Occult Blood Screening Research Articles

The impact of colorectal cancer screening on life expectancy

Methods: The purpose of this study was to assess the effect of screening for colorectal cancer on life expectancy and estimate the number of colonoscopies needed per life year saved. The declining exponential approximation of life expectancy was used to calculate the effect of colorectal cancer screening on expected remaining lifetime. The annual number of deaths from colorectal cancer and the size of the population were obtained from the vital statistics of the United States. Published reports were consulted to determine the decrease in mortality from colorectal cancer achieved by fecal occult blood testing, screening sigmoidoscopy or colonoscopy. A Markov chain analysis was used to determine the endoscopic resources required to screen and survey the entire population of U.S. residents age 50 years until death or age 85 years. Results: Colorectal cancer decreases the life expectancy of U.S. residents aged 50 to 54 years by 292 days and those aged 70 to 74 years by 70 days. Screening with fecal occult blood tests extends expected lifetime of the 2 age groups by 51 and 12 days, respectively, whereas screening with sigmoidoscopy leads to increases of 86 and 21 days. Colonoscopic screening increases expected lifetime by 170 and 41 days, respectively. The number of colonoscopies needed to save 1 year of expected life ranges from 2.9 to 6.0, depending on the type of screening regimen used. Conclusions: The extension of life through screening colonoscopy is two or three times longer than the extension achieved through flexible sigmoidoscopy or fecal occult blood test, respectively. Although a large number of colonoscopies are required to screen the U.S. population, relatively few colonoscopies need to be invested per year of life expectancy saved. (Gastrointest Endosc 2000;51:517-23.)

Relationship between anal occult blood and hepatobiliary pancreatic carcinoma screening.

Cotton swab anal smear instead of stool occult blood test can not only be used as a mass screening method for colorectal cancer, but is an auxiliary way to screen hepatobiliary pancreatic carcinoma. Two hundred and twenty-three cases of hepatobiliary pancreatic carcinoma patients received anal occult blood test, of which 121 were positive (54.3%). The screening test was performed in 14,645 healthy people aged 40-60 years; 511 persons (3.4%) were positive for anal blood. Among these, six cases of digestive tract cancer were found (one oesophageal carcinoma, one gastric cardia carcinoma, two gastric carcinomas, two liver carcinomas). This suggests that when anal occult blood is positive, the patient should be scanned by ultrasonic means to rule out hepatobiliary pancreatic tumour.

A cost-effective analysis of the optimum number of stool specimens collected for immunochemical occult blood screening for colorectal cancer

This study was carried out to assess, from the viewpoint of cost-effectiveness, the optimum number of faecal specimens to collect for use in immunochemical occult blood testing as a means of screening for colorectal cancer. 3300 asymptomatic individuals were subjects of this study. They gave samples for an immunochemical faecal occult blood test, monohaem and colonoscopy was carried out during a medical check-up. For evaluation of the optimum number of sampling specimens, the results of the first day of sampling, those of the first and second days, and those of samples taken for 3 consecutive days were considered as the single-day method, the 2-day method and the 3-day method respectively. The average cost to detect 1 patient with colorectal cancer, the detection rate and the false-positive rate of these three faecal sample collection methods were evaluated. The average costs for one cancer case detected were calculated as $3630.68 for the single-day method, $3350.65 for the 2-day method and $4136.36 for the 3-day method, respectively. The detection rate and the false-positive rate were calculated as 47 and 3.5% for the single-day method, 82 and 4.7% for the 2-day method and 88 and 5.3% for the 3-day method, respectively. This detection rate was significantly different between the single- and the 2-day methods, as well as between the single- and the 3-day methods ( P<0.05). No significant differences in the false-positive rate amongst the three testing methods were observed. This analysis suggests that a 2-day faecal collection method is recommended for immunochemical occult blood screening by Monohaem from the aspects of cost-effectiveness and diagnostic accuracy.

Fecal Occult Blood Screening Reduces Colorectal Cancer Incidence

Fecal occult blood testing has been shown to reduce mortality from colorectal cancer, but does it have an effect on the incidence of colorectal cancer? To find out, researchers followed 46,551 participants of The Minnesota …

Survival of patients with colorectal cancer detected by a community screening program.

To determine survival rates for people with colorectal cancer detected through Bowelscan, a community screening program. Survey of data from local medical practitioners, and comparison with data from State cancer registries. 249 people with colorectal cancer detected after faecal occult blood screening in north-eastern New South Wales, 1987-1996. Follow-up was in 1998-1999. Five-year survival rates and relative survival ratios. Five-year survival rates for the screen-detected cancer patients were 90% for those with Dukes' stage A cancers, 75% for Dukes' B, 52% for Dukes' C and 0 for Dukes' D (although one person with Dukes' D cancer was living at four-year follow-up at the end of the study). Because of the higher percentage of Dukes' A cases in the population whose cancer was detected through screening, the resulting five-year relative survival ratio was significantly better than for those recorded by New South Wales, South Australian and Queensland cancer registries: 0.82 (95% confidence interval, 0.74-0.90) compared to 0.59 (P < or = 0.001). The study supports the findings of three overseas randomised trials that screening reduces mortality from colorectal cancer. We estimate that screening 200,000 people would detect about 250 colorectal cancers and prevent as many as 55 deaths.

Early detection for colorectal cancer: new aspects in fecal occult blood screening.

The authors report on promising diagnostic methods of occult intestinal bleeding and discusses the potential new strategy of early detection of colorectal carcinomas in respect to old and new diagnostic measures available. Because of the limited sensitivity and specificity of classical methods used for the demonstration of occult fecal blood, the authors recommend the introduction of new techniques and markers in screening practice. It is presumed that new discoveries in molecular biology will improve the accuracy of early colorectal cancer prevention. Their implementation into routine screening, however, will not take place in the near future. Until their realization, improved screening efficacy is expected from the use of more specific and sensitive blood tests.

Detection of colorectal neoplasms by the highly sensitive hemoglobin-haptoglobin complex in feces

Screening for fecal occult blood by means of guaiac tests has an unsatisfactory sensitivity for the detection of colorectal neoplasms. The immunological determination of human hemoglobin in feces has a higher sensitivity and specificity, but hemoglobin is degraded during its transport through the gastrointestinal tract. We compared the hemoglobin test to a newly developed immuno-chemiluminometric (ILMA) assay for quantifying the hemoglobin-haptoglobin complex in feces which shows high stability against degradation. From each of 621 patients with gastrointestinal complaints before scheduled colonoscopy we collected two 1-ml samples from a single stool; there were no dietary restrictions. The sensitivity for detecting colorectal carcinomas proved 87% with hemoglobin. With the hemoglobin-haptoglobin complex it was 87% at a cutoff level of 1.5 microg/g feces, 83% at 2.0 microg/g feces, and 78% at 2.5 and 3.0 microg/g feces. The sensitivity for detecting large adenomatous polyps was 54% with hemoglobin, 76% with the hemoglobin-haptoglobin complex at a cutoff point of 1.5 microg/g feces, 73% with the hemoglobin-haptoglobin complex at 2.0 and 2.5 microg/g feces, and 65% with the hemoglobin-haptoglobin complex at 3.0 microg/g feces. The optimal cutoff point for the hemoglobin-haptoglobin complex was estimated to be 2.0 microg/g stool. The specificity for hemoglobin (99%) was significantly higher than that for the hemoglobin-haptoglobin complex at 2.0 microg/g feces (96%). Immunological determination of the hemoglobin-haptoglobin complex in feces has a comparable sensitivity as the fecal hemoglobin assay for colorectal carcinomas and a significantly higher sensitivity for adenomatous polyps but a significantly lower specificity. Its use for colorectal cancer prevention is currently being evaluated in a screening study.

Cost-effectiveness of faecal occult blood screening for colorectal cancer: results of the Nottingham trial

Cost-effectiveness of faecal occult blood screening for colorectal cancer: results of the Nottingham trial

Diagnostic testing following fecal occult blood screening in the elderly.

Screening with a fecal occult blood test (FOBT) has been shown to reduce colorectal cancer mortality in controlled trials. Recently, Medicare approved payment for FOBT screening. We evaluated the pattern of diagnostic testing following the initial FOBT in elderly Medicare beneficiaries. Such follow-up testing would in the long run influence both the cost and the benefit of widespread use of FOBT. Using Medicare's National Claims History System, we identified 24 246 Americans 65 years old or older who received FOBT at physician visits between January 1 and April 30, 1995. Prior to FOBT, these people had no evidence of any conditions for which FOBT might be used diagnostically. We examined relevant diagnostic testing in this cohort during the subsequent 8 months and determined what proportion of those received an evaluation recommended by the American College of Physicians. For every 1000 Medicare beneficiaries who received FOBT, 93 (95% confidence interval = 89-96 per 1000) had positive findings and relevant testing in the subsequent 8 months. Of these, 34% had the recommended evaluation of either colonoscopy or flexible sigmoidoscopy with an air-contrast barium enema. Another 34% received a partial colonic evaluation with either flexible sigmoidoscopy or a barium enema. The remaining 32% received other gastrointestinal (GI) testing without evaluation of the colonic lumen: computed tomography or magnetic resonance imaging of the abdomen (15%), upper GI series (10%), carcinoembryonic antigen (7%), and upper endoscopy (2%). Restricting the analysis to testing performed within 2 months of the initial FOBT yielded similar results. Following FOBT, many Medicare beneficiaries get further diagnostic testing, but only a small proportion receives the recommended evaluation. With this pattern of practice, population screening is likely to be more costly and less effective than estimated from controlled trials.

The risks of screening: data from the Nottingham randomised controlled trial of faecal occult blood screening for colorectal cancer

AIMSTo determine the harm that ensues from faecal occult blood (FOB) screening for colorectal cancer.METHODS150 251 people were randomly allocated either to receive biennial Haemoccult FOB tests (n =75 253)...

Colorectal cancer mortality: effectiveness of biennial screening for fecal occult blood.

In 1993, a randomized controlled trial in Minnesota showed, after 13 years of follow-up, that annual fecal occult blood testing was effective in reducing colorectal cancer mortality by at least 33%. Biennial screening (i.e., every 2 years) resulted in only a 6% mortality reduction. Two European trials (in England and in Denmark) subsequently showed statistically significant 15% and 18% mortality reductions with biennial screening. Herein, we provide updated results-through 18 years of follow-up--from the Minnesota trial that address the apparent inconsistent findings among the trials regarding biennial screening. From 1976 through 1977, a total of 46551 study subjects, aged 50-80 years, were recruited and randomly assigned to an annual screen, a biennial screen, or a control group. A screen consisted of six guaiac-impregnated fecal occult blood tests (Hemoccult) prepared in pairs from each of three consecutive fecal samples. Participants with at least one of the six tests that were positive were invited for a diagnostic examination that included colonoscopy. All participants were followed annually to ascertain incident colorectal cancers and deaths. The numbers of deaths from all causes were similar among the three study groups. Cumulative 18-year colorectal cancer mortality was 33% lower in the annual group than in the control group (rate ratio, 0.67; 95% confidence interval [CI] = 0.51-0.83). The biennial group had a 21% lower colorectal cancer mortality rate than the control group (rate ratio, 0.79; 95% CI = 0.62-0.97). A marked reduction was also noted in the incidence of Dukes' stage D cancers in both screened groups in comparison with the control group. The results from this study, together with the other two published randomized trials of fecal occult blood screening, are consistent in demonstrating a substantial, statistically significant reduction in colorectal cancer mortality from biennial screening.

Faecal occult blood screening and reduction of colorectal cancer mortality: a case-control study.

To estimate the efficacy of screening on colorectal cancer mortality, a population-based case–control study was conducted in well-defined areas of Burgundy (France). Screening by faecal occult blood test prior to diagnosis in cases born between 1914 and 1943 and who died of colorectal cancer diagnosed in 1988–94 was compared with screening in controls matched with the case for age, sex and place of residence. Cases were less likely to have been screened than controls, with an odds ratio (OR) of 0.67 [95% confidence interval (CI) 0.48–0.94]. The negative overall association did not differ by gender or by anatomical location. The odds ratio of death from colorectal cancer was 0.64 (95% CI 0.46–0.91) for those screened within 3 years of case diagnosis compared with those not screened. It was 1.14 (95% CI 0.50–2.63) for those screened more than 3 years before case diagnosis. There was a negative association between the risk of death from colorectal cancer and the number of participations in the screening campaigns. The inverse association between screening for faecal occult blood and fatal colorectal cancer suggests that screening can reduce colorectal cancer mortality. This report further supports recommendations for population-based mass screening with faecal occult blood test. © 1999 Cancer Research Campaign

Screening guidelines for colorectal cancer

Evidence-based guidelines recommend that all asymptomatic, average-risk U.S. citizens >50 years of age be encouraged to undergo screening for colorectal cancer. Those at higher risk should be offered more intensive screening and follow-up surveillance. It is estimated that widespread adoption of these recommendations could reduce mortality from colorectal cancer by >50%. The only screening methods that have been evaluated directly are the fecal occult blood test and flexible sigmoidoscopy. Current guidelines now recommend annual screening for fecal occult blood plus flexible sigmoidoscopy every 5 years for asymptomatic, average-risk men and women >50 years of age. Indirect evidence supports the options of colonoscopy or barium enema x-ray screening for highly motivated individuals, but these methods have not yet been tested in prospective trials. In the future, gene-based screening tests may be developed, and computed tomography of the colon (“virtual colonoscopy”) may prove effective and feasible.

Predictors of fecal occult blood screening among older socioeconomically disadvantaged Americans: a replication study

Socioeconomically disadvantaged elderly are less likely to participate in fecal occult blood testing (FOBT). A quasi-experimental design was used in this operational replication study to determine predictors at baseline of subsequent participation in FOBT. Sixty-five percent of the 211 participants in the replication study participated in FOBT, and 47% of the 171 participants in the original study participated in FOBT. Predictors for FOBT in the replication study were male gender, age of 65–75 years old, ability to go places without assistance, history of having had a digital rectal examination and FOBT. This replication study supports targeting socioeconomically disadvantaged populations for FOBT as well as females, persons 85 years and older, persons who need assistance in travel, and persons who have not had FOBT before. The results show that socioeconomically disadvantaged persons will participate in FOBT when effective educational interventions that include adaptation for aging changes are used.

Screening for colorectal cancer reduces emergency admissions

Colorectal cancer is common and accounts for over 15,000 deaths annually in England and Wales. Up to 30% of these patients require emergency surgery. Screening for colorectal cancer can reduce the mortality of colorectal cancer. This study addresses the impact of a population-based screening study on emergency admissions with colorectal cancer. From 1981 a randomized trial of Faecal Occult Blood (FOB) screening has been undertaken in the Nottingham area, recruiting over 150,000 patients. The present study examined the records of patients enrolled in this study who presented as an emergency with colorectal cancer. Colorectal cancer was identified in 1962 cases, of which 468 (23.9%) presented as emergencies. The overall compliance was 60% (proportion of individuals completing at least one test). There were significantly fewer emergencies in the Screen-detected group compared with the Control group (P = < 0.0001). This group also had a significantly reduced 30-day mortality and a lower stoma rate than the Control group. Conversely the Non-responders had a significantly greater proportion of emergency admissions and a significantly increased stoma rate compared with the Control group. Screening for colorectal cancer using a faecal occult blood test can significantly reduce the number of emergency presentations with colorectal cancer. It is likely that the introduction of a national programme of screening for colorectal cancer would lead to increased compliance and that this would lead to a significant reduction in the emergency workload on the National Health Service from colorectal cancer.

Faecal occult blood screening for colorectal cancer: is it cost-effective?

Recently published evidence from two large-scale clinical trials conducted in England and in Denmark suggests that faecal occult blood screening for colorectal cancer significantly reduces mortality. However, before screening can be advocated as part of national health policy, its cost-effectiveness must be demonstrated. The English screening trial has been the subject of a detailed economic evaluation over the past 10 years In this paper, cost-effectiveness estimates of screening are presented, based on cost and outcome data combined in a mathematical model developed from the trial's clinical findings The estimates of cost per quality-adjusted life-year gained from colorectal cancer screening show the procedure to be of similar cost-effectiveness to breast cancer screening in the short term. Over the longer term, however, the estimates for colorectal cancer screening appear superior.

Should we be screening for colorectal cancer?

Mass population screening for asymptomatic neoplastic disease is now national policy in the UK for breast cancer and has been established for many years in the early diagnosis of carcinoma of the cervix. Cancer screening is based on the concept that treatment is more effective when the disease is localised and aims to detect it when it is at a less advanced clinico-pathological stage prior to the development of symptoms. Because colorectal cancer develops in benign adenomatous polyps which are often amenable to endoscopic resection, screening may both reduce the incidence of the disease as well as improving outcome from it. Flexible sigmoidoscopy screening focuses mainly on the detection of potentially malignant adenomas, their endoscopic removal producing a decrease in colorectal cancer incidence. It is a promising approach but conclusive data on effectiveness from a Medical Research Council-sponsored multicentre randomised controlled trial will not be available before 2006. Faecal occult blood testing aims to preferentially detect early stage invasive disease. Three randomised controlled trials of faecal occult blood screening show that the disease can be detected earlier in its development leading to reduced mortality from the disease--and that this is achieved at reasonable cost. The Department of Health is currently giving consideration to its national implementation.

OP30. Cost-effectiveness of faecal occult blood screening for colorectal cancer: results of the Nottingham trial

OP30. Cost-effectiveness of faecal occult blood screening for colorectal cancer: results of the Nottingham trial

Fecal occult blood screening in the Minnesota study: role of chance detection of lesions.

In the Minnesota Colon Cancer Control Study, annual fecal occult blood testing reduced mortality from colorectal cancer by at least 33.4%. Some attribute a large part of this reduction to chance detection of cancers by colonoscopies; rehydration of guaiac test slides greatly increased positivity and consequently the number of colonoscopies performed. This study was conducted to determine how much of the reduction resulted from chance detection. We used a mathematical model developed by Lang and Ransohoff to estimate the proportion of the 33.4% mortality attainable by chance alone. Applying the model requires the specification of five parameters: duration of follow-up, rate of compliance with fecal occult blood testing, rate of compliance with colonoscopy, positivity rate, and efficacy of colonoscopy in reducing colorectal cancer mortality. We took values for four of the five parameters directly from the Minnesota study. For the fifth parameter, efficacy of colonoscopy, we selected a value of 60%, based on the conclusions of another study. Whereas the Lang-Ransohoff model selects persons for colonoscopy by chance alone, those with bleeding cancers would also be selected by sensitive fecal occult blood testing. We therefore adjusted the result of the Lang-Ransohoff model for this dual detectability. We found that 16%-25% of the reduction in colorectal cancer deaths effected by fecal occult blood testing in the Minnesota study was due to chance detection; the remainder was due to sensitive detection. Chance played a minor role in the detection of colorectal cancers by fecal occult blood testing in the Minnesota study.

Measuring Effectiveness of Lung Cancer Screening: From Consensus to Controversy and Back

While intense controversy exists regarding screening for breast, colorectal, and prostate cancer, a consensus exists regarding lung cancer screening. All organizations recommend against any efforts to detect early lung cancer because each of four randomized controlled trials (RCTs) has failed to demonstrate a significant reduction in lung cancer mortality as a result of screening. Disease-specific mortality is assumed to represent the best measure of screening effectiveness in RCTs, because it is not subject to confounding by lead time, length, or overdiagnosis biases. However, the effects of these biases are predictable, so accurate assessments of the degree of confounding by these biases can be made. Moreover, the ability of mortality to accurately reflect cancer death rates depends on the ability of randomization to create experimental and control populations that have an equal risk of dying of the disease under study, except insofar as early detection may reduce that risk. Because the majority of participants in screening trials never develop the disease under investigation, small absolute differences in disease risk between groups often persist despite randomization, and such differences translate into much larger proportional differences in the size of subgroups at risk for disease-specific mortality. This effect confounds the ability of disease-specific mortality to accurately measure screening effectiveness. A total of 18 RCTs have been conducted to evaluate screening for breast, colorectal, and lung cancer. In the only two RCTs that reported a significant mortality reduction for screening mammography in breast cancer, and in the one RCT that reported a significant mortality reduction for fecal occult blood screening in colorectal cancer, population differences led mortality comparisons to overestimate the effectiveness of screening. In lung cancer, no significant mortality reductions have been reported (to my knowledge), but in the two RCTs most directly addressing the effectiveness of chest radiograph (CXR) screening, population differences led mortality comparisons to underestimate the ability of CXRs to reduce the risk of dying of lung cancer. Although mortality is believed to be the best measure of outcome, not a single example can be cited as definitive proof of efficacy for any screening strategy. Thus, screening cannot be recommended for any cancer on the basis of consistent reductions in mortality in RCTs. Current policy, which calls for no early detection efforts for lung cancer, implicitly accepts the validity of two contradictory assertions. Conventional wisdom maintains that lung cancer is a highly virulent disease and that metastases are present at inception; accordingly, early detection is ineffective. However, RCTs suggest that lung cancer is an indolent disease and that radiographically detected lesions are clinically unimportant; accordingly, early detection is unnecessary. Such contradictions mandate some rethinking of the fundamental assumptions underlying screening evaluation. Considerable evidence suggests that annual CXR screening could result in a dramatic reduction in lung cancer mortality in our society. However, proper interpretation of the data depends completely on how screening effectiveness is measured. Given the enormous public health importance of this issue, a consensus conference is recommended to determine whether lung cancer screening can save lives.