医院就诊人群与普查人群中大肠癌患者临床资料的比较

背景:在我国有无必要开展大肠癌普查仍存在一定争议。目的:比较、分析医院就诊人群与普查人群中大肠癌患者临床资料的异同,探讨普查在大肠癌早期诊断中的作用。方法:就诊组:由协作组各成员医院按统一设计的调查表,前瞻性地登记2002年4月1日～2003年3月31日到医院就诊,并接受结肠镜检查的大肠癌患者的全部临床资料。普查组:采用“序贯粪便隐血筛检技术”,于2001年3～6月对北京地区约2万名35岁以上的自然人群进行大肠癌普查。两组大肠癌患者的诊断均经术后病理检查证实。结果:就诊组和普查组患者中,≥50岁者分别占81.9%和83.3%。就诊组DukesA、B期患者占41.1%,普查组占91.7%(P<0.001)。普查人群中存在大肠癌高危因素者的大肠癌检出率为0.28%,无高危因素者的检出率为0.05%(P<0.001)。就诊组中,内镜表现为隆起型病变者44.7%是DukesA、B期患者,溃疡型病变者仅10.0%是DukesA、B期患者(P<0.001);DukesA、B期患者的粪便隐血试验阳性率为78.5%,C、D期患者为81.9%(P>0.05),提示粪便隐血试验阳性率与大肠癌分期无关;DukesC、D期患者的血清CEA阳性率显著高于A、B期患者(P=0.019);高、中分化癌中DukesA、B期患者占51.8%,低分化癌中DukesA、B期患者仅占26.5%(P<0.001)。结论:近年北京地区的大肠癌发病率较以前明显上升     

开展大肠肿瘤“伺机性筛查”,提高早诊早治水平

大肠癌在中国呈上升趋势,筛查是早期发现、早期诊断的最佳手段。粪隐血试验(FOBT)以及肠镜检查是最有效的筛查方法。"伺机性筛查"(一种新的、基于临床的筛查模式)符合现阶段我国国情和政策,有必要制定我国大肠癌"伺机性筛查"的指导方案(或共识意见)。此外,应提高内镜下早期发现、早期诊断大肠癌的技术及水平。     

A questionnaire-based survey on screening for gastric and colorectal cancer by physicians in East asian countries in 2010

Background: The incidence of gastric cancer (GC) is high, and colorectal cancer (CRC) has significantly increased in Asian countries. Aim: To examine the current screening for GC and CRC within East Asia by means of a questionnaire survey. Methods: Representative members of the Committee of the International Gastrointestinal Consensus Symposium provided a questionnaire to physicians in six East Asian countries. Results: A total of 449 physicians participated in this survey. In all countries, more than 70% of physicians started GC screening between 40 and 59 years. The most popular method to screen for GC was endoscopy (92.7%), but combination methods such as Helicobacter pylori (HP) antibody, barium X-ray, and tumor marker with endoscopy differed by country. For HP-positive individuals, most physicians screened every year by endoscopy, and for individuals post-HP eradication, about half of physicians (56.3%) thought there was a need to follow-up with GC screening. Among all physicians, the most common age to start CRC screening was in the 40s (39.8%) and 50s (40.9%). Based on the American Cancer Society Recommendations, a fecal occult blood test every year was the most popular method for CRC screening overall. However, among each country, this test was most popular in only Japan (76.9%) and Indonesia. In other countries, sigmoidoscopy every 5 years and total colonoscopy every 10 years were the most popular methods. Conclusion: There are similarities and differences in the screening of GC and CRC among East Asian countries.     

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.     

Comparing 3 Values Clarification Methods for Colorectal Cancer Screening Decision-Making: A Randomized Trial in the US and Australia

Purpose

To compare the effects of three methods of values clarification (VCM): balance sheet; rating and ranking; and a discrete choice experiment (DCE) on decision-making about colorectal cancer (CRC) screening among adults in the US and Australia.

Methods

Using online panels managed by a survey research organization in the US and Australia, we recruited adults ages 50–75 at average risk for CRC for an online survey. Those eligible were randomized to one of the three VCM tasks. CRC screening options were described in terms of five key attributes: reduction in risk of CRC incidence and mortality; nature of the screening test; screening frequency; complications from screening; and chance of requiring a colonoscopy (as initial or follow-up testing). Main outcomes included self-reported most important attribute and unlabeled screening test preference by VCM and by country, assessed after the VCM.

Results

A total of 920 participants were enrolled; 51 % were Australian; mean age was 59.0; 87.0 % were white; 34.2 % had a 4-year college degree; 42.8 % had household incomes less than $45,000 USD per year; 44.9 % were up to date with CRC screening. Most important attribute differed across VCM groups: the rating and ranking group was more likely to choose risk reduction as most important attribute (69.8 %) than the balance sheet group (54.7 %) or DCE (49.3 %), p < 0.0001; most important attribute did not vary by country (p = 0.236). The fecal occult blood test (FOBT)-like test was the most frequently preferred test overall (55.9 %). Unlabeled test choice did not differ meaningfully by VCM. Australians were more likely to prefer the FOBT (AU 66.2 % vs. US 45.1 %, OR 2.4, 95 % CI 1.8, 3.1). Few participants favored no screening (US: 9.2 %, AU: 6.2 %).

Conclusions

Screening test attribute importance varied by VCM, but not by country. FOBT was more commonly preferred by Australians than by Americans, but test preferences were heterogeneous in both countries.

Electronic supplementary material

The online version of this article (doi:10.1007/s11606-013-2701-0) contains supplementary material, which is available to authorized users.KEY WORDS: values clarification, colorectal cancer screening, patient decision support     

The intelligent,painless, “germ-free” colonoscopy: A Columbus’ egg for increasing population adherence to colorectal cancer screening?

Colorectal cancer (CRC) represents a major cause of morbidity and mortality. Although it is widely accepted that CRC screening in average risk populations lowers CRC incidence and mortality, a disappointedly low adherence rate to both faecal occult blood testing and colonoscopy-based screening programs has been observed in Italy and in other European countries. Main reasons for the low acceptance of colonoscopy-based CRC screening has been ascribed to lack of recommendations given by general practitioners, fear of discomfort or complications, embarrassment, and avoidance of unpleasant preparation.     

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.     

Perspectives of colorectal cancer screening in Germany 2009

Adequate screening methods can decrease colorectal cancer (CRC) mortality. The guaiac test for fecal occult-blood (FOBT) is part of the German CRC Screening Program since 1970 and has evidence level Ia. In randomized multicenter-studies FOBT has an average sensitivity of 24% and decreases CRC mortality up to 30%. Immunological tests for human haemoglobin (iFOBT) show better performance characteristics than guaiac FOBT, with augmented sensitivity and specificity. However, the single tests show wide differences in diagnostic performance and iFOBT is not yet covered by insurance companies although it should replace the guaiac test for CRC screening. Visual colonoscopy, which was introduced to the German National Cancer Screening Program in 2002, is the gold standard for the diagnosis of colorectal neoplasia. From 2003 to 2007 more than 2.8 million examinations have been documented in Germany. The prevalence of adenomas is around 20% and of CRC about 0.7% to 1.0% of the screenings. Seventy percent of the carcinomas detected during screening are in an early stage (UICC I and II). Furthermore, screening colonoscopy is a cost saving procedure with a low complication rate (0.25% overall). Insurance companies save 216€ for each screening colonoscopy mainly by prevention of neoplasia due to polypectomy. In Germany, virtual colonography by computed tomography (CT) or magnetic resonance imaging still lacks standardization of the hard and software. In experienced centres the sensitivity for CRC and large polyps of CT colonography is comparable to colonoscopy but in meta-analyses the ranking is lower. New technologies like computer-aided colonoscopies with sheath or double balloon techniques are coming up as well as capsule colonoscopy, which sensitivity for large polyps is about 70%. Advised by his physician, the patient can choose his most acceptable examination method from this whole set of screening tools.     

Colorectal cancer population screening programs worldwide in 2016: An update

Colorectal cancer(CRC)is the third most commonly diagnosed cancer in the world.The incidence and mortality show wide geographical variations.Screening is recommended to reduce both incidence and mortality.However,there are significant differences among studies in implementation strategies and detection.This review aimed to present the results and strategies of different screening programs worldwide.We reviewed the literature on national and international screening programs published in Pub Med,on web pages,and in clinical guidelines.CRC Screening programs are currently underway in most European countries,Canada,specific regions in North and South America,Asia,and Oceania.The most extensive screening strategies were based on fecal occult blood testing,and more recently,the fecal immunochemical test(FIT).Participation in screening has varied greatly among different programs.The Netherlands showed the highest participation rate(68.2%)and some areas of Canada showed the lowest(16%).Participation rates were highest among women and in programs that used the FIT test.Men exhibited the greatest number of positive results.The FIT test has been the most widely used screening program worldwide.The advent of this test has increased participation rates and the detection of positive results.     

Cost-effectiveness of colorectal cancer screening

Colorectal cancer (CRC) screening in France is based on a faecal occult blood test every two years in average risk subjects 50-74 years of age while other endoscopic or non-endoscopic screening methods are used in Europe and in the USA. Beside the reduced incidence of and mortality from CRC found in available studies, cost-effectiveness data need to be taken into account. Because of the delay between randomized controlled trials and clinical results, transitional probabilistic models of screening programs are useful for public health policy makers. The aim of the present review was to promote the implementation of cost-effectiveness studies, to provide a guide to analyze cost-effectiveness studies on CRC screening and, to propose a French cost effectiveness study comparing CRC screening strategies. Most of these trials were performed by US or UK authors and demonstrate that the incremental cost-effectiveness ratio varies between 5 000 and 15 000 US dollars/one year life gained, with wide variations: these results were highly dependent on the unit costs of the different devices as well as the predictive values of the screening tests. Although CRC screening programs have been implemented in several administrative districts of France since 2002, and the results of these randomized controlled trials using fecal occult blood have been updated, cost-effectiveness criteria need to be integrated; especially since the results of screening campaigns based on other tools such as flexible sigmoidoscopy should be available in 2007.     

New European initiatives in colorectal cancer screening: Budapest Declaration. Official appeal during the Hungarian Presidency of the Council of the European Union under the Auspices of the United European Gastroenterology Federation, the European Association for Gastroenterology and Endoscopy and the Hungarian Society of Gastroenterology

Colorectal cancer (CRC) is the second most common newly diagnosed cancer and the second most common cause of death in the European Union (EU). CRC is an enormous health and economic burden. Early detection and prevention have the possibility of reducing this burden significantly. Many cancer-associated deaths can be avoided through early detection by high-quality colorectal screening programs followed by appropriate treatment. Under the auspices of the United European Gastroenterology Federation (UEGF), the European Association for Gastroenterology and Endoscopy, the Hungarian Society of Gastroenterology and the Hungarian College of Gastroenterology, the 'Budapest Declaration' (2011) was an accepted official scientific program during the Hungarian Presidency of the Council of the European Union. The Budapest Declaration follows the Munich Declaration (2001), the Brussels Declaration (2007), the Transatlantic Declaration (2009), the Barcelona Declaration (2010), the written declaration of CRC screening, a joint initiative with European Parliamentarians coordinated by the UEGF, and finally, the 'European Guidelines for Quality Assurance in Colorectal Cancer Screening and Diagnosis'. The 'Budapest Declaration' together with previous declarations aims to urge the national and supranational healthcare decision makers to launch new Europe-wide initiatives to establish high-quality CRC programs to achieve optimal efficiency in CRC screening. In case of implementation of the proposals, actions and conditions recommended, we can achieve that one of the basic principles of the EU - the chance of equal access - be realized in member states with respect to the prevention of CRC and reduction of cancer-related mortality. To better achieve this goal, we propose to establish an UEGF joint committee, with one participant representing each EU member state to coordinate and supervise the implementation of CRC screening.     

Colorectal cancer screening

Colorectal cancer (CRC) is the third most common cause of cancer death worldwide and a major health problem. In this review, the different approaches for CRC screening will be outlined with emphasis on evidence-based medicine. Evidence from randomized trials on the effectiveness of CRC screening is summarized. Several screening tools for CRC are available. They can be categorized according to their mode of action: early detection tools such as the faecal occult blood test (FOBT) and cancer prevention tools such as flexible sigmoidoscopy and colonoscopy. Meta-analyses of randomized trials show that FOBT screening reduces CRC mortality by 16% (risk ratio 0.84; 95% confidence interval (CI) 0.78-0.9) compared with 30% (risk ratio 0.7; 95% CI 0.6-0.81) for flexible sigmoidoscopy screening. FOBT screening is cheap and noninvasive, but results in large numbers of false-positive tests and needs to be repeated frequently. Flexible sigmoidoscopy is more invasive, but is effective for once-only screening. Although colonoscopy screening is used in some countries, no randomized trials have been conducted to estimate its benefit, and therefore, it should not be recommended at the present time. Faecal occult blood test and flexible sigmoidoscopy are the two CRC screening tools that can be recommended as they have been proven to reduce CRC mortality. Colonoscopy has the potential to be superior to FOBT and flexible sigmoidoscopy, but needs to be evaluated in randomized trials before any recommendation can be provided.     

Design,Organization and Management of a Controlled Population Screening Study for Detection of Colorectal Neoplasia: Attendance Rates in the NORCCAP Study (Norwegian Colorectal Cancer Prevention)

Background: In the past three decades, the incidence of colorectal cancer (CRC) in Norway has doubled, surpassing all other Nordic countries for both men and women to become the most frequently diagnosed cancer. A small-scale, randomized study on flexible sigmoidoscopy (FS) screening in Telemark, Norway, has shown a reduction in accumulated CRC incidence after 13 years. The aim of our study was to evaluate the effect on CRC mortality and morbidity by screen detection of CRC and removal of precursor lesions (polypectomy), and to test out the management and organization mimicking a countrywide screening service. A total of 13,823 men and women (1:1), age 55-64 years, were drawn randomly from the population registries in Oslo (urban) and the county of Telemark (mixed urban and rural) and invited to have a screening examination. The rest of the relevant age cohorts constituted the control groups. In the screening group, 535 individuals were excluded according to exclusion criteria, rendering 13,288 individuals eligible for screening examination. Methods: A once only screening model was used. In the screening group, individuals were randomized to have a once only FS or a combination of FS and faecal occult blood test (FOBT). Results: The overall attendance rate was 8,849 out of 13,288 (67%); 73% in Telemark and 60% in Oslo. Attendance for FS only was 68% and 65% for combined FS&FOBT. Conclusions: The present FS/FS&FOBT screening study obtained a high acceptance rate for both screening modalities. The attendance rate was stable throughout the trial, suggesting an acceptable model for management of future countrywide screening.     

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.     

自然人群序贯粪隐血试验连续性结直肠癌普查的队列研究：19年结果分析

筛查是早期发现结直肠癌（CRC）的重要手段。目的：评价自然人群序贯粪隐血试验（SFOBT）连续性CRC普查在提高早期CRC检出率、患者长期生存率和降低CRC发生率方面的作用。方法：于1987～2005年，应用SFOBT对一组基本固定的中老年人群（初次普查人群3002例）行连续性CRC普查。每1～2年接受一次普查者计入普查组，连续3年或3年以上未接受普查者计入未普查组。FOBT阳性者行结肠镜检查。于北京军区总医院行手术治疗的1033例CRC患者作为对照组。结果：19年中普查人群共发生CRC52例，总CRC发生率为90．4／10万人·年。普查组共检出CRC25例，漏诊7例，CRC检出率为57．6／10万人·年，发生率为73．8／10万人·年；未普查组发生CRC20例，发生率为141．4／10万人·年。普查组DukesA／B期患者比例（95．5％对31．2％和43．9％，P〈0．05）和5年生存率（77．8％对33．3％和39．8％，P〈0．05）显著高于未普查组和对照组。SFOBT筛查CRC的19年总敏感性为90．6％，特异性为98．0％，阳性预测值为3．2％，阴性预测值为99．99％。结论：SFOBT应用于自然人群连续性普查可提高早期CRC检出率和患者5年生存率。切除普查中发现的腺瘤可明显降低CRC发生率。该筛查方案具有较高的敏感性和特异性，但仍需高度关注其结肠镜检查的依从性.     

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。     

Colon cancer screening: which non-invasive filter tests?

The following non-invasive stool tests for colorectal cancer (CRC) screening exist: guaiac or immunochemical fecal occult blood testing (FOBT), genetic stool tests and the M2-PK. Currently the most widely used tests are guaiac-based (gFOBT). Several randomized controlled trials have shown that gFOBT are able to achieve a reduction in CRC-related mortality. This reduction is achieved by detecting asymptomatic cancers at an early stage with a better prognosis. However, gFOBT have a low sensitivity for colorectal adenomas and are thus unlikely to be able to reduce the incidence of CRC. Furthermore, gFOBT are not specific for human blood and can be influenced by external factors. Immunochemical tests (iFOBT) only detect human blood in the stool. In two recent randomized studies from the Netherlands comparing guaiac and immunochemical tests in the asymptomatic population, iFOBT were found to detect more cancers than gFOBT. Furthermore, iFOBT were able to detect more advanced adenomas thus having the potential to be able to reduce the incidence of CRC as well as CRC-related mortality. In the recently released European CRC screening guidelines, iFOBT are considered the screening test of choice. Several questions remain however. It is currently unknown what the optimal cut-off value for an iFOBT to be considered positive should be and what the number of stool samples is that are required. Genetic stool tests detect mutations in stool that can be found in CRC. The original test testing for 21 genetic changes was found to be superior to gFOBT for the detection of cancers. However, the sensitivity was moderate (51.6%) and the sensitivity for advanced adenomas was low. In the meantime the test has been modified improving DNA extraction and reducing the number of mutations tested for as well as including a methylation marker. The efficacy of the modified test in the screening population is unknown. M2-PK is an isomer of the enzyme pyruvate kinase that is involved in glycolysis. Studies have found a good sensitivity for cancers, a low sensitivity for advanced adenomas with a specificity of around 80%. Further studies in the screening population are required.     

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.     

Screening for colorectal cancer: implications for UK and European initiatives

Abstract Colorectal cancer (CRC) is the third most common cancer after lung and prostate cancers, and is the second most common cancer in women in the United Kingdom (UK) after breast cancer. The disease is well suited for prevention with screening programs. CRC is invariably fatal when diagnosed at an advanced stage but curable when diagnosed early, since it passes through a detectable asymptomatic stage. Screening tests with varying degrees of sensitivity and specificity are available. Prior to implementation of a nationwide national programme in the UK, trials are underway to identify the most sensitive and specific screening modality, and to address patient acceptability and resource implications. Screening for CRC using faecal occult blood (FOB) tests may be feasible. There is evidence to show that this modality saves lives at a cost similar to the breast screening programme currently underway in the UK. One-off flexible sigmoidoscopy is an alternative to FOB screening, and pilot data suggest that the technique is logistically feasible in the UK; a multicentre randomised trial is currently underway. Total colonoscopy is the gold standard test, but at present no large randomised controlled trials support this strategy. Colonoscopy is expensive and labour-intensive, and training issues need to be addressed. At the present time, tailored screening (in which intensity is adjusted for individual risk) appears reasonable. FOB and flexible sigmoidoscopy are cost effective but vary in sensitivity and specificity. Public education programmes are essential for any screening strategy to be effective.