the accuracy of fecal TuM2-PK testing with immunochemical FOBT in patients with CRC or adenomas. METHODS: A total of 52 patients with CRC were analyzed, 47 with colorectal adenomas, and 63 matched controls with a normal colonoscopy. Nineteen additional patients with inflammatory bowel disease were tested to determine influence of inflammation. Stool samples were analyzed with two immunochemical FOBTs, Immo-care and OC-Light, and with a commercial enzyme-linked immunosorbent assay for TuM2-PK. RESULTS: In patients with CRC, the sensitivity of TuM2-PK, Immo-care and OC-Light was respectively 85, 92 and 94%. In patients with adenomas, the sensitivity was respectively 28, 40 and 34%. Specificity for these tests was 90% for TuM2-PK and 97% for both immunochemical FOBTs. All tests showed a high positivity rate in patients with inflammatory bowel disease (79% for TuM2-PK and Immo-care, and 89% for OC-Light). CONCLUSION: Both immunochemical FOBTs appear valuable and are sensitive tests for CRC screening. TuM2-PK does not have supplemental value for screening for CRC because of a lower sensitivity and specificity. None of these tests is sensitive enough for detection of advanced adenomas. Patients with inflammatory bowel disease should be excluded from CRC screening when using immunochemical FOBT or TuM2-PK.     

Colon cancer prevention in Italy: Cost-effectiveness analysis with CT colonography and endoscopy

BACKGROUND: Colorectal cancer (CRC) is a major cause of mortality in Italy. Although prevention of CRC is possible, its cost-effectiveness when applied to the Italian population is unknown. Recently, computerized tomographic colonography (CTC) has been proposed for CRC screening. AIM: To compare the efficacy and cost-effectiveness of CTC screening in a simulated Italian population with those of colonoscopy and flexible sigmoidoscopy (FS). METHODS: The cost-effectiveness of different screening strategies was compared using a Markov process computer model, in which in a hypothetical population of 100,000 50 year-olds were investigated by CTC, colonoscopy or FS every decade. Outcomes were projected to the Italian national level. RESULTS: CRC incidence reduction was calculated at 40.9%, 38.2%, and 31.8% with colonoscopy, CTC and FS, respectively. As compared to no screening, all screening programs were shown to be cost-saving, allowing a saving of 11 Euro, 17 Euro, and 48 Euro per person with colonoscopy, FS and CTC, respectively. FS appeared to be less cost-effective than CTC, whilst colonoscopy appeared to be an expensive option as compared to CTC. Undiscounted national expenditure was calculated to be 1,042,489,512 Euro, 1,093,268,285 Euro, and 1,198,783,428 Euro for FS, CTC and colonoscopy, respectively, as compared to 695,818,078 Euro without screening. CONCLUSION: CRC screening is cost-saving in Italy, irrespective of the technique applied. CTC appeared to be more cost-effective than FS, and it may also become a valid alternative to colonoscopy.     

Fecal DNA testing compared with conventional colorectal cancer screening methods: a decision analysis

BACKGROUND & AIMS: Fecal DNA testing is an emerging tool to detect colorectal cancer (CRC). Our aims were to estimate the clinical and economic consequences of fecal DNA testing vs. conventional CRC screening. METHODS: Using a Markov model, we estimated CRC incidence, CRC mortality, and discounted cost/life-year gained for screening by fecal DNA testing (F-DNA), fecal occult blood testing (FOBT) and/or sigmoidoscopy, or colonoscopy (COLO) in persons at average CRC risk from age 50 to 80 years. RESULTS: Compared with no screening, F-DNA at a screening interval of 5 years decreased CRC incidence by 35% and CRC mortality by 54% and gained 4560 life-years per 100,000 persons at USD $47,700/life-year gained in the base case. However, F-DNA gained fewer life-years and was more costly than conventional screening. The average number of colonoscopies per person was 3.8 with COLO and 0.8 with F-DNA. In most 1-way sensitivity analyses and Monte Carlo simulation iterations, F-DNA remained reasonably cost-effective compared with no screening, but COLO and FOBT dominated F-DNA. Assuming fecal DNA testing sensitivities of 65% for CRC and 40% for large polyp, and 95% specificity, a screening interval of 2 years and a test cost of USD $195 would be required to make F-DNA comparable with COLO. CONCLUSIONS: Fecal DNA testing every 5 years appears effective and cost-effective compared with no screening, but inferior to other strategies such as FOBT and COLO. Fecal DNA testing could decrease the national CRC burden if it could improve adherence with screening, particularly where the capacity to perform screening colonoscopy is limited.     

结直肠癌筛查及其进展

结直肠癌(CRC)是最常见的恶性肿瘤之一,近年来我国CRC发病率总体呈现上升趋势,在消化系统恶性肿瘤中居第二位。CRC筛查可显著降低其发病率和死亡率,筛查方法多样,目前以免疫化学法粪便隐血试验(FIT)和结肠镜检查为基础的两步法筛查方案为多个国家的权威指南或共识所推荐,其他筛查方法可作为个体化的选择和补充。对于结直肠息肉超过10枚同时有CRC个人史或家族史,或结直肠息肉超过20枚的极高危人群,应行多基因种系突变检测。     

Reduction in colorectal cancer mortality by fecal occult blood screening in a French controlled study

BACKGROUND & AIMS: Several randomized population-based studies have shown that screening for colorectal cancer (CRC) by fecal occult blood tests (FOBTs) can reduce CRC mortality. The aim of this French population-based study was to assess whether a similar benefit could be obtained in countries characterized by high performances in the diagnosis and management of CRC. METHODS: Small-sized geographic areas, including 91,199 individuals aged 45-74 years, were allocated to either FOBT screening or no screening. Six screening rounds were performed. The FOBT was performed without diet restriction and was sent to a central analysis center and processed without rehydration. Screening group participants who had a positive test result were offered a full colonoscopy. The entire population was followed up for 11 years after study entry. RESULTS: Acceptability of the test was 52.8% at the first screening round and varied between 53.8% and 58.3% in the successive rounds. Positivity rates were 2.1% initially and 1.4% on average in the successive rounds. CRC mortality was significantly lower in the screening population compared with the control population (mortality ratio, 0.84; 95% confidence interval, 0.71-0.99). The reduction in CRC mortality was more pronounced in those who participated at least once (mortality ratio, 0.67; 95% confidence interval, 0.56-0.81). CONCLUSIONS: Our findings, together with the results of other trials, suggest that biennial screening by FOBTs can reduce CRC mortality regardless of the quality of the health system and support attempts to introduce large-scale screening programs into the general population.     

Advances in colorectal cancer screening

Colorectal cancer (CRC) remains the third most commonly diagnosed cancer and second leading cause of cancer death in the United States. Declines in CRC incidence and mortality over the past 20 years were attributed to CRC screening. Yet, only slightly more than half of the eligible at-risk population acknowledge being screened. To effectively meet the demands of screening in an enlarging, ethnically diverse, and aging population, a variety of modalities are needed. This article provides a focused assessment of effectiveness, limitations, and alternative available screening methods. New modalities endorsed in the updated guidelines (eg, fecal immunochemical tests, fecal DNA, and CT colonography) are reviewed. In addition, advances and updates in existing tests (eg, guaiac-based fecal occult blood tests and colonoscopy) are evaluated.     

New era of colorectal cancer screening

Colorectal cancer（CRC） is the 2^nd most common cancer in women and 3^rd most common cancer in men worldwide. Most CRCs develop from adenomatous polyps arising from glandular epithelium. Tumor growth is initiated by mutation of the tumor suppressor gene APC and involves other genetic mutations in a stepwise process over years. Both hereditary and environmental factors contribute to the development of CRC. Screening has been proven to reduce the incidence of CRC. Screening has also contributed to the decrease in CRC mortality in the United States. However,CRC incidence and/or mortality remain on the rise in some parts of the world（Eastern Europe,Asia,and South America）,likely due to factors including westernized diet,lifestyle,and lack of healthcare infrastructure. Multiple screening options are available,ranging from direct radiologic or endoscopic visualization tests that primarily detect premalignant or malignant lesions such as flexible sigmoidoscopy,optical colonoscopy,colon capsule endoscopy,computed tomographic colonography,and double contrast barium enema- to stool based tests which primarily detect cancers,including fecal DNA,fecal immunochemical test,and fecal occult blood test. The availability of some of these tests is limited to areas with high economic resources. This article will discuss CRC epidemiology,pathogenesis,risk factors,and screening modalities with a particular focus on new technologies.     

A population-based estimate of the extent of colorectal cancer screening in Ontario

BACKGROUND/OBJECTIVE: The incidence and mortality rates for colorectal cancer (CRC) in Canada are among the highest in the world. For individuals >/=50 yr, CRC screening is effective in reducing both CRC incidence and mortality. The goal of this research was to conduct a Canadian population-based study of the use of tests and procedures to evaluate the large bowel to estimate the extent of CRC screening. METHODS: We identified an inception cohort of all residents of Ontario aged 50-59 on January 1, 1995, without a previous history of CRC or large-bowel evaluation by five tests or procedures: fecal occult blood test (FOBT), barium enema, rigid sigmoidoscopy, flexible sigmoidoscopy, and colonoscopy. We followed these individuals to December 31, 2000, identified all tests received, and determined the proportion that received one or more tests or procedures of each type. Data were obtained from three sources: the Ontario Health Insurance Plan (OHIP) database, the Canadian Institute for Health Information-Discharge Abstract Database (CIHI-DAD), and the Registered Persons Database (RPDB). RESULTS: We identified 982,443 individuals in our inception cohort without prior CRC or large bowel evaluation. The proportion that had at least one test or procedure was less than 10% for each type. The largest proportion (9.3%) had one or more FOBTs. Classified according to the initial test received, 14.5% had a non-endoscopic test (FOBT, barium enema) and 6% had an endoscopic test (rigid sigmoidoscopy, flexible sigmoidoscopy, colonoscopy). The majority (79.5%) had no test or procedure to evaluate the large bowel. CONCLUSION: An extraordinarily low proportion (<20.5%) of screen-eligible 50-59-yr-old men and women in Ontario were screened for CRC during a 6-yr follow-up. Given the high burden of CRC in Canada a major opportunity exists to improve the health of Canadians by increasing our screening efforts.     

Case-control study of screening colonoscopy in relatives of patients with colorectal cancer

OBJECTIVES: The efficacy of colonoscopic screening and polypectomy for the prevention of colorectal cancer (CRC) is well accepted but has never been documented in a prospective, controlled study. Screening by sigmoidoscopy has been found to reduce mortality from cancer of the rectum and distal colon. Case-control studies provide an alternative method for determining the efficacy of screening methods. METHODS: Between 1998 and 2000, a total of 40 subjects were found to have CRC (study group) and 160 had a normal colon (control group) among asymptomatic individuals participating in a screening colonoscopy program for a high-risk population of first-degree relatives of CRC patients. We compared these groups for screening by fecal occult blood testing, flexible sigmoidoscopy, barium enema, and colonoscopy in the 10-yr period before the index colonoscopy. RESULTS: Screening colonoscopy was performed in only 2.5% of the case subjects and 48.7% of controls (p < 0.0001), and all screening procedures in 12.5% and 73.7%, respectively (p < 0.0001). A statistically significant difference was also found for screening with fecal occult blood test, but not for flexible sigmoidoscopy or barium enema. Significant adenomatous polyps >1 cm in diameter were detected and removed in 19% of the control group within 10 yr of the index colonoscopy. Six (15%) of the patients in the study group died of CRC. CONCLUSIONS: Screening by colonoscopy can prevent progression to CRC from adenomatous polyps and may reduce the mortality associated with this devastating disease.     

Current and future molecular diagnostics in colorectal cancer and colorectal adenoma

Colorectal cancer(CRC)is one of the most prevalent cancers in developed countries.On the other hand,CRC is also one of the most curable cancers if it is detected in early stages through regular colonoscopy or sigmoidoscopy.Since CRC develops slowly from precancerous lesions,early detection can reduce both the incidence and mortality of the disease.Fecal occult blood test is a widely used non-invasive screening tool for CRC.Although fecal occult blood test is simple and cost-effective in screening CRC,there is room for improvement in terms of the accuracy of the test.Genetic dysregulations have been found to play an important role in CRC development.With better understanding of the molecular basis of CRC,there is a growing expectation on the development of diagnostic tests based on more sensitive and specific molecular markers and those tests may provide a breakthrough to the limitations of current screening tests for CRC.In this review,the molecular basis of CRC development,the characteristics and applications of different non-invasive molecular biomarkers,as well as the technologies available for the detection were discussed.This review intended to provide a summary on the current and future molecular diagnostics in CRC and its pre-malignant state,colorectal adenoma.     

Choice of fecal occult blood tests for colorectal cancer screening: recommendations based on performance characteristics in population studies: a WHO (World Health Organization) and OMED (World Organization for Digestive Endoscopy) report

OBJECTIVE: There is now strong evidence that screening for colorectal cancer with fecal occult blood tests (FOBTs) is effective in reducing the incidence and mortality of this disease. Various FOBTs are now available with a wide range of evidence supporting their use. The purpose of this study was to review published data on the performance of these FOBTs to provide recommendations for their effective use in screening. METHODS: A joint committee representing the World Health Organization and the World Organization for Digestive Endoscopy was established for this study. A process was designed that would search the literature systematically for evidence of FOBT performance. Criteria for including studies in this paper were established based on study design, cohort size, and performance variables reported. RESULTS: Of the guaiac tests, Hemoccult SENSA had the highest sensitivity for cancer and adenomas but a high test positivity. It had a better readability than the older Hemoccult II test. Immunochemical tests, HemeSelect, FlexSure OBT, and Immudia Hem Sp have acceptable performance characteristics and are easier for participants to use but are more expensive. These tests have been well studied in large cohorts, but only Immudia Hem Sp is commercially available. CONCLUSIONS: At present, there is no extensively studied FOBT that fulfills the needs for all target populations worldwide. Choice of FOBT should take into account population dietary compliance and colonoscopy resources: The more sensitive newer tests should be used if dietary compliance is good (in the case of guaiac tests) and colonoscopy resources are adequate for diagnostic workup of people who test positive. Immunochemical tests remove the difficulties created by diet and drug restrictions and are more amenable to standardized development and quality control.     

Relationship between the number of positive fecal occult blood tests and the diagnostic yield of colonoscopy

BACKGROUND:

In 2007, Ontario launched a colon cancer screening program for average-risk individuals based on biennial fecal occult blood tests (FOBTs) on three fecal samples, followed by colonoscopy for individuals who tested positive.

OBJECTIVE:

To determine whether >1 positive screening FOBT was predictive of finding advanced neoplasia at colonoscopy.

METHODS:

A retrospective chart review of outpatient colonoscopic procedures performed at Hotel Dieu Hospital (Kingston, Ontario) in the first two years of the colon cancer screening program was conducted, focusing on endoscopic and pathological findings.

RESULTS:

Of 5556 individuals undergoing colonoscopy, 346 were referred for positive FOBT. Overall, 41 (11.8%) patients with a positive FOBT had colon cancer. In 16 (4.6%) cases, the number of positive FOBTs was not reported. For the 330 individuals in whom the number of positive tests was specified, 198, 71 and 61 cases had one, two and three positive results, respectively. Cancer was found at colonoscopy in 11 (5.6%), 11 (15.5%) and 18 (29.5%) of individuals with one, two and three positive FOBT results, respectively (OR 3.0 [95% CI 1.2 to 7.3] and 6.5 [95% CI 2.8 to 15.0] for two or three positive FOBTs compared with one; P=0.015 and P<0.001, respectively). High-risk adenomas (>1 cm in diameter, villous component and/or high-grade dysplasia) were found in 41 (20.8%), 29 (42.0%) and 25 (41.0%) individuals with one, two and three positive FOBTs, respectively (OR 2.8 [95% CI 1.5 to 5.0] and 2.4 [95% CI 1.3 to 4.5] for two or three positive FOBTs compared with one; P=0.001 and P=0.006, respectively).

CONCLUSIONS:

The diagnostic yield of colonoscopy varied directly with the number of positive FOBTs. This information may be useful in assigning scheduling priority for patients with positive FOBTs.     

Rates and Correlates of Potentially Inappropriate Colorectal Cancer Screening in the Veterans Health Administration

BACKGROUND

Inappropriate use of colorectal cancer (CRC) screening procedures can inflate healthcare costs and increase medical risk. Little is known about the prevalence or causes of inappropriate CRC screening.

OBJECTIVE

Our aim was to estimate the prevalence of potentially inappropriate CRC screening, and its association with patient and facility characteristics in the Veterans Health Administration (VHA) .

DESIGN AND PARTICIPANTS

We conducted a cross-sectional study of all VHA patients aged 50 years and older who completed a fecal occult blood test (FOBT) or a screening colonoscopy between 1 October 2009 and 31 December 2011 (n = 1,083,965).

MAIN MEASURES

Measures included: proportion of patients whose test was classified as potentially inappropriate; associations between potentially inappropriate screening and patient demographic and health characteristics, facility complexity, CRC screening rates, dependence on FOBT, and CRC clinical reminder attributes.

KEY RESULTS

Of 901,292 FOBT cases, 26.1 % were potentially inappropriate (13.9 % not due, 7.8 % limited life expectancy, 11.0 % receiving FOBT when colonoscopy was indicated). Of 134,335 screening colonoscopies, 14.2 % were potentially inappropriate (10.4 % not due, 4.4 % limited life expectancy). Each additional 10 years of patient age was associated with an increased likelihood of undergoing potentially inappropriate screening (ORs = 1.60 to 1.83 depending on screening mode). Compared to facilities scoring in the bottom third on a measure of reliance on FOBT (versus screening colonoscopy), facilities scoring in the top third were less likely to conduct potentially inappropriate FOBTs (OR = 0.,78) but more likely to conduct potentially inappropriate colonoscopies (OR = 2.20). Potentially inappropriate colonoscopies were less likely to be conducted at facilities where primary care providers were assigned partial responsibility (OR = 0.74) or full responsibility (OR = 0.73) for completing the CRC clinical reminder.

CONCLUSIONS

A substantial number of VHA CRC screening tests are potentially inappropriate. Establishing processes that enforce appropriate screening intervals, triage patients with limited life expectancies, and discourage the use of FOBTs when a colonoscopy is indicated may reduce inappropriate testing.KEY WORDS: colorectal cancer, screening, utilization, practice variation, VeteransIn 2014, an estimated 136,830 Americans will be diagnosed with colorectal cancer (CRC),¹ and an estimated 50,310 will die of the disease.¹ Appropriately applied, routine screening can reduce both CRC incidence and mortality.² Thus, many health organizations, including the Veterans Health Administration (VHA), have invested heavily in programs to increase CRC screening. Clinical reminder systems are now commonly used to alert providers at the point of care when patients are due for screening. CRC screening performance measures are now included in most quality measurement systems. In the VHA, CRC screening rates are used as one measure of the quality of care provided by physicians, clinics and facilities, and can affect clinician and administrator compensation plans. As a result, the VHA CRC screening rate of 80 %³ is well above US general population rates.⁴One potential unintended consequence of the emphasis on screening promotion is the inappropriate use of screening tests. There are at least three reasons a CRC screening test could be clinically inappropriate. First, the patient may not be due for screening. The US Preventive Services Task Force recommends screening with fecal occult blood tests (FOBTs) annually, with colonoscopy every 10 years, or with flexible sigmoidoscopy every 5 years.⁵ Second, the patient may be unlikely to live long enough to realize a screening benefit. Decision analyses and a meta-analysis of randomized controlled trial (RCT) data suggest that average-risk individuals with a life expectancy of less than 10 years are unlikely to benefit from CRC screening.^6,7 Third, the patient may receive the wrong test. Generally, patients with CRC-related symptoms or with a personal or family history of CRC should undergo colonoscopy (not FOBT or other tests).⁸ Screening patients who are not yet due or who are of limited life expectancy can strain gastroenterology and laboratory resources and expose patients to unnecessary inconvenience, stress, and medical risk. Serious complications are estimated to occur in 25 per 10,000 colonoscopy procedures,⁹ and deaths attributable to colonoscopy occur in three per 10,000 procedures.¹⁰ These forms of inappropriate screening can result in harm even when FOBTs are used because, if the FOBT is positive, the patient may undergo a diagnostic colonoscopy. Utilizing FOBTs when a colonoscopy is indicated may delay or decrease the likelihood of undergoing a needed colonoscopy, potentially decreasing the benefits of screening.Previous studies of inappropriate CRC screening^11–14 assessed only one facility, one screening mode, or one category of inappropriate screening. The current study quantifies the extent of potentially inappropriate screening for both FOBT and colonoscopy in the entire VHA system (130 medical facilities), using a measure that distinguishes between three types of inappropriate screening (not due, limited life expectancy, and wrong test), and examines the association between this measure and patient and facility attributes.     

Guidelines for colorectal cancer screening--a puzzle of tests and strategies

Colorectal cancer (CRC) is a leading cause of cancer death around the World. An effective way to reduce colorectal cancer mortality is to screen for it and its precursor, the adenoma. In industrialized countries the mortality related to CRC is decreasing probably due to better screening programmes in average-risk individuals as well as changes in risk factors. Screening procedures are various including faecal screening tests--which primarily detect colon cancer--and structural tests (endoscopy--flexible sigmoidoscopy or colonoscopy--, Barium enema, Computed Tomography Colonography) that may detect not only cancer but also its precursors. Video-colon capsule is a new tool for exploring the colon but needs further studies before becoming a screening test. The choice of a screening test includes several factors as cost, invasiveness, acceptability, adherence to repeat testing and acceptance referral for colonoscopy for positive tests as well as local financial resources. Every screening programme has advantages and limitations. Enhancing use and quality of CRC screening programmes is mandatory.     

Barriers to colorectal cancer screening： A case-control study

AIM： To investigate barriers to colorectal cancer （CRC） screening in a community population. METHODS： We conducted a community-based case-control study in an urban Chinese population by questionnaire. Cases were selected from those completing both a fecal occult blood test （FOBT） case and colonoscopy in a CRC screening program in 2004. Control groups were matched by gender, age group and community. Control 1 included those having a positive FOBT but refusing a colonoscopy. Control 2 included those who refused both an FOBT and colonoscopy. RESULTS： The impact of occupation on willingness to attend a colorectal screening program differed by gender. P for heterogeneity was 0.009 for case vs control group 1, 0.01 for case versus control group 2, and 0.80 for control group 1 vs 2. Poor awareness of CRC and its screening program, characteristics of screening tests, and lack of time affected thescreening rate. Financial support, fear of pain and bowel preparation were barriers to a colonoscopy as a screening test. Eighty-two percent of control group 1 and 87.1% of control group 2 were willing attend if the colonoscopy was free, but only 56.3% and 53.1%, respectively, if it was self-paid. Multivariate odds ratios for case vs control group 1 were 0.10 among those unwilling to attend a free colonoscopy and 0.50 among those unwilling to attend a self-paid colonoscopy. CONCLUSION： Raising the public awareness of CRC and its screening, integrating CRC screening into the health care system, and using a painless colonoscopy would increase its screening rate.     

Projected national impact of colorectal cancer screening on clinical and economic outcomes and health services demand

BACKGROUND & AIMS: Colorectal cancer (CRC) screening is effective and cost-effective, but the potential national impact of widespread screening is uncertain. It is controversial whether screening colonoscopy can be offered widely and how emerging tests may impact health services demand. Our aim was to produce integrated, comprehensive estimates of the impact of widespread screening on national clinical and economic outcomes and health services demand. METHODS: We used a Markov model and census data to estimate the national consequences of screening 75% of the US population with conventional and emerging strategies. RESULTS: Screening decreased CRC incidence by 17%-54% to as few as 66,000 cases per year and CRC mortality by 28%-60% to as few as 23,000 deaths per year. With no screening, total annual national CRC-related expenditures were 8.4 US billion dollars. With screening, expenditures for CRC care decreased by 1.5-4.4 US billion dollars but total expenditures increased to 9.2-15.4 US billion dollars. Screening colonoscopy every 10 years required 8.1 million colonoscopies per year including surveillance, with other strategies requiring 17%-58% as many colonoscopies. With improved screening uptake, total colonoscopy demand increased in general, even assuming substantial use of virtual colonoscopy. CONCLUSIONS: Despite savings in CRC care, widespread screening is unlikely to be cost saving and may increase national expenditures by 0.8-2.8 US billion dollars per year with conventional tests. The current national endoscopic capacity, as recently estimated, may be adequate to support widespread use of screening colonoscopy in the steady state. The impact of emerging tests on colonoscopy demand will depend on the extent to which they replace screening colonoscopy or increase screening uptake in the population.     

Systematic review of colorectal cancer screening guidelines for average-risk adults: Summarizing the current global recommendations

AIM To summarize and compare worldwide colorectal cancer(CRC) screening recommendations in order to identify similarities and disparities.METHODS A systematic literature search was performed using MEDLINE, EMBASE, Scopus, CENTRAL and ISI Web of knowledge identifying all average-risk CRC screening guideline publications within the last ten years and/or position statements published in the last 2 years. In addition, a hand-search of the webpages of National Gastroenterology Society websites, the National Guideline Clearinghouse, the BMJ Clinical Evidence website,Google and Google Scholar was performed. RESULTS Fifteen guidelines were identified. Six guidelines were published in North America, four in Europe, four in Asia and one from the World Gastroenterology Organization. The majority of guidelines recommend screening average-risk individuals between ages 50 and 75 using colonoscopy(every 10 years), or flexible sigmoidoscopy(FS, every 5 years) or fecal occult blood test(FOBT, mainly the Fecal Immunochemical Test, annually or biennially). Disparities throughout the different guidelines are found relating to the use of colonoscopy, rank order between test, screening intervals and optimal age ranges for screening. CONCLUSION Average risk individuals between 50 and 75 years should undergo CRC screening. Recommendations for optimal surveillance intervals, preferred tests/test cascade as well as the optimal timing when to start and stop screening differ regionally and should be considered for clinical decision making. Furthermore, local resource availability and patient preferences are important to increase CRC screening uptake, as any screening is better than none.