Fecal occult blood screening in the Minnesota study: sensitivity of the screening test

Projected Colorectal Cancer Incidence and Mortality Based on Observed Adherence to Colonoscopy and Sequential Stool-Based Screening

INTRODUCTION

Modeling supporting recommendations for colonoscopy and stool-based colorectal cancer (CRC) screening tests assumes 100% sequential participant adherence. The impact of observed adherence on the long-term effectiveness of screening is unknown. We evaluated the effectiveness of a program of screening colonoscopy every 10 years vs annual high-sensitivity guaiac-based fecal occult blood testing (HSgFOBT) using observed sequential adherence data.

METHODS

The MIcrosimulation SCreening ANalysis (MISCAN) model used observed sequential screening adherence, HSgFOBT positivity, and diagnostic colonoscopy adherence in HSgFOBT-positive individuals from the National Colonoscopy Study (single-screening colonoscopy vs ≥4 HSgFOBT sequential rounds). We compared CRC incidence and mortality over 15 years with no screening or 10 yearly screening colonoscopy vs annual HSgFOBT with 100% and differential observed adherence from the trial.

RESULTS

Without screening, simulated incidence and mortality over 15 years were 20.9 (95% probability interval 15.8-26.9) and 6.9 (5.0-9.2) per 1,000 participants, respectively. In the case of 100% adherence, only screening colonoscopy was predicted to result in lower incidence; however, both tests lowered simulated mortality to a similar level (2.1 [1.6-2.9] for screening colonoscopy and 2.5 [1.8-3.4] for HSgFOBT). Observed adherence for screening colonoscopy (83.6%) was higher than observed sequential HSgFOBT adherence (73.1% first round; 49.1% by round 4), resulting in lower simulated incidence and mortality for screening colonoscopy (14.4 [10.8-18.5] and 2.9 [2.1-3.9], respectively) than HSgFOBT (20.8 [15.8-28.1] and 3.9 [2.9-5.4], respectively), despite a 91% adherence to diagnostic colonoscopy with FOBT positivity. The relative risk of CRC mortality for screening colonoscopy vs HSgFOBT was 0.75 (95% probability interval 0.68-0.80). Findings were similar in sensitivity analyses with alternative assumptions for repeat colonoscopy, test performance, risk, age, and projection horizon.

DISCUSSION

Where sequential adherence to stool-based screening is suboptimal and colonoscopy is accessible and acceptable-as observed in the national colonoscopy study, microsimulation, comparative effectiveness, screening recommendations.

Should video laryngoscopy or direct laryngoscopy be used for adults undergoing endotracheal intubation in the pre-hospital setting? A critical appraisal of a systematic review

The safety and utility of endotracheal intubation by paramedics in the United Kingdom is a matter of debate. Considering the controversy surrounding the safety of paramedic-performed endotracheal intubation, any interventions that enhance patient safety should be evaluated for implementation based on solid evidence of their effectiveness. A systematic review performed by Hansel and colleagues (2022) sought to assess compare video laryngoscopes against direct laryngoscopes in clinical practice. This commentary aims to critically appraise the methods used within the review by Hansel et al (2022) and expand upon the findings in the context of clinical practice.

Screening and prevention of colorectal cancer

Mortality from colorectal cancer is reduced through screening and early detection; moreover, removal of neoplastic lesions can reduce cancer incidence. While understanding of the risk factors, pathogenesis, and precursor lesions of colorectal cancer has advanced, the cause of the recent increase in cancer among young adults is largely unknown. Multiple invasive, semi- and non-invasive screening modalities have emerged over the past decade. The current emphasis on quality of colonoscopy has improved the effectiveness of screening and prevention, and the role of new technologies in detection of neoplasia, such as artificial intelligence, is rapidly emerging. The overall screening rates in the US, however, are suboptimal, and few interventions have been shown to increase screening uptake. This review provides an overview of colorectal cancer, the current status of screening efforts, and the tools available to reduce mortality from colorectal cancer.

Development and Validation of Three Regional Microsimulation Models for Predicting Colorectal Cancer Screening Benefits in Europe

Background. Validated microsimulation models have been shown to be useful tools in providing support for colorectal cancer (CRC) screening decisions. Aiming to assist European countries in reducing CRC mortality, we developed and validated three regional models for evaluating CRC screening in Europe. Methods. Microsimulation Screening Analysis–Colon (MISCAN-Colon) model versions for Italy, Slovenia, and Finland were quantified using data from different national institutions. These models were validated against the best available evidence for the effectiveness of screening from their region (when available): the Screening for COlon REctum (SCORE) trial and the Florentine fecal immunochemical test (FIT) screening study for Italy; the Norwegian Colorectal Cancer Prevention (NORCCAP) trial and the guaiac fecal occult blood test (gFOBT) Finnish population-based study for Finland. When published evidence was not available (Slovenia), the model was validated using cancer registry data. Results. Our three models reproduced age-specific CRC incidence rates and stage distributions in the prescreening period. Moreover, the Italian and Finnish models replicated CRC mortality reductions (reasonably) well against the best available evidence. CRC mortality reductions were predicted slightly larger than those observed (except for the Florentine FIT study), but consistently within the corresponding 95% confidence intervals. Conclusions. Our findings corroborate the MISCAN-Colon reliability in supporting decision making on CRC screening. Furthermore, our study provides the model structure for an additional tool (EU-TOPIA CRC evaluation tool: http://miscan.eu-topia.org) that aims to help policymakers and researchers monitoring or improving CRC screening in Europe.

MIR1246 in body fluids as a biomarker for pancreatic cancer

Pancreatic cancer is an aggressive tumor associated with poor survival, and early detection is important to improve patient outcomes. In the present study, we examined MIR1246 expression as a biomarker of pancreatic cancer. Total RNA was extracted from serum, urine and saliva samples from healthy subjects (n = 30) and patients with pancreatic cancer (n = 41, stage 0–IV). The MIR1246 level in each fluid was analyzed by quantitative reverse transcription-polymerase chain reaction. Significantly higher MIR1246 expression in serum and urine was observed in patients with cancer than in healthy controls. A significant positive correlation was found between serum and urine MIR1246 expression (r = 0.34). Receiver operating characteristic curves were constructed for MIR1246 in all three body fluids. The area under the curve for serum MIR1246 was 0.87 (sensitivity, 92.3%; specificity, 73.3%), and that for urine MIR1246 was 0.90 (sensitivity, 90.2%; specificity, 83.3%). With a cut-off of the control group’s mean plus twice the standard deviation, the sensitivities of MIR1246 in serum and urine for pancreatic cancer were 60.9 and 58.5%, respectively. Combining both serum and urine MIR1246 expression yielded a sensitivity of 85%. These results indicate that MIR246 may be a useful diagnostic biomarker for pancreatic cancer.

The cumulative false-positive rate in colorectal cancer screening: a Markov analysis

BACKGROUND

Faecal occult blood testing is widely used in colorectal cancer screening. However, there is little empirical long-term evidence on the accumulation of false-positive test results over several screening rounds. We aimed to systematically explore and quantify the cumulative false-positive rate for various scenarios of colorectal cancer screening.

METHODS

Using a Markov analysis, we estimated the lifetime cumulative number of false-positive test results (cumFP) per 100 000 50-year-old persons. We varied the screening interval and the specificity of a single screening test and the starting age of screening.

RESULTS

For a test with a specificity of 98% used from 50 to 74 years, the cumFP at age 74 was 26 260 (1-year interval), 15 102 (2-year interval), and 10 819 (3-year interval), respectively. For a test with a specificity of, respectively, 95 and 92% used at a 2-year interval, the cumFP at age 74 was 2.2 times and 3.0 times higher as compared to a test with a specificity of 98%. The cumFP at age 74 was 18% lower for screening persons aged 54-74 years vs. 50-74 years.

CONCLUSION

Our findings quantitatively illustrate the large variation of the cumFP in colorectal cancer screening between screening strategies, which is relevant to informed decision making and adequate resource planning.

Mortality From Postscreening (Interval) Colorectal Cancers Is Comparable to That From Cancer in Unscreened Patients-A Randomized Sigmoidoscopy Trial

BACKGROUND & AIMS

Endoscopic screening for colorectal cancer (CRC) is performed at longer time intervals than the fecal occult blood test or screenings for breast or prostate cancer. This causes concerns about interval cancers, which have been proposed to progress more rapidly. We compared outcomes of patients with interval CRCs after sigmoidoscopy screening vs outcomes of patients with CRC who had not been screened.

METHODS

We performed a secondary analysis of a randomized sigmoidoscopy screening trial in Norway with 98,684 participants (age range, 50-64 years) who were randomly assigned to groups that were (n = 20,552) or were not (n = 78,126) invited for sigmoidoscopy screening from 1999 through 2001; participants were followed up for a median 14.8 years. We compared CRC mortality and all-cause mortality between individuals who underwent screening and were diagnosed with CRC 30 days or longer after screening (interval cancer group, n = 163) and individuals diagnosed with CRC in the nonscreened group (controls, n = 1740). All CRCs in the control group were identified when they developed symptoms (clinically detected CRCs). Analyses were stratified by cancer site. We used Cox regression to estimate hazard ratio (HRs), adjusted for age and sex.

RESULTS

Over the follow-up period, 43 individuals in the interval cancer group died from CRC; among controls, 525 died from CRC. CRC mortality (adjusted HR, 0.98; 95% confidence interval, 0.72-1.35; P = .92), rectosigmoid cancer mortality (adjusted HR, 1.10; 95% confidence interval, 0.63-1.92; P = .74), and all-cause mortality (adjusted HR, 0.99; 95% confidence interval, 0.76-1.27; P = .91) did not differ significantly between the interval cancer group and controls.

CONCLUSIONS

In this randomized sigmoidoscopy screening trial, mortality did not differ significantly between individuals with interval CRCs and unscreened patients with clinically detected CRCs. ClinicalTrials.gov identifier: NCT00119912.

Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society

In the United States, colorectal cancer (CRC) is the fourth most common cancer diagnosed among adults and the second leading cause of death from cancer. For this guideline update, the American Cancer Society (ACS) used an existing systematic evidence review of the CRC screening literature and microsimulation modeling analyses, including a new evaluation of the age to begin screening by race and sex and additional modeling that incorporates changes in US CRC incidence. Screening with any one of multiple options is associated with a significant reduction in CRC incidence through the detection and removal of adenomatous polyps and other precancerous lesions and with a reduction in mortality through incidence reduction and early detection of CRC. Results from modeling analyses identified efficient and model-recommendable strategies that started screening at age 45 years. The ACS Guideline Development Group applied the Grades of Recommendations, Assessment, Development, and Evaluation (GRADE) criteria in developing and rating the recommendations. The ACS recommends that adults aged 45 years and older with an average risk of CRC undergo regular screening with either a high-sensitivity stool-based test or a structural (visual) examination, depending on patient preference and test availability. As a part of the screening process, all positive results on noncolonoscopy screening tests should be followed up with timely colonoscopy. The recommendation to begin screening at age 45 years is a qualified recommendation. The recommendation for regular screening in adults aged 50 years and older is a strong recommendation. The ACS recommends (qualified recommendations) that: 1) average-risk adults in good health with a life expectancy of more than 10 years continue CRC screening through the age of 75 years; 2) clinicians individualize CRC screening decisions for individuals aged 76 through 85 years based on patient preferences, life expectancy, health status, and prior screening history; and 3) clinicians discourage individuals older than 85 years from continuing CRC screening. The options for CRC screening are: fecal immunochemical test annually; high-sensitivity, guaiac-based fecal occult blood test annually; multitarget stool DNA test every 3 years; colonoscopy every 10 years; computed tomography colonography every 5 years; and flexible sigmoidoscopy every 5 years. CA Cancer J Clin 2018;68:250-281. © 2018 American Cancer Society.

Screening by Total Colonoscopy Following Fecal Immunochemical Tests and Determinants of Colorectal Neoplasia in Japanese Men With Alcohol Dependence

Aims

Alcohol consumption increases the risk of colorectal adenoma and cancer. The fecal immunochemical test (FIT) is a widely used screening method for detecting colorectal neoplasia. We evaluated the results of screening and risk factors for colorectal neoplasia in individuals with alcohol dependence.

Methods

Total colonoscopic screening was performed for 1006 Japanese men with alcohol dependence (462 FIT-positive and 544 FIT-negative). Advanced neoplasia was defined as neoplasia ≥10 mm, villous or tubulovillous adenoma, high-grade adenoma, or carcinoma.

Results

The detection rates for non-advanced adenoma, advanced neoplasia and intramucosal or invasive carcinoma were 38.7%, 39.4% and 9.7% for the FIT-positive group, and 33.3%, 10.8% and 2.2% for the FIT-negative group, respectively. Advanced neoplasia, especially carcinoma, was detected more frequently in the distal colon than in the proximal colon in the FIT-positive group. The respective multivariate odds ratios (ORs; 95% confidence interval) for non-advanced adenoma and advanced neoplasia were 2.83 (2.06–3.88) and 9.13 (6.19–13.5) for a positive FIT (vs. negative), 1.68 (1.39–2.02) and 1.83 (1.45–2.30) for age (per +10 years), 1.54 (1.06–2.23) and 1.88 (1.17–3.03) for current smoking (vs. non-smokers), and 1.35 (0.96–1.92) and 1.59 (1.02–2.48) for the presence of marked macrocytosis (mean corpuscular volume ≥106 fl vs. <106 fl). Genetic polymorphisms of alcohol dehydrogenase-1B and aldehyde dehydrogenase-2 did not affect the risk of colorectal neoplasia.

Conclusion

The detection rate for advanced colorectal neoplasia was extremely high in the FIT-positive group but remained high even in the FIT-negative group. An older age, smoking and macrocytosis were predictors of advanced colorectal neoplasia.

Short summary

Total colonoscopic screening was performed for 1006 Japanese alcoholic men (462 fecal immunochemical test [FIT]-positive and 544 FIT-negative). The detection rate for advanced colorectal neoplasia was extremely high in the FIT-positive group (39.4%) and high in the FIT-negative group (10.8%). Ageing, smoking and macrocytosis were predictors of advanced colorectal neoplasia.

Colorectal Cancer Screening: Stool DNA and Other Noninvasive Modalities

Colorectal cancer screening dates to the discovery of pre-cancerous adenomatous tissue. Screening modalities and guidelines directed at prevention and early detection have evolved and resulted in a significant decrease in the prevalence and mortality of colorectal cancer via direct visualization or using specific markers. Despite continued efforts and an overall reduction in deaths attributed to colorectal cancer over the last 25 years, colorectal cancer remains one of the most common causes of malignancy-associated deaths. In attempt to further reduce the prevalence of colorectal cancer and associated deaths, continued improvement in screening quality and adherence remains key. Noninvasive screening modalities are actively being explored. Identification of specific genetic alterations in the adenoma-cancer sequence allow for the study and development of noninvasive screening modalities beyond guaiac-based fecal occult blood testing which target specific alterations or a panel of alterations. The stool DNA test is the first noninvasive screening tool that targets both human hemoglobin and specific genetic alterations. In this review we discuss stool DNA and other commercially available noninvasive colorectal cancer screening modalities in addition to other targets which previously have been or are currently under study.

Study designs for determining and comparing sensitivities of disease screening tests

Objective

To investigate the capability of various study designs to determine the sensitivity of a disease screening test.

Methods

Quantities that can be calculated from these designs were derived and examined for their relationship to true sensitivity (the ability to detect unrecognized disease that would surface clinically in the absence of screening) and overdiagnosis.

Results

To examine the sensitivity of one test, the single cohort design, in which all participants receive the test, is particularly weak, providing only an upper bound on the true sensitivity, and yields no information about overdiagnosis. A randomized design, with one control arm and participants tested in the other, that includes sufficient post-screening follow-up, allows calculation of bounds on, and an approximation to, true sensitivity and also determination of overdiagnosis. Without follow-up, bounds on the true sensitivity can be calculated. To compare two tests, the single cohort paired design in which all participants receive both tests is precarious. The three arm randomized design with post screening follow-up is preferred, yielding an approximation to the true sensitivity, bounds on the true sensitivity, and the extent of overdiagnosis of each test. Without post screening follow-up, bounds on the true sensitivities can be calculated. When an unscreened control arm is not possible, the two-arm randomized design is recommended. Individual test sensitivities cannot be determined, but with sufficient post-screening follow-up, an order relationship can be established, as can the difference in overdiagnosis between the two tests.

FUT2 and FUT3 genotype determines CA19-9 cut-off values for detection of cholangiocarcinoma in patients with primary sclerosing cholangitis

BACKGROUND & AIMS

Allelic variants of fucosyltransferases 2 and 3 (FUT2/3) influence serum levels of CA19-9, a screening parameter commonly used for detection of biliary malignancy in PSC. We aimed at improving diagnostic accuracy of CA19-9 by determining the impact of FUT2/3 genotypes.

METHODS

CA19-9 levels were measured in 433 PSC patients, 41 of whom had biliary malignancy. Genotypes for FUT3 and FUT2 were used to assign patients to one of three groups: A, no FUT3 activity regardless of FUT2 activity; B, both FUT2 and FUT3 activity and C, no FUT2 activity without loss of FUT3 activity. Group-specific cut-off values were determined by Youden's index.

RESULTS

The median CA19-9 values of cancer-free patients were significantly different (p<0.001) in Groups A (2.0U/ml), B (17.0U/ml), and C (37.0U/ml). Biliary malignancy patients in Groups B and C had significantly higher CA19-9 values than cancer-free patients (p<0.001). The optimal cut-off, as determined by ROC analysis, for all patients was 88.5U/ml. Optimal cut-off values in Groups A, B, and C were 4.0U/ml, 74.5U/ml, and 106.8U/ml, respectively. Use of these values improved sensitivity of CA19-9 in Groups B and C. Further, use of group-dependent cut-off values with 90% sensitivity resulted in a 42.9% reduction of false positive results.

CONCLUSIONS

Use of FUT2/3 genotype-dependent cut-off values for CA19-9 improved sensitivity and reduced the number of false positive results.

Evaluating the long-term effect of FOBT in colorectal cancer screening

BACKGROUND

Cancer screening has been effective in detecting tumors early before symptoms appear. However, the effectiveness of the regular fecal occult blood test (FOBT) in colorectal cancer in the long term has not been quantified.

METHODS

We applied the statistical method developed by Wu and Rosner using data from the Minnesota Colon Cancer Control Study (MCCCS). All initially asymptomatic participants were classified into four mutually exclusive groups: true-early-detection, no-early-detection, over-diagnosis, and symptom-free life; human lifetime was treated as a random variable and is subject to competing risks. All participants in the screening program will eventually fall into one of the four outcomes above. Predictive inferences on the percentages of the four outcomes for both genders were made using the Minnesota study data.

RESULTS

Depending on gender, screening frequency and age at the initial screening, for all participants the probability of "symptom-free-life" varies between 95.3% and 96.6%; the probability of "true-early-detection" is 1.9-3.8%; the probability of no-early-detection is 0.3-2.0%; the probability of over-diagnosis is 0.16-0.3%. Among those with colorectal cancer detected by regular FOBT, the probability of over-diagnosis is lower than expected and is between 6% and 9%, with 95% CI (2.5%, 21.3%) for females and (1.9%, 44.7%) for males. The probability of true-early-detection increases as screening interval decreases. The probability of no-early-detection decreases as screening interval decreases.

CONCLUSION

The probability of over-diagnosis among the screen-detected cases is not as high as previously thought. We hope this outcome can provide valuable information on the effectiveness of the FOBT in colorectal cancer detection in the long term.

Preoperative evaluation and oncologic principles of colon cancer surgery

Colorectal cancer is the third most common malignancy in men and women and accounts for 10% of all cancer deaths. The primary risk factor for colorectal cancer is advancing age, but other factors also play a role in its development, including genetic predisposition, smoking, alcohol consumption, obesity, and high-fat, low-fiber diet. Colon cancer survival is primarily related to the stage of disease at diagnosis. The main screening tests for colon cancer are fecal occult blood testing, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. The pre-operative evaluation should include a complete blood count, carcinoembryonic antigen (CEA), colonoscopy, and chest radiograph. Other preoperative evaluations are patient specific or of unproven benefit. The operative procedure should include a bowel preparation, parenteral antibiotics, and deep venous thrombosis prophylaxis. The procedure performed must be tailored to the location of the colon cancer but should include complete, en bloc resection of the cancer and its lymphatic drainage, including locally invaded structures. The bowel margins of resection should be at least 5 cm from the tumor to minimize anastomotic recurrences. Laparoscopic colectomy has been shown to be as safe and effective as open colectomy for the treatment of colon cancer. The use of sentinel lymph node biopsy is feasible but has not yet been proved clinically useful. Surveillance after surgery for colon cancer is necessary to monitor for metastatic disease or local recurrence. Several groups have made surveillance recommendations including office visits, colonoscopy, and CEA monitoring.

A novel hypothesis on the sensitivity of the fecal occult blood test: Results of a joint analysis of 3 randomized controlled trials

BACKGROUND

Estimates of the fecal occult blood test (FOBT) (Hemoccult II) sensitivity differed widely between screening trials and led to divergent conclusions on the effects of FOBT screening. We used microsimulation modeling to estimate a preclinical colorectal cancer (CRC) duration and sensitivity for unrehydrated FOBT from the data of 3 randomized controlled trials of Minnesota, Nottingham, and Funen. In addition to 2 usual hypotheses on the sensitivity of FOBT, we tested a novel hypothesis where sensitivity is linked to the stage of clinical diagnosis in the situation without screening.

METHODS

We used the MISCAN-Colon microsimulation model to estimate sensitivity and duration, accounting for differences between the trials in demography, background incidence, and trial design. We tested 3 hypotheses for FOBT sensitivity: sensitivity is the same for all preclinical CRC stages, sensitivity increases with each stage, and sensitivity is higher for the stage in which the cancer would have been diagnosed in the absence of screening than for earlier stages. Goodness-of-fit was evaluated by comparing expected and observed rates of screen-detected and interval CRC.

RESULTS

The hypothesis with a higher sensitivity in the stage of clinical diagnosis gave the best fit. Under this hypothesis, sensitivity of FOBT was 51% in the stage of clinical diagnosis and 19% in earlier stages. The average duration of preclinical CRC was estimated at 6.7 years.

CONCLUSIONS

Our analysis corroborated a long duration of preclinical CRC, with FOBT most sensitive in the stage of clinical diagnosis.

At what costs will screening with CT colonography be competitive? A cost-effectiveness approach

The costs of computed tomographic colonography (CTC) are not yet established for screening use. In our study, we estimated the threshold costs for which CTC screening would be a cost-effective alternative to colonoscopy for colorectal cancer (CRC) screening in the general population. We used the MISCAN-colon microsimulation model to estimate the costs and life-years gained of screening persons aged 50-80 years for 4 screening strategies: (i) optical colonoscopy; and CTC with referral to optical colonoscopy of (ii) any suspected polyp; (iii) a suspected polyp >or=6 mm and (iv) a suspected polyp >or=10 mm. For each of the 4 strategies, screen intervals of 5, 10, 15 and 20 years were considered. Subsequently, for each CTC strategy and interval, the threshold costs of CTC were calculated. We performed a sensitivity analysis to assess the effect of uncertain model parameters on the threshold costs. With equal costs ($662), optical colonoscopy dominated CTC screening. For CTC to gain similar life-years as colonoscopy screening every 10 years, it should be offered every 5 years with referral of polyps >or=6 mm. For this strategy to be as cost-effective as colonoscopy screening, the costs must not exceed $285 or 43% of colonoscopy costs (range in sensitivity analysis: 39-47%). With 25% higher adherence than colonoscopy, CTC threshold costs could be 71% of colonoscopy costs. Our estimate of 43% is considerably lower than previous estimates in literature, because previous studies only compared CTC screening to 10-yearly colonoscopy, where we compared to different intervals of colonoscopy screening.

Estimating key parameters in FOBT screening for colorectal cancer

OBJECTIVES

The association between screening sensitivity, transition probability, and individual's age in FOBT for colorectal cancer are explored, for both males and females.

METHODS

We apply the statistical method developed by Wu et al. [1] using the Minnesota colorectal cancer study group data, to make Bayesian inference for the age-dependent screening test sensitivity, the age-dependent transition probability from disease-free to preclinical state, and the sojourn time distribution, for both male and female participants in a periodic screening program. This gives us more information on the effectiveness of the fecal occult blood test in colorectal cancer detection.

RESULTS

The sensitivity appears to increase with age for both genders. However, the posterior mean sensitivity is not monotonic with age for males; it has a peak around age 74. The standard errors of the sensitivity are not monotone either; there is a minimum at age 69 for males and at age 78 for females. The age-dependent transition probability is not a monotone function of age; it has a single maximum at age 72 for males and a single maximum at age 75 for females. The age dependency seems more dramatic for females than for males. The posterior mean sojourn time is 4.08 years for males and 2.41 years for females, with a posterior median of 1.66 years for males and 1.88 years for females. The 95% highest posterior density (HPD) interval is (0.97, 20.28) for males and (1.15, 5.96) for females, which are very large ranges, especially for males. The reason might be that there were fewer men than women in the annual screening program.

CONCLUSION

Reliable estimates of age-dependent sensitivity and transition probability are of great value to policy-makers regarding the initial age for colorectal cancer screening exams. We found that the mean sojourn time for males is much longer than that for females, which may imply that FOBT screening for colorectal cancer may be more effective for males than for females.

Cochrane systematic review of colorectal cancer screening using the fecal occult blood test (hemoccult): an update

BACKGROUND AND AIMS

Reducing mortality from colorectal cancer (CRC) may be achieved by the introduction of population-based screening programs. The aim of the systematic review was to update previous research to determine whether screening for CRC using the fecal occult blood test (FOBT) reduces CRC mortality and to consider the benefits, harms, and potential consequences of screening.

METHODS

We searched eight electronic databases (Cochrane Library, MEDLINE, EMBASE, CINAHL, PsychINFO, AMED, SIGLE, and HMIC). We identified nine articles describing four randomized controlled trials (RCTs) involving over 320,000 participants with follow-up ranging from 8 to 18 yr. The primary analyses used intention to screen and a secondary analysis adjusted for nonattendance. We calculated the relative risks and risk differences for each trial, and then overall, using fixed and random effects models.

RESULTS

Combined results from the four eligible RCTs indicated that screening had a 16% reduction in the relative risk (RR) of CRC mortality (RR 0.84, 95% confidence interval [CI] 0.78-0.90). There was a 15% RR reduction (RR 0.85, 95% CI 0.78-0.92) in CRC mortality for studies that used biennial screening. When adjusted for screening attendance in the individual studies, there was a 25% RR reduction (RR 0.75, 95% CI 0.66-0.84) for those attending at least one round of screening using the FOBT. There was no difference in all-cause mortality (RR 1.00, 95% CI 0.99-1.02) or all-cause mortality excluding CRC (RR 1.01, 95% CI 1.00-1.03).

CONCLUSIONS

The present review includes seven new publications and unpublished data concerning CRC screening using FOBT. This review confirms previous research demonstrating that FOBT screening reduces the risk of CRC mortality. The results also indicate that there is no difference in all-cause mortality between the screened and nonscreened populations.

Pathophysiology, clinical presentation, and management of colon cancer

Colon cancer is believed to arise from two types of precursor polyps via two distinct pathways: conventional adenomas by the conventional adenoma-to-carcinoma sequence and serrated adenomas according to the serrated adenoma-to-carcinoma theory. Conventional adenomas arise from mutation of the APC gene; progression to colon cancer is a multistep process. The fundamental genetic defect in serrated adenomas is unknown. Environmental factors can increase the risk for colon cancer. Advanced colon cancer often presents with symptoms, but early colon cancer and premalignant adenomatous polyps commonly are asymptomatic, rendering them difficult to detect and providing the rationale for mass screening of adults over age 50.

Reducing the incidence and mortality of colon cancer: mass screening and colonoscopic polypectomy

Most colon cancers arise from conventional adenomatous polyps (conventional adenoma-to-carcinoma sequence), while some colon cancers appear to arise from the recently recognized serrated adenomatous polyp (serrated adenoma-to-carcinoma theory). Because conventional adenomas and serrated adenomas are usually asymptomatic, mass screening of asymptomatic patients has become the cornerstone for detecting and eliminating these precursor lesions to reduce the risk of colon cancer. Colonoscopy has become the primary screening test because of its high sensitivity and specificity, and the ability to perform polypectomy. Other screening tests include guaiac tests or fecal immunochemical tests (FIT) for fecal occult blood, and flexible sigmoidoscopy. A minimal colonoscopic withdrawal time of 6 minutes is important to maximize polyp detection at colonoscopy. Chromoendoscopy is an experimental technique used to highlight abnormal colonic areas to identify neoplastic tissue and to potentially determine the histology of colonic polyps at colonoscopy based on superficial pit anatomy.

Sensitivity of latex agglutination faecal occult blood test in the Florence District population-based colorectal cancer screening programme

We evaluated the sensitivity for colorectal cancer (CRC) of the latex agglutination test (LAT), an immunochemical test routinely used in the Florence District screening programme since 2000. Sensitivity was calculated by the proportional interval cancer incidence method in a population of 27,503 consecutive subjects screened in 2000-2002, interval cancers being identified by linkage to the Tuscany Cancer Registry files. Sensitivity was calculated overall and by gender, age, time since last negative LAT, CRC site, and rank of screening. Overall 1- and 2-year sensitivity estimates were 80.7 and 71.5%, respectively, suggesting that faecal occult blood testing screening sensitivity may be suboptimal due to testing or programme quality problems. Increasing screening sensitivity might be achieved if the detection rate of advanced adenomas could be increased without unacceptable loss in specificity.

Screening for colorectal cancer using the faecal occult blood test, Hemoccult

BACKGROUND

Colorectal cancer is a leading cause of morbidity and mortality, especially in the Western world. The human and financial costs of this disease have prompted considerable research efforts to evaluate the ability of screening tests to detect the cancer at an early curable stage. Tests that have been considered for population screening include variants of the faecal occult blood test, flexible sigmoidoscopy and colonoscopy. Reducing mortality from colorectal cancer (CRC) may be achieved by the introduction of population-based screening programmes.

OBJECTIVES

To determine whether screening for colorectal cancer using the faecal occult blood test (guaiac or immunochemical) reduces colorectal cancer mortality and to consider the benefits, harms and potential consequences of screening.

SEARCH STRATEGY

Published and unpublished data for this review were identified by: Reviewing studies included in the previous Cochrane review; Searching several electronic databases (Cochrane Library, Medline, Embase, CINAHL, PsychInfo, Amed, SIGLE, HMIC); and Writing to the principal investigators of potentially eligible trials.

SELECTION CRITERIA

We included in this review all randomised trials of screening for colorectal cancer that compared faecal occult blood test (guaiac or immunochemical) on more than one occasion with no screening and reported colorectal cancer mortality.

DATA COLLECTION AND ANALYSIS

Data from the eligible trials were independently extracted by two reviewers. The primary data analysis was performed using the group participants were originally randomised to ('intention to screen'), whether or not they attended screening; a secondary analysis adjusted for non-attendence. We calculated the relative risks and risk differences for each trial, and then overall, using fixed and random effects models (including testing for heterogeneity of effects). We identified nine articles concerning four randomised controlled trials and two controlled trials involving over 320,000 participants with follow-up ranging from 8 to 18 years.

MAIN RESULTS

Combined results from the 4 eligible randomised controlled trials shows that participants allocated to screening had a 16% reduction in the relative risk of colorectal cancer mortality (RR 0.84, CI: 0.78-0.90). In the 3 studies that used biennial screening (Funen, Minnesota, Nottingham) there was a 15% relative risk reduction (RR 0.85, CI: 0.78-0.92) in colorectal cancer mortality. When adjusted for screening attendance in the individual studies, there was a 25% relative risk reduction (RR 0.75, CI: 0.66 - 0.84) for those attending at least one round of screening using the faecal occult blood test.

AUTHORS' CONCLUSIONS

Benefits of screening include a modest reduction in colorectal cancer mortality, a possible reduction in cancer incidence through the detection and removal of colorectal adenomas, and potentially, the less invasive surgery that earlier treatment of colorectal cancers may involve. Harmful effects of screening include the psycho-social consequences of receiving a false-positive result, the potentially significant complications of colonoscopy or a false-negative result, the possibility of overdiagnosis (leading to unnecessary investigations or treatment) and the complications associated with treatment.

Review in depth and meta-analysis of controlled trials on colorectal cancer screening by faecal occult blood test

BACKGROUND

Several randomized studies have shown that colorectal cancer (CRC) screening by faecal occult blood test (FOBT) reduces CRC mortality. These trials have different designs, especially concerning FOBT frequency and duration, as well as the length of follow-up after stopping FOBT campaigns.

AIMS

To review the effectiveness of screening for CRC with FOBT, to consider the reduction in mortality during or after screening or to identify factors associated with a significant mortality reduction.

METHODS

A systematic review of trials of FOBT screening with a meta-analysis of four controlled trials selected for their biennial and population-based design. The main outcome measurements were mortality relative risk (RR) and 95% confidence interval (CI) of biennial FOBT during short (10 years, i.e. five or six rounds) or long-term (six or more rounds) screening periods, as well as after stopping screening and follow-up during 5-7 years. The meta-analysis used the Mantel-Haenszel method with fixed effects when the heterogeneity test was not significant, and used 'intent to screen' results.

RESULTS

Although the quality of the four trials was high, only three were randomized, and one used rehydrated biennial FOBT associated with a high colonoscopy rate (28%). A meta-analysis of mortality results showed that subjects allocated to screening had a reduction of CRC mortality during a 10-year period (RR 0.86; CI 0.79-0.94) although CRC mortality was not decreased during the 5-7 years after the 10-year (six rounds) screening period, nor in the last phase (8-16 years after the onset of screening) of a long-term (16 years or nine rounds) biennial screening. Whatever the design of the period of ongoing FOBT, CRC incidence neither decreased nor increased, although it was reduced for 5-7 years after the 10-year screening period. Neither the design nor the clinical or demographic parameters of these trials were independently associated with CRC mortality reduction.

CONCLUSION

Biennial FOBT decreased CRC mortality by 14% when performed over 10 years, without evidence-based benefit on CRC mortality when performed over a longer period. No independent predictors of CRC mortality reduction have been identified in order to allow a CRC screening programme in any subgroups of subjects at risk.

Screening for colorectal cancer--now and the near future

When used appropriately, screening for colorectal cancer (CRC) can reduce disease-related morbidity and mortality. Current methods include fecal occult blood testing (FOBT), flexible sigmoidoscopy [FS], barium enema, and colonoscopy; all are cost-effective techniques. Unfortunately, offering an array of options has not increased screening utilization, which continues to lag behind that of other common cancers. Newer techniques, particularly virtual colonoscopy (VC) and stool DNA testing, may offer attractive alternatives for healthcare provider recommendation and patient use.

From Colonic Polyps to Colon Cancer: Pathophysiology, Clinical Presentation, and Diagnosis

Epidemiologists, basic researchers, clinicians, and public health administrators unite! Develop and implement a simple, safe, and effective preventive and screening test for colon cancer. The public will willingly and enthusiastically accept such a test. Many thousands of lives are at stake every year.

The pathophysiology, clinical presentation, and diagnosis of colon cancer and adenomatous polyps

A review of the pathophysiology, clinical presentation, and diagnosis of colon cancer and colonic polyps is important and timely. This field is rapidly changing because of breakthroughs in the molecular basis of carcinogenesis and in the technology for colon cancer detection and treatment. This article reviews colon cancer and colonic polyps, with a focus on recent dramatic advances, to help the pri-mary care physician and internist appropriately refer patients for screening colonoscopy and intelligently evaluate colonoscopic findings to reduce the mortality from this cancer.

Screening of patients at average risk for colon cancer

Both the incidence and the mortality from colorectal cancer can be substantially reduced by primary and secondary prevention. There are many screening tests for colorectal cancer, and any test should result in a reduction in colorectal cancer incidence and mortality. If the age-eligible population undergoes these screening tests, the burden of colorectal cancer should be substantially reduced. The scientific evidence related to secondary prevention, specifically screening of individuals at average risk for colorectal cancer, is presently reviewed.

Fecal occult blood screening--trial evidence, practice and beyond

Colorectal cancer is a leading cause of morbidity and mortality in Western countries. Primary prevention and early detection of this malignancy has been shown in multiple research set-ups, and using different modalities, to be effective in reducing the incidence and mortality rates of this disease. Three randomized controlled trials have been conducted over the last 30 years to evaluate the efficacy of periodic screening with fecal occult blood tests (FOBT). These studies have consistently demonstrated mortality reduction with biennial as well as annual testing after 8-18 years of follow-up. A significant primary prevention effect through reduction of colorectal cancer incidence was also reported. The results of the Israeli population-based screening program using Hemoccult Sensa show that it is possible to achieve a high detection rate in a well-organized community set-up and, in addition, also a shift in tumor stage towards smaller tumors, a low positivity rate, and an acceptable false positivity rate. FOBT is cheap and performs very well in cost effectiveness analyses evaluating the cost of detecting one cancer. This is quite a rare situation where mortality reduction can be achieved with a simple rather than a sophisticated technology. Research to further enhance the cancer detection capabilities of FOBT through the incorporation of molecular testing of the stool for tumor genes is underway. Multiple policymakers are already recommending this procedure for routine screening of average risk population. Taking their recommendations into action is of major importance.

Sensitivity and specificity of a stool DNA multitarget assay panel for the detection of advanced colorectal neoplasia

Colorectal cancer is the second-leading cause of cancer death. New noninvasive options for screening capable of diagnosing cancer at an early stage are needed to improve compliance and reduce mortality. This study was designed to provide an estimate of the sensitivity and specificity of a multitarget assay panel (MTAP) of stool DNA changes. Eighty patients with advanced colorectal neoplasia and 212 control subjects provided stool samples before colonoscopy. Patients with hereditary colorectal cancer syndromes were excluded. The MTAP included 21 specific mutations in the adenomatous polyposis coli (APC), p53, and K-ras genes, a microsatellite instability marker (BAT-26), and a marker of abnormal apoptosis (DNA Integrity Assay). All samples were analyzed in the clinical laboratory at EXACT Sciences. Multitarget assay panel detected 33 of 52 patients (63.5%, 95% confidence interval [CI], 49.0%-76.4%) with invasive colorectal cancer, including 26 of 36 (72.2%) with node-negative disease (American Joint Committee on Cancer [AJCC] stage I/II) and 7 of 16 (43.7%) with advanced disease (AJCC stage III/IV). Sixteen of 28 patients (57.1%; 95% CI, 37.2%-75.5%) with advanced adenomas (lesions containing high-grade dysplasia, villous adenomas, or tubular adenomas > 1 cm in size) were detected, including 6 of 7 (85.7%) with high-grade dysplasia and 10 of 21 (47.6%) with other advanced adenomas. Specificity was 96.2% (95% CI, 92.7%-98.4%) in patients with either no colorectal lesions or diminutive polyps. Multitarget assay panel has better sensitivity than that reported with use of Hemoccult(R) II in fecal occult blood testing, with similar specificity. Sensitivity appeared to be equally high for patients with node-negative and advanced disease, as well as for advanced adenomas. This study contained a disproportionately high number of distal cancers and, as such, may not be representative of results in proximal lesions. Although a prospective study in an average-risk population is needed to validate these findings, MTAP may offer an important noninvasive option for population-based screening.

Colorectal cancer screening: scientific review

CONTEXT

Screening for colorectal cancer clearly reduces colorectal cancer mortality, yet many eligible adults remain unscreened. Several screening tests are available, and various professional organizations have differing recommendations on which screening test to use. Clinicians are challenged to ensure that eligible patients undergo colorectal cancer screening and to guide patients in choosing what tests to receive.

OBJECTIVE

To critically assess the evidence for use of the available colorectal cancer screening tests, including fecal occult blood tests, sigmoidoscopy, colonoscopy, double-contrast barium enema, and newer tests, such as virtual colonoscopy and stool-based molecular screening.

DATA SOURCES

All relevant English-language articles were identified using PubMed (January 1966-August 2002), published meta-analyses, reference lists of key articles, and expert consultation.

DATA EXTRACTION

Studies that evaluated colorectal cancer screening in healthy individuals and assessed clinical outcomes were included. Evidence from randomized controlled trials was considered to be of highest quality, followed by observational evidence. Diagnostic accuracy studies were evaluated when randomized controlled trials and observational studies were not available or did not provide adequate evidence. Studies were excluded if they did not evaluate colorectal screening tests and if they did not evaluate average-risk individuals.

DATA SYNTHESIS

Randomized controlled trials have shown that fecal occult blood testing can reduce colorectal cancer incidence and mortality. Case-control studies have shown that sigmoidoscopy is associated with a reduction in mortality, and observational studies suggest colonoscopy is effective as well. Combining fecal occult blood testing and sigmoidoscopy may decrease mortality and can increase diagnostic yield.

CONCLUSION

The recommendation that all men and women aged 50 years or older undergo screening for colorectal cancer is supported by a large body of direct and indirect evidence. At present, the available evidence does not currently support choosing one test over another.

Hereditary colorectal cancer: screening and management

Colorectal cancer (CRC) affects approximately 6% of the US population, with equal distribution between men and women. It is hereditary in a high proportion of cases and is one of the most preventable cancers. Detection and removal of its precursor lesions, the adenomatous polyps, is the foundation of preventive strategies. However, once CRC is diagnosed, surgical resection is the only cure. The likelihood of cure is higher when CRC is diagnosed at an early stage. Dietary and lifestyle modifications have little, if any, impact on CRC. Endoscopy with polypectomy prevents cancer deaths. The most important issues are screening and surveillance by any of the recommended modalities. Remaining concerns include the choice of screening tests, optimal testing intervals, and cost effectiveness. Patients may be stratified by personal and family risk and by the specific strategies used. Newer developments in genetic testing and imaging, including virtual colonoscopy, hold promise for future prevention. Chemoprevention with nonsteroidal anti-inflammatory drugs may have a role in high-risk populations. Colonoscopy is the most effective method of CRC prevention.

Colorectal cancer screening

During the past decade we have seen dramatic advances in colon cancer screening. Reduction in mortality in average risk screening for colorectal cancer has now been shown in multiple trials. Efforts to increase public awareness and compliance with evidence-based screening guidelines are underway. Recent guidelines have incorporated family history, as it has been identified as a common risk factor. The genes responsible for the inherited syndromes of colon cancer have been identified and genetic testing is available. Currently, screening the average risk population over the age of 50 would reduce mortality from colon cancer by 50%. Future advances will likely include improved screening tests, and the development of familial genetic testing.

Secondary prevention: screening and surveillance of persons at average and high risk for colorectal cancer

Secondary prevention of colorectal cancer with FOBT and endoscopy with polypectomy decreases cancer deaths. Other available modalities include genetic tests and imaging studies, but outcomes data are not yet available. Issues remain concerning the most appropriate test, the optimal intervals, and cost-efficacy. Patients may be stratified by personal and family risk, and specific strategies may be used. Newer developments in genetic tests and imaging, including virtual colonoscopy, hold promise for the future. The most important issue at present is to have people screened or surveilled by any of the recommended modalities.

Single flexible sigmoidoscopy screening to prevent colorectal cancer: baseline findings of a UK multicentre randomised trial

BACKGROUND

This randomised controlled trial is examining the hypothesis that a single flexible sigmoidoscopy screening offered at around age 60 years can lower the incidence and mortality of colorectal cancer. We report here on acceptability, safety, feasibility, and yield.

METHODS

Men and women aged 55-64 years, in 14 UK centres, who responded to a mailed questionnaire that they would attend for flexible sigmoidoscopy screening if invited, were randomly assigned screening or control (ratio one to two). The control group was not contacted. Small polyps were removed during screening, and colonoscopy was undertaken if high-risk polyps (three or more adenomas, size 1 cm or greater, villous, severely dysplastic, or malignant) were found.

FINDINGS

Of 354,262 people asked about their interest in having flexible sigmoidoscopy screening, 194,726 (55%) responded positively, and 170,432 eligible individuals were randomised. Attendance among those assigned screening was 71% (40,674 of 57,254). 2131 (5%) were classified as high-risk and referred for colonoscopy; 38,525 with no polyps or only low-risk polyps detected were discharged. Distal adenomas were detected in 4931 (12.1%) and distal cancer in 131 (0.3%). Proximal adenomas were detected in 386 (18.8% of those undergoing colonoscopy) and proximal cancer in nine cases (0.4%). 62% of cancers were Dukes' stage A or locally excised. There was one perforation after flexible sigmoidoscopy and four after colonoscopy. An average of 48 people were screened, and two or three colonoscopy referrals generated, per centre each week. Interpretation Our flexible sigmoidoscopy screening regimen is acceptable, feasible, and safe. The prevalence of neoplasia is high, and colonoscopy referral rates of 5% are acceptable.

Fecal occult blood test screening for colorectal cancer

In summary, high-quality scientific studies indicate that the use of the FOBT for colorectal cancer screening has a number of important advantages. The test is capable of detecting most early colorectal cancers and many advanced adenomas. It has been shown in randomized, controlled trials to reduce substantially colorectal cancer mortality and incidence. The FOBT is feasible, widely available, and acceptable to most individuals. It has a low up-front cost and is highly cost-effective. Combining annual FOBT with periodic flexible sigmoidoscopy seems to be an especially effective screening option. Limitations of FOBT screening include its low sensitivity for polyps, especially smaller ones. Some of the trials report a relatively low sensitivity for detecting cancers located in the distal colon. The test has a relatively low specificity, so there are many false-positive screens; and for it to be most effective, repetitive screening is necessary. Balancing these advantages and disadvantages, the evidence-based screening guidelines have concluded that FOBT screening has a major role to play in colorectal cancer control and a program of annual FOBT plus flexible sigmoidoscopy every 5 years is a preferred option for screening the asymptomatic, average-risk population for colorectal cancer. Short of doing direct colonoscopy screening for the entire at-risk population, the FOBT currently is the best available method of identifying asymptomatic, average-risk people most likely to benefit from colonoscopy.

Fecal occult blood screening for colorectal cancer: open issues

Data from seven case-control and--mainly--three randomized clinical trials consistently indicate that biennial fecal occult blood screening (FOBT) can reduce colorectal cancer (CRC) mortality by approximately 20% after 10-18 years. The reduction may be greater in compliant subjects. In the long-term, incidence also appears to be reduced. There are suggestions that the effect of annual screening may be greater, although data are inadequate to quantify the potential advantages of annual versus biennial screening. The issue of the effectiveness of FOBT in the general population and, more important, of comparative cost-effectiveness with other possible screening tests for CRC, however, remain open to discussion.

Colorectal cancer screening

Colorectal cancer causes significant morbidity and mortality in the United States. The incidence of colorectal cancer increases at age 50, approximately. Risk factors that have been identified include a personal history of colorectal cancer or adenomas, a family history of colon cancer or adenomas, inherited colorectal cancer syndromes, and long standing inflammatory bowel disease. Several screening tests have been developed for colorectal cancer prevention. Surveillance strategy is based on an individual's colorectal cancer risk. This article reviews fecal occult blood testing, flexible sigmoidoscopy, colonoscopy, barium enema, and genetic testing.

The effect of fecal occult-blood screening on the incidence of colorectal cancer

BACKGROUND

Both annual testing for fecal occult blood and biennial testing significantly reduce mortality from colorectal cancer. However, the effect of screening on the incidence of colorectal cancer remains uncertain, despite the diagnosis and removal of precancerous lesions in many persons who undergo screening.

METHODS

We followed the participants in the Minnesota Colon Cancer Control Study for 18 years. A total of 46,551 people, most of whom were 50 to 80 years old, were enrolled between 1975 and 1978 and randomly assigned to annual screening, biennial screening, or usual care (the control group). Those assigned to the screening groups were asked to prepare and submit two samples from each of three consecutive stools for guaiac-based testing. Those with at least one positive slide in the set of six were offered a diagnostic examination that included colonoscopy. Screening was conducted between 1976 and 1982 and again between 1986 and 1992. Study participants have been followed with respect to newly diagnosed cases of colorectal cancer and deaths. Follow-up has been more than 90 percent complete.

RESULTS

During the 18-year follow-up period, we identified 1359 new cases of colorectal cancer: 417 in the annual-screening group, 435 in the biennial-screening group, and 507 in the control group. The cumulative incidence ratios for colorectal cancer in the screening groups as compared with the control group were 0.80 (95 percent confidence interval, 0.70 to 0.90) and 0.83 (95 percent confidence interval, 0.73 to 0.94) for the annual-screening and biennial-screening groups, respectively. For both screening groups, the number of positive slides was associated with the positive predictive value both for colorectal cancer and for adenomatous polyps at least 1 cm in diameter.

CONCLUSIONS

The use of either annual or biennial fecal occult-blood testing significantly reduces the incidence of colorectal cancer.

Colorectal cancer update. Prevention, screening, treatment, and surveillance for high-risk groups

Great advances have been made in understanding the cause and molecular genesis of colorectal cancer. The disease can be prevented by a healthful diet and lifestyle or by resecting the precursor of most of these cancers, the advanced adenomatous polyp. Screening the average-risk population plus special surveillance for high-risk groups now is recommended by evidence-based guidelines. Surgery is highly curative for patients without distant metastases, and adjuvant therapy improves survival in selected patients with advanced cancers.