大肠癌普查互补性筛检方案的研究

为减少序贯普查便隐血试验（ＦＯＢＴ）对大肠癌筛检的漏检率，我们联合采用人血红蛋白抗血清包被的含Ａ蛋白葡萄球菌（ＳＰＡ）进行免疫便隐血试验（ＳＰＡ试验）和直肠粘液Ｔ抗原检测（即Ｓｈａｍｓ试验）用于大肠癌普查初筛，以验证两者的互补效果。在７７４０例无症状人群中，阳性率ＳＰＡ试验为１１．１％Ｓ，ｈａｍｓ试验为８．９％共１４９８例阳性者行纤维结肠镜检查，检出大肠癌１１例，腺瘤８８例。其中ＳＰＡ试验中仅９例癌、５５例腺瘤呈阳性结果。Ｓｈａｍｓ试验中８例癌、５１例腺瘤阳性。由于癌肿有时对两种试验的阳性结果不重叠，因此结合两种试验可使癌检出率从单一初筛试验的８１．８％（ＳＰＡ试验）或７２．７％（Ｓｈａｍｓ试验）提高到９０．９％对腺瘤检出的互补作用则更为明显。本实验结果提示单纯以ＦＯＢＴ作为初筛指标进行序贯普查有一定局限性，利用对癌的检出具有不同机制和检出效果的初筛试验进行互补性普查，可减少大肠癌及癌前病变的漏检率。     

大肠癌普查互补筛检方案的研究

为减少贯普查便隐血试验大肠癌筛检的漏检率，我们联合采用人血红蛋白抗血清包被的含Ａ蛋白葡萄球菌进行免疫便隐血试验和直肠粘液Ｔ抗原检测用于大肠癌普查初筛，以验证两者的互补效果，在７７４０例无症状人群中，阳性率ＳＰＡ试验为１１．１％，Ｓｈａｍｓ试验为８．９％，共１４９８例阳性者行纤维结肠镜检查，检出大肠癌１１例，腺瘤８８例，其中ＳＰＡ试验中仅９例癌，５５例腺瘤呈阳性结果，Ｓｈａｍｓ试验中８例癌，５１例腺     

高龄人群连续性大肠肿瘤普查的必要性和可行性

目的　探讨高龄人群结肠癌普查的可行性和必要性。方法　对１６３８ 名无症状老年人（６０ － ９０ 岁） 连续１１年每年行粪便序贯隐血筛检（ＳＦＯＢＴ） 一次，ＳＦＯＢＴ 阳性者予全结肠肠镜检查。结果　每年普查率约为８０ ％ ，计１３１０ 人。共检出大肠癌１２ 例，大肠腺瘤１３０ 例，其年发病率分别为６６－６０／１０ 万及７２－１５／１０ 万。在１１ 年连续筛检的个体中，检出大肠癌３ 例。未连续检查的个体中，检出大肠癌９ 例。１３０ 例大肠腺瘤均于结肠镜下切除，随访１１ 年无１ 例癌变。结论　高龄人群是大肠癌的高危人群，大肠癌普查可提高可愈癌和腺瘤的检出。因此提高筛检的敏感性和依从性是可治愈大肠癌检出的关键因素。切除大肠腺瘤可预防大肠癌的发生     

RT-PCR寻找大肠癌患者外周血早期分子标记物的研究

目的:探求大肠癌患者早期诊断的外周血分子标记物,为大肠癌临床筛查提供早期、可靠、简便易行的有效方法．方法:采用RT-PCR检测28例大肠癌、8例腺瘤中重度不典型增生、18例腺瘤轻度不典型增生、11例炎性息肉患者和10例正常对照者的外周血中CK-20,GST-π,hTERT,survivin及 skp2的mRNA表达情况．结果:大肠癌、腺瘤中重度不典型增生、腺瘤轻度不典型增生、炎性息肉组和正常对照组hTERT mRNA表达的阳性率分别为 82．1％(23/28)、87．5％(7/8)、27．8％(5/11)、 9．1％(1/11)、10％(1/10),大肠癌组及腺瘤中重度不典型增生组与其他各组之间差别显著 (P<0．05);survivin mRNA在大肠癌、腺瘤中重度不典型增生组、腺瘤轻度不典型增生组的阳性率分别是64．2％(18/28)、50%(4/8)、 11．1％(2/18),炎性息肉组及正常组未见表达, 大肠癌组与腺瘤中重度不典型增生组无差别, 与腺瘤轻度不典型增生组、炎性息肉及正常组之间差别显著(P<0．05);而CK-20,GST-π, skp2 mRNA在各组之间表达无统计学意义(均 P>0．05)．结论:RT-PCR检测大肠癌患者外周血hTERT, survivin mRNA的表达对大肠癌的早期诊断有意义,可望成为早期诊断的分子标记物．     

"序贯粪隐血大肠肿瘤筛检方案"应用价值的再探讨

目的 通过自然人群大肠肿瘤普查了解近年北京市大肠癌发病情况，进一步探讨“序贯粪便隐血大肠癌筛检方案”的有效性和可行性。方法 选定15家医院医疗责任区内48100自然人群为本次普查靶人群。对其中30岁以上的社区或企业职工26827人进行普查登记，并连续进行3d序贯粪隐血检查。隐血阳性者接受结肠镜检查。符合高危条件者，全部接受隐血和肠镜检查。结果 预计普查人为26827人，实际普查人数为19852人，普查率为74％。男女比例为1．05：1。中位年龄50岁。序贯粪隐血阳性率为5．6％，检出大肠癌12例，其中DukesA期4例，B期7例，C期1例。Dukes A B共11例，占全部检出癌的91．66％。40岁以下人群未检出大肠癌，50岁以上人群中，检出大肠癌的比例随年龄升高而逐渐增加。高危人群中检出2例大肠癌，占该人群的0．28％，一般危险人群中检出10例大肠癌，占该人群的0．05％。结论 普查靶人群的大肠癌患病率为36．57／10^5，提示北京市城区有较高的患病率。采用“序贯粪隐血筛检方案”检出了91．66％的早期和较早期癌。提示该方案的有效性和可行性。高危人群和50岁以上的一般危险人群为大肠癌的重点普查对象。     

结直肠癌筛查对结直肠肿瘤早期诊断的意义

背景：我国结直肠癌（CRC）发病率和死亡率呈上升趋势,发病年龄趋于年轻化。目的：分析CRC筛查初筛阳性人群的结肠镜检查结果,探讨高危问卷联合粪便隐血试验的CRC筛查模式对于结直肠肿瘤早期诊断的意义。方法：连续纳入2013年5月—2019年10月参与上海市黄浦区社区CRC筛查,因初筛结果阳性至瑞金医院卢湾分院接受结肠镜检查的高危个体,内镜检查发现病变者取活检或摘除送病理检查。同期因排便习惯改变行结肠镜检查的患者作为对照组。分析两组结直肠肿瘤检出情况以及筛查阳性组的病变特征。结果：共1 329例初筛阳性者纳入研究,结肠镜检查病变总体检出率为63.3%,CRC、息肉和腺瘤性息肉检出率分别为2.6%(34例)、60.7%(807例)和35.2%(468例),均显著高于对照组（n=22 438）的43.6%、1.8%、41.5%和21.6%(P均<0.05)。筛查阳性组病变检出率男性显著高于女性（73.7%对54.2%, P<0.05）,且随年龄增长呈增高趋势（P<0.05）。CRC主要分布于60～79岁年龄组,无性别分布差异,病变直径均≥1 cm;发生异型增生的腺瘤直径亦多≥...     

用抗人结肠癌单克隆抗体检测血清和粪便中大肠癌相关抗原的研究

目的 研究抗人结肠癌MAb检测血清及粪液中癌相关抗原的价值。 方法 采用抗人结肠癌单抗SC_(3A)和SC_6检测47例结直肠癌、33例结直肠腺瘤、15例增生性息肉、14例炎性息肉及60例正常人群的血清和粪便中癌相关抗原。经ELISA双抗体夹心法检测。 结果 血清和粪便阳性率在结直肠癌组分别为66.0％和72.3％;腺瘤组为63.6％和60.6％;增生性息肉组为35.7％和57.1％;炎性息肉组为40.0％和33.3％;而正常对照组仅为11.7％和13.3％。45例大肠癌Dukes分期进行检测,早期癌粪便检测的阳性率为72.2％,而血清为50.0％。 结论 ELISA法检测不仅对大肠癌及癌前病变具有较好的敏感性,而且对早期癌及癌前期病变检测较血清学检测意义更大。此外,随腺瘤不典型增生程度加重而检测阳性率增高。粪便中检测大肠癌相关抗原,方法简便,取材容易,具较好敏感性,对大规模人群普查大肠癌具有一定的应用价值。     

结肠镜普查及随访对老年人早期结直肠癌的诊断价值

目的 通过对老年人进行结肠镜临床普及及随访,提高老年人结直肠癌的防治水平。方法 结合每年查体对2196例60－89岁老年人进行结肠镜临床普查及随访,结肠镜随访1740例,随访率为79．2％。结果 共检出结直肠癌52例,检出率为2．4％,早期结直肠癌19例,占36．5％,结肠镜随访中检出早期结肠癌9例,占随访检出直肠癌20例的45．0％。结直肠癌手术切除率及术后5年生存率分别为97．7％和80．9％。结肠镜插镜成功率为98．9％,并发症的发生率为0．05％。结论 开展老年人结肠镜临床普查及随访,使结直肠癌及癌前病变－－腺瘤性息肉患者得到了早期诊断,提高了早期结直肠癌的检出率及结直肠癌的Ⅱ级防治水平。     

结直肠癌筛查发现的7 408例肠道病变临床特征及病理类型分析

目的 探讨结直肠病变患者临床与病理特征，为结直肠癌早期临床诊断与干预提供依据。 方法 基于2007至2012年海宁市32万余40～74岁目标人群结直肠癌筛查结果，对筛查检出的肠道病变进行临床特征（包括性别、年龄、大小、部位、形态、数目）及病理类型等分析探讨。 结果 共完成初筛286 470例，顺应率88.96％；完成结肠镜检查29 069例，检出肠道病变7 408例，检出率25.48％；男性检出率高于女性（32.62%比19.48%，P＜0.001）；40～49岁组检出率18.30％，70～74岁组检出率35.06％，显示年龄越大检出率越高（P＜0.001）。7 408例肠道病变中，左半结肠约占69.40%，多发性病变占37.23％，＞1.0 cm病变占19.60％。检出结直肠癌205例（早期癌161例、中晚期癌44例），进展期腺瘤1 365例，早诊率为97.20％。手术切除的5 030例病变病理提示腺瘤型及以上病变所占比重最大（63.00％）。直径＞1.5 cm病变癌变率为34.08%。 结论 在高危人群中男性肠道病变检出率明显高于女性，年龄越大检出率越高；病理类型以腺瘤所占比重最高。     

大肠癌患者一级亲属的电子肠镜与粪便潜血试验的筛查结果分析

目的研究大肠癌先证患者的一级亲属的电子肠镜和粪便潜血试验（faecal occult blood testing, FOBT）筛查的临床意义。方法前瞻性分析大肠癌先证患者的一级亲属186例的电子肠镜和FOBT的筛查结果。FOBT应用试纸免疫法和氨基比林化学法。结果在186例亲属的肠镜检查中阳性病变检出率高达80．1％，其中癌前病变占41．1％，恶性疾病占23．6％。而FOBT的检出率只有22．3％，明显低于肠镜的检出率（P〈0．001）。大肠息肉、息肉癌变和大肠癌在一级亲属的检出率分别为56．5％、6．5％和17．2％，在对照组分别为25．7％、0．5％和6．5％，两组比较，P均小于0．001。本组小于40岁的患者占阳性病变的20．1％和恶性病变的17．1％。肠镜检查检出Dukes A期大肠癌18例，占56．3％，B期12例，占37．5％，C期2例，占6．3％，D期0例。所有大肠癌患者均可进行根治性手术切除。结论在大肠癌先证患者的一级亲属中进行结肠镜筛查明显优于FOBT，具有较高的检出率，并可预防大肠癌和早期诊断大肠癌和提高根治手术率。     

直肠粘液T抗原检测及大便潜血试验对肠道病变诊断价值的探讨

目的和方法:对74例住院病人分肠癌组、肠病组、出血与非出血四组,将化学潜血检测(FOB)与SPA免疫潜血试验(SPA)对检测消化道出血的敏感性和特异性进行对比,并将潜血试验与直肠粘液T抗原对大肠癌的诊断价值进行探讨,结果:结果表明T抗原诊断大肠癌阳性预告值100%,阴性预告值为84.6%而SPA诊断大肠癌的阳性预告值及阴性预告值分别为63.2%和80%,证实T抗原对大肠癌的诊断效率(91.7%)极显著高于SPA(66.7%).结论:两种方法联合检测,可提高肠病的检出率,两法同时阳性,恶性病变可能极大.SPA法与FOB法对消化道出血的诊断效率无明显差异,但对消化道出血的特异性,SPA法极显著高于FOB法,FOB法对诊断大肠癌特异性较差,易受饮食、药物等因素干扰,SPB较之有较高的敏感性和特异性,且操作简便、结果判断迅速、重复性好,可作为临床检测消化道出血时推广应用.     

Colorectal cancer screening in Health Examination Centers

OBJECTIVES: The aim of this study was to describe the results of colorectal cancer screening performed in the Health Examination Centers of the French general health insurance system. METHODS: The population consisted of 1,262,833 subjects (52.6% men) aged 50 to 74 years old who attended periodic health consultations from 1998 to 2003 in 89 Health Examination Centers in France. Subjects with increased risk for colorectal cancer and subjects with a positive fecal occult blood test (Hemoccult II') were invited to undergo colonoscopy. Subsequent follow-up and diagnostic data were collected. RESULTS: Prior screening practices for colorectal cancer (recent colonoscopy or fecal occult blood test, local screening campaign) were noted in 18% of the subjects attending Health Examination Center consultations. High risk for colorectal cancer (familial or personal factor) without ongoing surveillance or prior screening was observed in 3% of the study population. A fecal occult blood test was proposed to 79% of the population and of them, 89% effectively performed the test: 3.2% of tests were positive. A follow-up protocol was initiated for 63,357 subjects. A colonic exploration was performed in 69% of high-risk subjects and enabled detection of cancer in 85 and adenomas in 1683. A colonic exploration was performed in 88% of subjects with a positive fecal occult blood test and enabled detection of 674 cancers (positive predictive value of fecal occult blood test (PPV)=4.7%) including 174 Dukes A, and 2618 adenomas (PPV=18%) including 776 adenomas measuring more than 10 mm (PPV=5.4%). CONCLUSION: This study confirms the importance of implementing organized screening practices within Health Examination Centers before undertaking a generalized screen campaign targeting the entire French population.     

Screening des kolorektalen Karzinoms

Colorectal cancer is common and suitable for screening. There is general agreement that screening for colorectal cancer in the asymptomatic population without familial risk should begin at age 50. The different screening methods can be separated into methods that mainly detect cancers (fecal occult blood tests, genetic stool tests, blood tests, and the M2-PK test) and methods that diagnose cancers and polyps (colonoscopy, sigmoidoscopy, CT/MRI colonography, and colon capsule endoscopy). Endoscopic methods enable detection and treatment of preneoplastic adenomas and, thus, make cancer prevention possible. In the current German S3 guideline, colonoscopy is recommended as the preferred screening test. For people unwilling to undergo endoscopic screening, the fecal occult blood test is an alternative. Colonoscopy has been part of the German Cancer Screening Program since 2002.     

Evaluation of the Sensitivity of an Immunochemical Fecal Occult Blood Test for Colorectal Neoplasia

Objectives : This study was designed to evaluate the sensitivity of OC-Hemodia, a immunochemical fecal occult blood test (IFOBT) based on the technique of latex agglutination for early stage colorectal cancer and clinically significant adenomas. Methods : The study was conducted on 885 patients who underwent OC-Hemodia and a colonoscopy. Results : Colorectal cancers were detected in 23 patients (10 Dukes' A, eight Dukes' B, and five Dukes' C or D). Adenomas were detected in 459 patients (16 villous adenomas 433 tubular adenomas with mild or moderate dysplasia, and 10 with severe dysplasia). The sensitivity of OC-Hemodia was 90% for those with Dukes' A colon cancer and 100% for those with Dukes' B, C, or D colon cancer. It was 18.8% for those with villous changes, and 40% for those with severe dysplasia. Conclusions : These results suggest that the IFOBT is not a reliable test for the screening of prenialignant adenomas, although it is useful for detecting early stage colorectal cancers.     

Immunological fecal occult blood test vs. serum ferritin for detection of colorectal neoplasia in high risk asymptomatic population

Introduction: Fecal occult blood tests (FOBT) (biochemical or immunological) are based on the fact that most of the polyps or cancers bleed. Anemia due to iron deficiency is a wellknown sign for colorectal cancer (CRC). Ferritin is frequently used to select candidates for colonoscopy. Objective: To determine and compare the diagnostic value of immunological fecal occult blood test vs. ferritin for the detection of colorectal neoplasia (cancer or polyps) in high-risk patients. Methods: A transversal prospective study at National Cancer Institute, Mexico City, in consecutive asymptomatic subjects at high risk for CRC was performed, comparing two tests (immunological against serum ferritin) with colonoscopy plus histopathology. Both tests were performed in a blindly fashion previous to colonoscopy. Results: Fifty patients were included in the study; twenty-eight patients had colorectal neoplasia (21 CRC, 7 adenomas). All immunologic tests for fecaloccult blood were positive in patients with colorectal lesions (sensitivity, 98%). There was no difference between the mean ferritin levels in patients with CRC or adenomas vs. those with negative colonoscopy (p = 0.58). The cutoff point where significant relationship between serum ferritin levels and colon lesions was established was ?46 ng/mL. In anemic patients with serum ferritin levels <46 ng/mL, the test had a sensitivity 53%, specificity 86%, positive predictive value 83%, and negative predictive value of 59% (p = 0.003). Conclusions: The immunological FOBT is a better diagnostic tool than serum ferritin for screening of colonic neoplasms.     

Survey of internal medicine residents' use of the fecal occult blood test and their understanding of colorectal cancer screening and surveillance

OBJECTIVE: Primary care physicians have imperfect understanding of current colorectal cancer screening guidelines and recommendations. Furthermore, compliance with colorectal cancer screening by internal medicine residents has been demonstrated to be poor. We sought to identify whether current trainees in internal medicine had adequate understanding of colorectal cancer screening and surveillance and test utilization. METHODS: We applied a structured questionnaire about colorectal cancer screening and the use of fecal occult blood tests to 168 internal medicine residents at four accredited programs in the U.S. They were also asked for recommendations about six hypothetical patients who may have been candidates for screening or surveillance. RESULTS: Seventy-one percent identified 50 yr as the currently recommended age to commence screening in an average-risk individual; 64.3% would begin screening with fecal occult blood testing and flexible sigmoidoscopy and 4.8% with colonoscopy. Most perform fecal occult blood testing on stool obtained at digital rectal exam and without prior dietary restrictions. Many use fecal occult blood testing for indications other than colorectal cancer screening. Only 29% recommended colonoscopy to evaluate a positive fecal occult blood test. Most residents plan to be screened for colorectal neoplasia at the appropriate age; significantly more opted for colonoscopy than recommended it for their patients. CONCLUSIONS: Internal medicine residents have many misperceptions regarding colorectal cancer screening and the utility of the fecal occult blood test. Educational efforts should be directed at internal medicine residents, many of whom plan careers in primary care, where most colorectal cancer screening is currently performed.     

Interval faecal occult blood testing in a colonoscopy based screening programme detects additional pathology

BACKGROUND: Colonoscopic based surveillance is recommended for patients at increased risk of colorectal cancer. The appropriate interval between surveillance colonoscopies remains in debate, as is the "miss rate" for colorectal cancer within such screening programmes. AIMS: The main aim of this study was to determine whether a one-off interval faecal occult blood test (FOBT) facilitates the detection of significant neoplasia within a colonoscopic based surveillance programme. Secondary aims were to determine if invitees were interested in participating in interval screening, and to determine whether interval lesions were missed or whether they developed rapidly since the previous colonoscopy PATIENTS: Patients enrolled in a colonoscopic based screening programme due to a personal history of colorectal neoplasia or a significant family history. METHODS: Patients within the screening programme were invited to perform an immunochemical FOBT (Inform). A positive result was followed by colonoscopy; significant neoplasia was defined as colorectal cancer, adenomas either > or =10 mm or with a villous component, high grade dysplasia, or multiplicity (>/=3 adenomas). Participation rates were determined for age, sex, and socioeconomic subgroups. Colonoscopy recall databases were examined to determine the interval between previous colonoscopy and FOBT offer, and correlations between lesion characteristics and interval time were determined. RESULTS: A total of 785 of 1641 patients invited (47.8%) completed an Inform kit. A positive result was recorded for 57 (7.3%). Fifty two of the 57 test positive patients completed colonoscopy; 14 (1.8% of those completing the FOBT) had a significant neoplastic lesion. These consisted of six colorectal cancers and eight significant adenomas. CONCLUSIONS: A one off immunochemical faecal occult blood test within a colonoscopy based surveillance programme had a participation rate of nearly 50% and appeared to detect additional pathology, especially in patients with a past history of colonic neoplasia.     

粪便转铁蛋白和免疫粪隐血试验在结直肠癌筛查中效能的比较

目的评估粪便转铁蛋白(TF)和免疫粪隐血试验(IFOBT)在筛查结直肠癌中的效能。方法筛查对象为1 943例无症状受试者。收集1次粪便标本,同时用于TF和IFOBT检测。两者任一结果为阳性,即通知受试者行结肠镜检查。分别计算TF、IF-OBT和两者联合检测的性能指标。结果共有1 737例受试者接受TF和IFOBT检查,其中251例(14.5%)至少1项结果为阳性。共有193例接受结肠镜检查,共发现3例结直肠癌和43例进展期腺瘤。与单独使用IFOBT相比,TF和IFOBT联合检测(并联)明显提高了结直肠癌和进展期腺瘤的检出率(2.6%vs 1.6%,P=0.034)。结论 TF和IFOBT联合检测能提高筛查时结直肠癌和进展期腺瘤的检出率。     

Detection rate of immunochemical fecal occult blood test for colorectal adenomatous polyps with severe dysplasia

This study was conducted to assess the accuracy of an immunochemical occult blood test for detecting colorectal adenomas with severe dysplasia, and to determine the relationship between the grading of adenomatous dysplasia and the results of this test. Sixteen colorectal adenomas under 1cm with severe dysplasia, 65 adenomas 1 cm or larger with severe dysplasia, 65 adenomas under 1 cm with mild-to-moderate dysplasia, 65 adenomas 1 cm or larger with mild-to-moderate dysplasia, 65 colorectal cancers and 130 healthy controls were investigated. Each subject was tested with an immunochemical fecal occult blood test on 3 consecutive days, and the accuracy of the test was evaluated. The detection rate of this test was 13% for severe dysplasia under 1 cm 45% for severe dysplasia 1cm or more, 17% for mild-to-moderate dysplasia under 1 cm, 40% for mild-to-moderate dysplasia 1 cm or more, and 89% for colorectal cancers, and the false positive rate was 5%, showing a significant difference in the detection rate between severe dysplasias 1 cm or more and those under 1 cm (P<0.05) as well as a significant difference between severe dysplasias 1cm or more and mild-to-moderate dysplasia under 1 cm (P<0.01), and between cancers and adenomas (P<0.001), whereas there was no significant difference between the detection rates for severe dysplasia 1 cm or more and mild-to-moderate dysplasia 1 cm or more. These results indicate that there is no association between the detection rate of this immunochemical occult blood test for adenomas and the grade of adenomatous dysplasia.     

Fecal occult blood and flexible sigmoidoscopy screening for colorectal cancer: modeling the impact on colonoscopy requirements and cancer detection rates

AiM: The aim of this study was to estimate the colonoscopy requirements and the likely impact of fecal occult blood and flexible sigmoidoscopy screening on the detection of colorectal cancer by using previously published data. METHODS: Fecal occult blood and flexible sigmoidoscopy screening programs were applied to the 2.04 million subjects aged 50-65 years, at a participation rate of 40%. The following strategies were evaluated: Fecal occult blood testing with colonoscopy follow up of all positive tests; flexible sigmoidoscopy with colonoscopy follow up of all adenomatous polyps; and flexible sigmoidoscopy with colonoscopy follow up of all adenomatous polyps > 10 mm in size. RESULTS: The fecal occult blood program detected 5.6% of all colorectal cancer cases at a rate of 2,914 colonoscopies/percentage of detection of colorectal cancer. The flexible sigmoidoscopy program detected 14% of all colorectal cancer cases at a rate of 8,160 colonoscopies/percentage of detection of colorectal cancer. The flexible sigmoidoscopy program with follow up of adenomatous polyps > 10 mm in size detected 13% of all colorectal cancer cases at a rate of 1,230 colonoscopies/percentage of detection of colorectal cancer. CONCLUSIONS: Flexible sigmoidoscopy screening followed by colonoscopic follow up of adenomatous polyps > 10 mm in size is the most efficient screening strategy in terms of colonoscopies generated and cases of colorectal cancer detected.