Screening for colorectal cancer in a high-risk population. Results of a mathematical model

Estimating the Effect of Targeted Screening Strategies: An Application to Colonoscopy and Colorectal Cancer

Supplemental Digital Content is available in the text.

Screening behavior depends on previous screening history and family members’ behaviors, which can act as both confounders and intermediate variables on a causal pathway from screening to disease risk. Conventional analyses that adjust for these variables can lead to incorrect inferences about the causal effect of screening if high-risk individuals are more likely to be screened. Analyzing the data in a manner that treats screening as randomized conditional on covariates allows causal parameters to be estimated; inverse probability weighting based on propensity of exposure scores is one such method considered here. I simulated family data under plausible models for the underlying disease process and for screening behavior to assess the performance of alternative methods of analysis and whether a targeted screening approach based on individuals’ risk factors would lead to a greater reduction in cancer incidence in the population than a uniform screening policy. Simulation results indicate that there can be a substantial underestimation of the effect of screening on subsequent cancer risk when using conventional analysis approaches, which is avoided by using inverse probability weighting. A large case–control study of colonoscopy and colorectal cancer from Germany shows a strong protective effect of screening, but inverse probability weighting makes this effect even stronger. Targeted screening approaches based on either fixed risk factors or family history yield somewhat greater reductions in cancer incidence with fewer screens needed to prevent one cancer than population-wide approaches, but the differences may not be large enough to justify the additional effort required. See video abstract at, http://links.lww.com/EDE/B207.

Colonoscopy findings in high-risk individuals compared to an average-risk control population

BACKGROUND AND AIMS

There is clear evidence of reduced morbidity and mortality from regular colonoscopy programs in patients with Lynch syndrome (LS). Today, also individuals with empirically increased risks of colorectal cancer (CRC) are offered colonoscopic surveillance. The aim was to compare the findings at the first screening colonoscopy in LS carriers, and individuals with an increased risk of bowel cancer due to family history of CRC with a control population.

METHODS

Altogether 1397 individuals with an increased risk for CRC were divided in four risk groups: one with LS carriers and three groups with individuals with different family history of CRC. The findings were compared between the different risk groups and a control group consisting of 745 individuals from a control population who took part in a population-based colonoscopy study.

RESULTS

In LS, 30% of the individuals had adenomas and 10% advanced adenomas. The corresponding figures in the other risk groups were 14-24% and 4-7%, compared with 10% and 3% in the control group. The relative risk of having adenomas and advanced adenomas was, compared to controls, significantly higher for all risk groups except the group with the lowest risk. Age was a strong predictor for adenomas and advanced adenomas in both risk individuals and controls.

CONCLUSIONS

Individuals with a family history of CRC have a high prevalence and cumulative risk of adenomas and advanced adenomas, and screening is motivated also in this risk group.

Modeling the Adenoma and Serrated pathway to Colorectal CAncer (ASCCA)

Several colorectal cancer (CRC) screening models have been developed describing the progression of adenomas to CRC. Currently, there is increasing evidence that serrated lesions can also develop into CRC. It is not clear whether screening tests have the same test characteristics for serrated lesions as for adenomas, but lower sensitivities have been suggested. Models that ignore this type of colorectal lesions may provide overly optimistic predictions of the screen-induced reduction in CRC incidence. To address this issue, we have developed the Adenoma and Serrated pathway to Colorectal CAncer (ASCCA) model that includes the adenoma-carcinoma pathway and the serrated pathway to CRC as well as characteristics of colorectal lesions. The model structure and the calibration procedure are described in detail. Calibration resulted in 19 parameter sets for the adenoma-carcinoma pathway and 13 for the serrated pathway that match the age- and sex-specific adenoma and serrated lesion prevalence in the COlonoscopy versus COlonography Screening (COCOS) trial, Dutch CRC incidence and mortality rates, and a number of other intermediate outcomes concerning characteristics of colorectal lesions. As an example, we simulated outcomes for a biennial fecal immunochemical test screening program and a hypothetical one-time colonoscopy screening program. Inclusion of the serrated pathway influenced the predicted effectiveness of screening when serrated lesions are associated with lower screening test sensitivity or when they are not removed. To our knowledge, this is the first model that explicitly includes the serrated pathway and characteristics of colorectal lesions. It is suitable for the evaluation of the (cost)effectiveness of potential screening strategies for CRC.

Barriers to screening colonoscopy in an urban population: a study to help focus further efforts to attain full compliance

BACKGROUND

Awareness of colorectal cancer and decision for colorectal cancer screening is influenced by multiple factors including ethnicity, level of education, and adherence to regular medical follow up.

OBJECTIVE

Our survey aimed at assessing barriers to colorectal cancer screening among urban population.

DESIGN

This study is a survey of the general population.

SETTING

This study was made at a local community in the downtown area of a metropolitan city.

PATIENTS/SUBJECTS

The study population for this survey included 2000 non-institutionalized residents from local community of Brooklyn downtown area of City of Brooklyn, NY, USA. All participants were 50 years or older.

INTERVENTION

No intervention was done.

MAIN OUTCOME MEASUREMENT

The survey questionnaire collected information about demographic, socioeconomic level, awareness of various cancers and their screening methods, and awareness of screening colonoscopy.

RESULTS

Colonoscopy was identified as the best screening test by 31 % of the subjects. Pain and discomfort was the major reason for not having a colonoscopy. The fear of a complication declined significantly after the first colonoscopy but fear of pain and discomfort increased. Difficulty with bowel preparation before a colonoscopy was a significant problem; it discouraged significant number of participants from having another colonoscopy.

LIMITATION

This study is limited by its small sample size.

CONCLUSION

Physician/family and peer influence seems important but influencing only a minority of subjects. Fear of complications should be allayed using accurate statistical information. Pain should be significantly diminished and/or eliminated during colonoscopy. Future research should focus to minimize complexity and discomfort associated with bowel preparation.

Colorectal cancer screening by double contrast barium enema in Thai people

PURPOSE

The incidence of colorectal cancer (CRC) has been increasing in Asian countries including Thailand. Double contrast barium enema (DCBE) is one of the investigation tools used in CRC screening. This study aimed to determine the incidence of colorectal neoplasm detected at screening by DCBE in Thai people.

METHODS

The computerized radiology database of screening DCBE in Thai adults between June 2009 and October 2011 at the Faculty of Medicine, Siriraj Hospital, was reviewed. DCBE examination performed in a surveillance program after curative CRC resection or the removal of colorectal polyps was also considered as a screening DCBE.

RESULTS

A total of 819 screening DCBEs performed during this 28-month period were analyzed. The mean age of patients was 59.8 ∓ 13.6 years. Of the total, 467 (57%) were male. A family history of CRC and a previous history of curative CRC resection or polyp removal were noted in 34 patients (4%) and 124 patients (15%), respectively. A total of 31 patients (3.8%; 95%CI = 2.7%-5.3%) were reported to have colorectal polyp or mass demonstrated on DCBE. Of these, follow-up endoscopy was performed in 20 cases (65%). According to pathological results, the incidence of advanced adenoma and CRC detected at screening DCBE was 0.7% (95%CI = 0.3%-1.6%; n=6) and 0.4% (95%CI = 0.1%-1.1%; n=3), respectively.

CONCLUSIONS

The screening DCBE performed in Thai adults had a diagnostic yield of 0.7% for advanced adenoma and 0.4% for CRC.

A systematic comparison of microsimulation models of colorectal cancer: the role of assumptions about adenoma progression

BACKGROUND

As the complexity of microsimulation models increases, concerns about model transparency are heightened.

METHODS

The authors conducted model "experiments" to explore the impact of variations in "deep" model parameters using 3 colorectal cancer (CRC) models. All natural history models were calibrated to match observed data on adenoma prevalence and cancer incidence but varied in their underlying specification of the adenocarcinoma process. The authors projected CRC incidence among individuals with an underlying adenoma or preclinical cancer v. those without any underlying condition and examined the impact of removing adenomas. They calculated the percentage of simulated CRC cases arising from adenomas that developed within 10 or 20 years prior to cancer diagnosis and estimated dwell time-defined as the time from the development of an adenoma to symptom-detected cancer in the absence of screening among individuals with a CRC diagnosis.

RESULTS

The 20-year CRC incidence among 55-year-old individuals with an adenoma or preclinical cancer was 7 to 75 times greater than in the condition-free group. The removal of all adenomas among the subgroup with an underlying adenoma or cancer resulted in a reduction of 30% to 89% in cumulative incidence. Among CRCs diagnosed at age 65 years, the proportion arising from adenomas formed within 10 years ranged between 4% and 67%. The mean dwell time varied from 10.6 to 25.8 years.

CONCLUSIONS

Models that all match observed data on adenoma prevalence and cancer incidence can produce quite different dwell times and very different answers with respect to the effectiveness of interventions. When conducting applied analyses to inform policy, using multiple models provides a sensitivity analysis on key (unobserved) "deep" model parameters and can provide guidance about specific areas in need of additional research and validation.

Cost-effectiveness of colorectal cancer screening in high-risk Spanish patients: use of a validated model to inform public policy

BACKGROUND

The European Community has made a commitment to colorectal cancer (CRC) screening, but regional considerations may affect the design of national screening programs. We developed a decision analytic model tailored to a pilot screening program for high-risk persons in Spain with the aim of informing public policy decisions.

MATERIALS AND METHODS

We constructed a decision analytic Markov model based on our validated model of CRC screening that reflected CRC epidemiology and costs in persons with first-degree relatives with CRC in Aragón, Spain, and superimposed colonoscopy every 5 or 10 years from ages 40 to 80 years. The pilot program's preliminary clinical results and our modeling results were presented to regional health authorities.

RESULTS

In the model, without screening, 88 CRC cases occurred per 1,000 persons from age 40 to 85 years. In the base case, screening reduced this by 72% to 77% and gained 0.12 discounted life years per person. Screening every 10 years was cost saving, and screening every 5 years versus every 10 years cost 7,250 euros per life year gained. Based on these savings, 36 to 39 euros per person per year could go toward operating costs while maintaining a neutral budget. If screening costs doubled, screening remained highly cost-effective but no longer cost saving. These results contributed to the health authorities' decision to expand the pilot program to the entire region in 2009.

CONCLUSIONS

Colonoscopic screening of first-degree relatives of persons with CRC may be cost saving in public systems like that of Spain. Decision analytic modeling tailored to regional considerations can inform public policy decisions.

IMPACT

Tailored decision analytic modeling can inform regional policy decisions on cancer screening.

The impact of national guidelines on the waiting list for colonoscopy: a quantitative clinical audit

OBJECTIVE

To assess the compliance of the surveillance colonoscopy waiting list with ACPGBI/BSG guidelines for colonoscopy follow-up and to measure the impact of adjusting referrals to be inline with the guidelines.

DESIGN AND SETTING

This is a quantitative five-stage clinical audit cycle involving a large patient cohort from the Kent and Medway Cancer Network, which includes seven hospitals across four NHS Hospital Trusts and an estimated population of 1.8 million.

PARTICIPANTS

3020 patients were waiting for a surveillance colonoscopy. Their notes were reviewed and the indications for colonoscopy were compared with the ACPGBI/BSG 2002 guidelines.

INTERVENTIONS

Those patients whose referral to the surveillance colonoscopy waiting list was not found to be compliant were adjusted to be inline with the guidelines.

MAIN OUTCOME MEASURES

The impact of adjusting the surveillance colonoscopy waiting list on the diagnostic colonoscopy service was assessed by measuring the average waiting times for a colonoscopy before and after the intervention.

RESULTS

Around 22% (n = 664) of surveillance colonoscopy referrals were inline with the guidelines, 51% (n = 1540) could be cancelled from the list and 27% (n = 816) could be given a new date. Implementing these recommendations reduced the average wait for a diagnostic colonoscopy from 76.8 to 56.0 days (P = 0.0022).

CONCLUSION

Following guidelines for surveillance colonoscopy can reduce waiting times for diagnostic colonoscopy. This allows a faster patient journey for diagnostic colonoscopy and a uniform plan for duration and frequency of surveillance colonoscopy. However, this action promoted serious debate on the social, moral and ethical issues.

Prevention, screening and treatment of colorectal cancer: a global and regional generalized cost effectiveness analysis

BACKGROUND

Regional generalized cost-effectiveness estimates of prevention, screening and treatment interventions for colorectal cancer are presented.

METHODS

Standardised WHO-CHOICE methodology was used. A colorectal cancer model was employed to provide estimates of screening and treatment effectiveness. Intervention effectiveness was determined via a population state-transition model (PopMod) that simulates the evolution of a sub-regional population accounting for births, deaths and disease epidemiology. Economic costs of procedures and treatment were estimated, including programme overhead and training costs.

RESULTS

In regions characterised by high income, low mortality and high existing treatment coverage, the addition of screening to the current high treatment levels is very cost-effective, although no particular intervention stands out in cost-effectiveness terms relative to the others.In regions characterised by low income, low mortality with existing treatment coverage around 50%, expanding treatment with or without screening is cost-effective or very cost-effective. Abandoning treatment in favour of screening (no treatment scenario) would not be cost effective.In regions characterised by low income, high mortality and low treatment levels, the most cost-effective intervention is expanding treatment.

CONCLUSIONS

From a cost-effectiveness standpoint, screening programmes should be expanded in developed regions and treatment programmes should be established for colorectal cancer in regions with low treatment coverage.

Can calcium chemoprevention of adenoma recurrence substitute or serve as an adjunct for colonoscopic surveillance?

OBJECTIVES

The aim of this study was to examine the potential cost-effectiveness of calcium chemoprevention post-polypectomy as a substitute or adjunct for surveillance.

METHODS

We constructed a Markov model of post-polypectomy adenoma recurrence and colorectal cancer (CRC) development, calibrated to data from prospective chemoprevention trials of fiber, calcium, antioxidants, and aspirin. We modeled four scenarios for 50-year-old patients immediately after polypectomy: (i) natural history with no further intervention; (ii) elemental calcium 1,200 mg/day from age 50-80; (iii) surveillance colonoscopy from age 50-80 every 5 years, or 3 years for large adenoma; (iv) calcium + surveillance. Patients were followed up until age 100 or death.

RESULTS

Calcium was cost-effective compared to natural history ($49,900/life-year gained). However, surveillance was significantly more effective than calcium (18.729 versus 18.654 life-years/patient; 76 percent versus 14 percent reduction in CRC incidence) at an incremental cost of $15,900/life-year gained. Calcium + surveillance yielded a very small benefit (0.0003 incremental life-years/patient) compared with surveillance alone, at a substantial incremental cost of $3,090,000/life-year gained.

CONCLUSION

Post-polypectomy calcium chemoprevention is unlikely to be a reasonable substitute for surveillance. It may be cost-effective in patients unwilling or unable to undergo surveillance.

Taishotoyama Symposium Barriers to colorectal cancer screening: economics, capacity and adherence

Colorectal cancer is the second leading cause of cancer death in the United States (U.S.). Fecal occult blood testing has been shown in randomized controlled trials to decrease mortality from colorectal cancer. The incidence and mortality associated with colorectal cancer has also been illustrated to be decreased with sigmoidoscopy and colonoscopy through case-control and prospective cohort studies. Current research focuses on determining which screening strategy is optimal, and how we may improve implementation. Primary screening colonoscopy may be most effective; however, this strategy would require up to 2.6 procedures per patient over their lifetime. Based on the U.S. census this equates to 7.5 million procedures annually; the current capacity in the U.S. is insufficient to provide this strategy for all eligible persons. Computed tomographic or magnetic resonance colonography (virtual colonoscopy) may be an attractive alternative, but capacity is also insufficient for implementation. Moreover, since virtual colonoscopy is a diagnostic but not therapeutic test, economic analysis has illustrated that this strategy will not be cost-effective compared to conventional colonoscopy unless it becomes much less expensive or is associated with greater adherence. Fecal DNA testing is a promising technology but current biomarkers are insufficiently sensitive to constitute a viable strategy. Newer tests such as self-propelled, self-guided endoscopes (Aer-O-Scope), 'active' endoscopes that decrease looping (Neoguide) and colon capsule endoscopy require formal evaluation through clinical trials prior to endorsement for colorectal cancer screening. Less than half of all eligible persons in the U.S. adhere to screening recommendations. Factors associated with screening adherence include the patient's level of education, income, access to health care, a family history of colon cancer, male gender and recommendation from the primary care physician. Conversely, non-adherence is associated with concern over the bowel preparation and fear of discomfort and embarrassment with the procedure. Moreover, it appears that the presence of multiple strategies may be the cause of non-adherence in many cases. Patients who are given a choice of several strategies are less likely to adhere to any strategy than patients who are recommended a single strategy. To increase adherence to colorectal cancer screening it is recommended that the patient be instructed to undergo the test to which they are most likely to adhere. Future research should focus on interventions to improve patient adherence to screening, and on developing accurate tests that will achieve high levels of adherence.

The BSG/ACPGBI guidelines for colonoscopic screening: what are we missing?

INTRODUCTION

Before publication of the British Society of Gastroenterology and Association of Coloproctology of Great Britain and Ireland guidelines in 2002, screening for people with a family history of colorectal cancer was sporadic and largely dependant on unvalidated local guidelines. Since 1990 we have been screening patients with both high and moderate risk family histories of colorectal cancer using local protocols which were more liberal than the new guidelines. In this study, we have analysed the pathology that would have been missed if we had been using the new guidelines in the period 1990-2002.

METHOD

A total of 399 consecutive patients with a positive family history of colorectal malignancy underwent screening endoscopy according to local guidelines. Demographic, endoscopic and pathologic data were prospectively collected. Patients were retrospectively divided into those who would have been screened under the new guidelines (group 1) and those who would not (group 2). The recorded pathology was graded as significant or insignificant and the findings compared between the two groups.

RESULTS

A total of 399 patients underwent 557 endoscopies of which 278 (50%) were indicated under the new guidelines (group 1) and 279 (50%) were not indicated (group 2). A significant pathology or carcinoma was found in 15.8% of group 1 endoscopies and 10.0% of group 2 endoscopies. This difference was significant.

CONCLUSION

If we had been using the new guidelines in the period 1990-2002, we would not have performed 279 (50%) of the 557 procedures, but would not have discovered significant pathology in 10% of the moderate risk endoscopies representing 39% of the significant pathology, which was actually present in this population.

Ethnic differences in colorectal cancer screening

The present study was designed to assess ethnic disparities in CRC screening rates in a low-income population and to examine factors that could account for those differences. Participants were randomly selected and asked to complete a questionnaire about CRC screening. After controlling for gender, age, education, income, health insurance, and family history of CRC, differences in screening rates as a function of ethnicity remained. Physicians' recommendations and perceived efficacy of screening were also strong predictors of CRC screening. Psychological factors accounted in part for differences in screening rates between European Americans and Mexican Americans.

As tests evolve and costs of cancer care rise: reappraising stool-based screening for colorectal neoplasia

BACKGROUND

Colorectal cancer screening and treatment are rapidly evolving. Aims To reappraise stool-based colorectal cancer screening in light of changing test performance characteristics, lower test cost and increasing colorectal cancer care costs.

METHODS

Using a Markov model, we compared faecal DNA testing every 3 years, annual faecal occult blood testing or immunochemical testing, and colonoscopy every 10 years.

RESULTS

In the base case, faecal occult blood testing and faecal immunochemical testing gained life-years/person and cost less than no screening. Faecal DNA testing version 1.1 at $300 (the current PreGen Plus test) gained 5323 life-years/100 000 persons at $16 900/life-year gained and faecal DNA testing version 2 (enhanced test) gained 5795 life-years/100 000 persons at $15 700/life-year gained vs. no screening. In the base case and most sensitivity analyses, faecal occult blood testing and faecal immunochemical testing were preferred to faecal DNA testing. Faecal DNA testing version 2 cost $100 000/life-year gained vs. faecal immunochemical testing when per-cycle adherence with faecal immunochemical testing was 22%. Faecal immunochemical testing with excellent adherence was superior to colonoscopy every 10 years.

CONCLUSIONS

As novel biological therapies increase colorectal cancer treatment costs, faecal occult blood testing and faecal immunochemical testing could become cost-saving. The cost-effectiveness of faecal DNA testing compared with no screening has improved, but faecal occult blood testing and faecal immunochemical testing are preferred to faecal DNA testing when patient adherence is high. Faecal immunochemical testing may be comparable to colonoscopy every 10 years in persons adhering to yearly testing.

Follow-up after colorectal polypectomy: a benefit-risk analysis of German surveillance recommendations

OBJECTIVE

For colorectal screening patients a mean gain of life time was previously calculated of about 30-50 days. Different recommendations for recognising at-risk groups and defining surveillance intervals after an initial finding of colorectal adenomas have been published. However, no benefit-risk analysis regarding to specific long-term effects of follow-up has been reported to date.

MATERIALS AND METHODS

A Markov model based on time-dependent transition possibilities was developed to perform a benefit-risk analysis of the risk-related surveillance recommendations based on the Erlangen Registry of Colorectal Polyps (ERCRP) in comparison with the recommendation of the German Society of Gastrointestinal Diseases and Nutrition (DGVS). The outcome was calculated for a 50-year-old patient with 30 years of follow-up after initial polypectomy. The data used in this model were taken from different sources, namely the ERCRP, the German Study Group of Colorectal Cancer, the German Statistical Yearbook, and from meta-analyses of studies reporting data on complications and sensitivity of colonoscopy.

RESULTS

Patients under surveillance have a mean lifetime gain of 98 (ERCRP) and 110 (DGVS) days compared with those who do not come for surveillance. 84% and 94% of deaths from colorectal carcinoma (CRC) could be prevented if patients were followed up according to the recommendations of the ERCRP and the DGVS, respectively. Less colonoscopies are needed to prevent one death from CRC following the recommendations of the ERCRP (221) than those of the DGVS (283). The risk of death due to colonoscopy for patients during follow-up is about 0.05% lifetime risk. Sensitivity analysis showed the stability of the results under a wide range of reasonable variations of relevant parameters. In a pessimistic one-way sensitivity analysis regarding compliance, effectiveness was reduced to one third.

CONCLUSION

Surveillance using colonoscopy is an effective tool for preventing CRC after colorectal polypectomy, especially if a good compliance is assumed. The effectiveness is higher following the recommendations of the DGVS, but more colonoscopies are needed.

Assessing attitudes toward laxative preparation in colorectal cancer screening and effects on future testing: potential receptivity to computed tomographic colonography

OBJECTIVE

To investigate whether removal of the laxative preparation would improve colorectal cancer (CRC) screening rates. RESPONDENTS AND METHODS: Data are from a mixed-mode mail and telephone survey of 1636 noninstitutionalized Minnesota residents who were 18 years or older that was conducted from July 15 through October 25, 2005. The overall response rate was 49%. Analysis focused on the 759 respondents who were 50 years or older.

RESULTS

One third (32%) of the respondents identified the laxative preparation as the most troublesome part of CRC screening. Overall, the self-reported likelihood and anticipated timing of examination increase when the laxative preparation is removed. Both univariate and multivariate analysis showed that the odds of being "much more likely" to undergo screening in the future with a test that does not include a laxative preparation are greatest among those who have been tested previously, regard the laxative preparation as a big problem, or both.

CONCLUSION

In this prospective survey, laxative preparation appeared to be a major disincentive to CRC screening. Emerging data suggest that performance of laxative-free computed tomographic colonography may represent an attractive option that removes this relatively common disincentive to CRC screening participation.

The cost-effectiveness of CT colonography in screening for colorectal neoplasia

BACKGROUND

We examined the cost-effectiveness of 2- and 3-dimensional computerized tomography (CT) colonography as a screening test for colorectal neoplasia.

METHODS

We created a Markov model of the natural history of colorectal cancer. Effectiveness of screening was based upon the diagnostic accuracy of tests in detecting polyps and cancer.

RESULTS

CT colonography every 5 or 10 yr was effective and cost-effective relative to no screening. Optical colonoscopy dominates 2-dimensional CT colonography done every 5 or 10 yr. Optical colonoscopy is weakly dominant over 3-dimensional CT colonography done every 10 yr. 3-D CT colonography done every 5 yr is more effective than optical colonoscopy every 10 yr, but costs an incremental 156,000 dollars per life-year gained. Sensitivity analyses show that test costs, accuracy, and adherence are critical determinants of incremental cost-effectiveness. 3-D CT colonography every 5 yr is a dominant strategy if optical colonoscopy costs 1.6 times more than CT colonography. However, optical colonoscopy is a dominant strategy if the sensitivity of CT colonography for 1 cm adenomas is 83% or lower.

CONCLUSIONS

CT colonography is an effective screening test for colorectal neoplasia. However, it is more expensive and generally less effective than optical colonoscopy. CT colonography can be reasonably cost-effective when the diagnostic accuracy of CT colonography is high, as with primary 3-dimensional technology, and if costs are about 60% of those of optical colonoscopy. Overall, CT colonography technology will need to improve its accuracy and reliability to be a cost-effective screening option.

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

BACKGROUND & AIMS

Colorectal cancer (CRC) screening is effective and cost-effective, but the potential national impact of widespread screening is uncertain. It is controversial whether screening colonoscopy can be offered widely and how emerging tests may impact health services demand. Our aim was to produce integrated, comprehensive estimates of the impact of widespread screening on national clinical and economic outcomes and health services demand.

METHODS

We used a Markov model and census data to estimate the national consequences of screening 75% of the US population with conventional and emerging strategies.

RESULTS

Screening decreased CRC incidence by 17%-54% to as few as 66,000 cases per year and CRC mortality by 28%-60% to as few as 23,000 deaths per year. With no screening, total annual national CRC-related expenditures were 8.4 US billion dollars. With screening, expenditures for CRC care decreased by 1.5-4.4 US billion dollars but total expenditures increased to 9.2-15.4 US billion dollars. Screening colonoscopy every 10 years required 8.1 million colonoscopies per year including surveillance, with other strategies requiring 17%-58% as many colonoscopies. With improved screening uptake, total colonoscopy demand increased in general, even assuming substantial use of virtual colonoscopy.

CONCLUSIONS

Despite savings in CRC care, widespread screening is unlikely to be cost saving and may increase national expenditures by 0.8-2.8 US billion dollars per year with conventional tests. The current national endoscopic capacity, as recently estimated, may be adequate to support widespread use of screening colonoscopy in the steady state. The impact of emerging tests on colonoscopy demand will depend on the extent to which they replace screening colonoscopy or increase screening uptake in the population.

Colorectal cancer screening: practices and opinions of primary care physicians

BACKGROUND

The Canadian Task Force on Preventive Health Care (CTFPHC), in 2001, concluded that there is good evidence to include annual or biennial fecal occult blood testing (FOBT) and fair evidence to include flexible sigmoidoscopy in the periodic health examination of asymptomatic adults more than 50 years of age.

METHODS

Mailed survey of Alberta primary care physicians to determine current colorectal cancer (CRC) screening practices, familiarity with the new guideline, and opinions about, and barriers to, screening average-risk patients.

RESULTS

Response rate was 58.0% (n = 965). Less than half (41.9%) were familiar with the new Canadian guideline. The majority (74.7%) recommended that asymptomatic patients undergo screening; however, only 35.6% offered screening to at least 75% of average-risk patients. Few (9.4%) rated fecal occult blood as an "excellent or very good" screening test. Most (64.1%) physicians would choose colonoscopy if they themselves were to undergo screening. Concerns were raised about cost-effectiveness, inconsistencies of current recommendations, and resources.

CONCLUSION

Although supportive of colorectal cancer screening of average-risk patients, few physicians recommend screening for the majority of their patients. Clarification of inconsistencies between guidelines, resource issues, and the availability of efficacious screening tests is required for wider acceptance of the new Canadian guideline.

Colorectal neoplasia screening with virtual colonoscopy: when, at what cost, and with what national impact?

BACKGROUND & AIMS

When optimized, virtual colonoscopy may be highly sensitive for colorectal neoplasia. We evaluated the effectiveness and cost-effectiveness of virtual colonoscopy screening (VC) vs. colonoscopy screening (COLO) and the potential impact at the national level.

METHODS

Using a Markov model, we estimated the clinical and economic consequences of VC and COLO from ages 50 to 80 years. Using census data, we made projections to the national level.

RESULTS

In the best case considered (95%, 94%, and 87% sensitivity for colorectal cancer [CRC], polyps > or =10 mm, and polyps <10 mm), VC was nearly as effective as COLO. However, if test costs were equal, total cost per person was 15% greater for VC than COLO, making COLO dominant. When test cost for VC was < or =60% of test cost for COLO, the small benefit of COLO vs. VC cost >200,000 US dollars/incremental life-year. The greater the likelihood of being referred for colonoscopy after VC, the greater the advantage of COLO. With 75% screening adherence in the United States, VC and COLO could decrease CRC incidence by 46%-54%, with COLO requiring 6.9 million colonoscopies/yr, and VC, 3.2 million colonoscopies/yr, plus 5.4 million virtual colonoscopies/yr with VC.

CONCLUSIONS

Even if screening test sensitivities were similar, COLO is likely to be preferred over VC unless virtual colonoscopy costs significantly less than colonoscopy. VC may be most appropriate in persons unlikely to need colonoscopy, such as those at low CRC risk. If VC were substituted for COLO, the demand on resources would shift from endoscopic to radiologic services, but would not diminish.

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

BACKGROUND & AIMS

Fecal DNA testing is an emerging tool to detect colorectal cancer (CRC). Our aims were to estimate the clinical and economic consequences of fecal DNA testing vs. conventional CRC screening.

METHODS

Using a Markov model, we estimated CRC incidence, CRC mortality, and discounted cost/life-year gained for screening by fecal DNA testing (F-DNA), fecal occult blood testing (FOBT) and/or sigmoidoscopy, or colonoscopy (COLO) in persons at average CRC risk from age 50 to 80 years.

RESULTS

Compared with no screening, F-DNA at a screening interval of 5 years decreased CRC incidence by 35% and CRC mortality by 54% and gained 4560 life-years per 100,000 persons at USD $47,700/life-year gained in the base case. However, F-DNA gained fewer life-years and was more costly than conventional screening. The average number of colonoscopies per person was 3.8 with COLO and 0.8 with F-DNA. In most 1-way sensitivity analyses and Monte Carlo simulation iterations, F-DNA remained reasonably cost-effective compared with no screening, but COLO and FOBT dominated F-DNA. Assuming fecal DNA testing sensitivities of 65% for CRC and 40% for large polyp, and 95% specificity, a screening interval of 2 years and a test cost of USD $195 would be required to make F-DNA comparable with COLO.

CONCLUSIONS

Fecal DNA testing every 5 years appears effective and cost-effective compared with no screening, but inferior to other strategies such as FOBT and COLO. Fecal DNA testing could decrease the national CRC burden if it could improve adherence with screening, particularly where the capacity to perform screening colonoscopy is limited.

Comparison of the relative sensitivity of CT colonography and double-contrast barium enema for screen detection of colorectal polyps

BACKGROUND & AIMS

In a population reflective of a screening setting, our aim was to compare the relative sensitivity and specificity of computed tomography (CT) colonography with double-contrast barium enema (DCBE) for detection of colorectal polyps and to assess the added value of double reading at CT colonography, using endoscopy as the arbiter.

METHODS

This prospective, blinded study comprised 837 asymptomatic persons at higher than average risk for colorectal cancer who underwent CT colonography followed by same-day DCBE. Examinations with polyps > or =5 mm in diameter were referred to colonoscopy.

RESULTS

CT colonography readers detected 56%-79% of polyps > or =10 mm in diameter. In comparison, the sensitivity at DCBE varied between 39% and 56% for the 31 polyps > or =1 cm. All of the readers detected more polyps at CT colonography than DCBE, but the difference was statistically significant for only a single reader (P = 0.02). Relative specificity for polyps > or =10 mm on a per-patient basis ranged from 96% to 99% at CT colonography, and 99%-100% at DCBE. Doubly read CT colonography detected significantly more polyps than DCBE (81% vs. 45% for polyps > or =1 cm [P = <0.01], and 72% vs. 44% for polyps 5-9 mm [P < or = 0.01]).

CONCLUSIONS

Double-read CT colonography is significantly more sensitive in detecting polyps than single-read double contrast barium enema. DCBE was significantly more specific than CT colonography.

Cost-effectiveness of colorectal cancer screening: comparison of community-based flexible sigmoidoscopy with fecal occult blood testing and colonoscopy

BACKGROUND AND AIMS

To determine the cost-effectiveness of screening for colorectal cancer using flexible sigmoidoscopy once every 10 years, compared with annual and biennial rehydrated Hemoccult fecal occult blood testing and colonoscopy once every 10 years, or no screening.

METHODS

A Markov model was developed in order to simulate the progression of a cohort of asymptomatic, average-risk individuals aged 55-64 years who were moving through a defined series of states towards death. The main outcome measures were: cases of colorectal cancer averted, colorectal cancer deaths averted, and cost per life-year saved.

RESULTS

Colonoscopy averted the greatest number of cases of colorectal cancer (35%), followed by flexible sigmoidoscopy (25%), and annual (24%) and biennial (14%) fecal occult blood testing. Colonoscopy averted the greatest number of deaths from colorectal cancer (31%), followed by annual fecal occult blood testing (29%), flexible sigmoidoscopy (21%) and biennial fecal occult blood testing (19%). Flexible sigmoidoscopy was the most efficient in terms of cost per life-year saved (16,801 Australian dollars), followed by colonoscopy (19,285 Australian dollars), biennial (41,183 Australian dollars), and annual (46,900 Australian dollars) fecal occult blood testing.

CONCLUSIONS

Flexible sigmoidoscopy and colonoscopy are cost-effective strategies for reducing the disease burden of colorectal cancer.

Computerized tomographic colonography: performance evaluation in a retrospective multicenter setting

BACKGROUND & AIMS

No multicenter study has been reported evaluating the performance and interobserver variability of computerized tomographic colonography. The aim of this study was to assess the accuracy of computerized tomographic colonography for detecting clinically important colorectal neoplasia (polyps >or=10 mm in diameter) in a multi-institutional study.

METHODS

A retrospective study was developed from 341 patients who had computerized tomographic colonography and colonoscopy among 8 medical centers. Colonoscopy and pathology reports provided the standard. A random sample of 117 patients, stratified by criterion standard, was requested. Ninety-three patients were included (47% with polyps >or=10 mm; mean age, 62 years; 56% men; 84% white; 40% reported colorectal symptoms; 74% at increased risk for colorectal cancer). Eighteen radiologists blinded to the criterion standard interpreted computerized tomography colonography examinations, each using 2 of 3 different software display platforms.

RESULTS

The average area under the receiver operating characteristic curve for identifying patients with at least 1 lesion >or=10 mm was 0.80 (95% lower confidence bound, 0.74). The average sensitivity and specificity were 75% (95% lower confidence bound, 68%) and 73% (95% lower confidence bound, 66%), respectively. Per-polyp sensitivity was 75%. A trend was observed for better performance with more observer experience. There was no difference in performance across software display platforms.

CONCLUSIONS

Computerized tomographic colonography performance compared favorably with reported performance of fecal occult blood testing, flexible sigmoidoscopy, and barium enema. A prospective study evaluating the performance of computerized tomography colonography in a screening population is indicated.

An evidence-based medicine approach to economic studies: assessing the cost-effectiveness of competing strategies for colorectal cancer screening

Cost-effectiveness analysis aims to quantitatively compare the expected outcomes of competing management strategies in environments with limited economic resources. A valid economic study models all relevant strategies from an appropriate perspective. The model must use costs that are accurately measured and strategies that have established clinical effectiveness, and appropriately integrate these data. The results should include the incremental cost-effectiveness ratio, which quantifies the resources required to achieve greater benefit with one strategy compared to another. A sensitivity analysis is required to determine whether uncertainty in assumptions alters the conclusions. Final interpretation of a cost-effectiveness analysis relies on whether costs and outcomes in the study can be realized in one's own health care environment.

Prospective blinded evaluation of computed tomographic colonography for screen detection of colorectal polyps

BACKGROUND & AIMS

This study used a low lesion prevalence population reflective of the screening setting to estimate the sensitivity and specificity of computerized tomographic (CT) colonography for detection of colorectal polyps.

METHODS

This prospective, blinded study comprised 703 asymptomatic persons at higher-than-average risk for colorectal cancer who underwent CT colonography followed by same-day colonoscopy. Two of 3 experienced readers interpreted each CT colonography examination.

RESULTS

Overall lesion prevalence for adenomas >/=1 cm in diameter was 5%. Seventy percent of all lesions were proximal to the descending colon. With colonoscopy serving as the gold standard, CT colonography detected 34%, 32%, 73%, and 63% of the 59 polyps >/=1 cm for readers 1, 2, 3, and double-reading, respectively; and 35%, 29%, 57%, and 54% of the 94 polyps 5-9 mm for readers 1, 2, 3, and double-reading, respectively. Specificity for CT colonography ranged from 95% to 98% and 86% to 95% for >1 cm and 5-9-mm polyps, respectively. Interobserver variability was high for CT colonography with kappa statistic values ranging from -0.67 to 0.89.

CONCLUSIONS

In a low prevalence setting, polyp detection rates at CT colonography are well below those at colonoscopy. These rates are less than previous reports based largely on high lesion prevalence cohorts. High interobserver variability warrants further investigation but may be due to the low prevalence of polyps in this cohort and the high impact on total sensitivity of each missed polyp. Specificity, based on large numbers, is high and exhibits excellent agreement among observers.

A simulation model for evaluating the medical and economic outcomes of screening strategies for colorectal cancer

Mathematical models have been shown to be useful in predicting the cost-effectiveness of cancer screening programmes. We designed a computer macro-simulation model aimed at predicting the cost-effectiveness of alternative colorectal cancer screening strategies. This model was built to determine the cost-effectiveness of a biennial screening programme using the Hemoccult test in Burgundy (France). It was validated with data from the Danish randomized study. Estimates of our model showed an extremely close concordance with observed results in the Danish study. The observed mortality reduction was 18.0% and the estimated mortality reduction was 18.4%. Preliminary data from the Burgundy study predict a 14.6% colorectal cancer mortality reduction after 10 years. Sensitivity analyses were performed with different assumptions regarding the participation rates and the lead-time. This model can serve to assess the cost-effectiveness of a variety of screening modalities.

Radiologic imaging modalities in the diagnosis and management of colorectal cancer

Colorectal carcinoma poses a serious public health threat. Detection in its early stages in the best predictor for long-term survival, which is the impetus for population-based screening programs. We believe that full-colon imaging by either DCBE or colonoscopy is necessary for colon cancer screening because flexible sigmoidoscopy, even if perfect, only detects 50% to 60% of colon cancers, a rate far worse than even the worst rate reported for single-contrast barium enema. Screening for colon cancer with flexible sigmoidoscopy is equivalent to performing a "left" mammogram for the detection of breast cancer. The role of CT colonography is still to be determined. When confronted with a symptomatic patient, barium enema is applied in conjunction with CT to detect primary colorectal carcinoma, to differentiate it from other benign and malignant processes involving the colon, and to assess for disease extent before surgery in selected high-risk patient populations. Pelvic MRI may be useful in the preoperative assessment of patients with rectal carcinoma as a means for assisting surgical planning. CT, MRI, and barium enema are used in postoperative follow-up for detecting local recurrence and distant spread. In response to known difficulty in discriminating between normal postoperative changes and tumor recurrence and in determining the nature of certain liver lesions, FDG-PET has been approved for the detection and localization of recurrent colorectal cancer in patients with rising CEA levels and indeterminate findings on standard imaging studies. Given its current promise of offering high sensitivity, specificity, and accuracy, the indications for PET may well expand in the future, but its final role in still to be determined.

Reduction of the incidence and mortality of rectal cancer by polypectomy: a prospective cohort study in Haining County

AIM: To reduce the incidence and mortality of rectal cancer and address the hypothesis that colorectal cancer often arise from precursor lesion (s), either adenomas or non-adenomatous polyps, by conducting a population-based mass screening for colorectal cancer in Haining County, Zhejiang, PRC.

METHODS: From 1977 to 1980, physicians screened the population of Haining County using 15 cm rigid endoscopy. Of over 240000 participants, 4076 of them were diagnosed with precursor lesions, either adenomas or non-adenomatous polyps, which were then removed surgically. All individuals with precursor lesions were followed up and reexamined by endoscopy every two to five years up to 1998.

RESULTS: After the initial screening, 953 metachronous adenomas and 417 non-adenomatous polyps were detected and removed from the members of this cohort. Further, 27 cases of colorectal cancer were detected and treated. Log-rank tests showed that the survival time among those cancer patients who underwent mass screening increased significantly compared to that of other colorectal cancer patients (P < 0.0001). According to the population-based cancer registry in Haining County, age-adjusted incidence and mortality of rectal cancer decreased by 41% and 29% from 1977-1981 to 1992-1996, respectively. Observed cumulative 20-year rectal cancer incidence was 31% lower than the expected in the screened group; the mortality due to rectal cancer was 18% lower than the expected in the screened group.

CONCLUSION: Mass screening for rectal cancer and precursor lesions with protocoscopy in the general population and periodical following-up with routine endoscopy for high-risk patients may decrease both the incidence and mortality of rectal cancer.

The limited incorporation of economic analyses in clinical practice guidelines

BACKGROUND

Because there is increasing concern that economic data are not used in the clinical guideline development process, our objective was to evaluate the extent to which economic analyses are incorporated in guideline development.

METHODS

We searched medline and HealthSTAR databases to identify English-language clinical practice guidelines (1996-1999) and economic analyses (1990-1998). Additional guidelines were obtained from The National Guidelines Clearinghouse Internet site available at http://www.guideline.gov. Eligible guidelines met the Institute of Medicine definition and addressed a topic included in an economic analysis. Eligible economic analyses assessed interventions addressed in a guideline and predated the guideline by 1 or more years. Economic analyses were defined as incorporated in guideline development if 1) the economic analysis or the results were mentioned in the text or 2) listed as a reference. The quality of economic analyses was assessed using a structured scoring system.

RESULTS

Using guidelines as the unit of analysis, 9 of 35 (26%) incorporated at least 1 economic analysis of above-average quality in the text and 11 of 35 (31%) incorporated at least 1 in the references. Using economic analyses as the unit of analysis, 63 economic analyses of above-average quality had opportunities for incorporation in 198 instances across the 35 guidelines. Economic analyses were incorporated in the text in 13 of 198 instances (7%) and in the references in 18 of 198 instances (9%).

CONCLUSIONS

Rigorous economic analyses may be infrequently incorporated in the development of clinical practice guidelines. A systematic approach to guideline development should be used to ensure the consideration of economic analyses so that recommendations from guidelines may impact both the quality of care and the efficient allocation of resources.

Which colon cancer screening test? A comparison of costs, effectiveness, and compliance

PURPOSE

Recent media reports have advocated the use of colonoscopy for colorectal cancer screening. However, colonoscopy is expensive compared with other screening modalities, such as fecal occult blood testing and flexible sigmoidoscopy. We sought to determine the cost effectiveness of different screening strategies for colorectal cancer at levels of compliance likely to be achieved in clinical practice.

METHODS

A Markov decision model was used to examine screening strategies, including fecal occult blood testing alone, fecal occult blood testing combined with flexible sigmoidoscopy, flexible sigmoidoscopy alone, and colonoscopy. The timing and frequency of screening was varied to assess optimal screening intervals. Sensitivity analyses were conducted to assess the factors that have the greatest effect on the cost effectiveness of screening.

RESULTS

All strategies are cost effective versus no screening, at less than $20,000 per life-year saved. Direct comparison suggests that the most effective strategies are twice-lifetime colonoscopy and flexible sigmoidoscopy combined with fecal occult blood testing. Assuming perfect compliance, flexible sigmoidoscopy combined with fecal occult blood testing is slightly more effective than twice-lifetime colonoscopy (at ages 50 and 60 years) but is substantially more expensive, with an incremental cost effectiveness of $390,000 per additional life-year saved. However, compliance with primary screening tests and colonoscopic follow-up for polyps affect screening decisions. Colonoscopy at ages 50 and 60 years is the preferred test regardless of compliance with the primary screening test. However, if follow-up colonoscopy for polyps is less than 75%, then even once-lifetime colonoscopy is preferred over most combinations of flexible sigmoidoscopy and fecal occult blood testing. Costs of colonoscopy and proportion of cancer arising from polyps also affect cost effectiveness.

CONCLUSIONS

Colonoscopic screening for colorectal cancer appears preferable to current screening recommendations. Screening recommendations should be tailored to the compliance levels achievable in different practice settings.

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.

Gastrointestinal tract cancer in the elderly

Gastrointestinal cancers are common in the elderly. In the 1990s, modest advances in the early diagnosis, staging, and treatment of gastrointestinal cancers were made. Emphasis has been placed on screening for colorectal cancer; development of new diagnostic and staging modalities, particularly endoscopic ultrasound; and introduction of new treatment regimens, such as chemoradiation programs for esophageal, pancreatic, and colorectal cancers as well as endoscopic mucosal resection of early gastrointestinal cancers. New palliative techniques, such as laser and photodynamic therapy and placement of enteral stents, are being used increasingly in patients who have advanced cancer and are not surgical candidates. In the past, attitudes toward the elderly affected the management of cancer. Age should not be the only parameter considered when addressing the treatment of a gastrointestinal malignancy. Management decisions in the elderly should follow the same principles as those in younger patients. A thorough medical evaluation in the elderly is necessary to evaluate the patient's risk and to optimize surgical, chemotherapeutic, and palliative outcomes.

Design of the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial

The objectives of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial are to determine in screenees ages 55-74 at entry whether screening with flexible sigmoidoscopy (60-cm sigmoidoscope) can reduce mortality from colorectal cancer, whether screening with chest X-ray can reduce mortality from lung cancer, whether screening men with digital rectal examination (DRE) plus serum prostate-specific antigen (PSA) can reduce mortality from prostate cancer, and whether screening women with CA125 and transvaginal ultrasound (TVU) can reduce mortality from ovarian cancer. Secondary objectives are to assess screening variables other than mortality for each of the interventions including sensitivity, specificity, and positive predictive value; to assess incidence, stage, and survival of cancer cases; and to investigate biologic and/or prognostic characterizations of tumor tissue and biochemical products as intermediate endpoints. The design is a multicenter, two-armed, randomized trial with 37,000 females and 37,000 males in each of the two arms. In the intervention arm, the PSA and CA125 tests are performed at entry, then annually for 5 years. The DRE, TVU, and chest X-ray exams are performed at entry and then annually for 3 years. Sigmoidoscopy is performed at entry and then at the 5-year point. Participants in the control arm follow their usual medical care practices. Participants will be followed for at least 13 years from randomization to ascertain all cancers of the prostate, lung, colorectum, and ovary, as well as deaths from all causes. A pilot phase was undertaken to assess the randomization, screening, and data collection procedures of the trial and to estimate design parameters such as compliance and contamination levels. This paper describes eligibility, consent, and other design features of the trial, randomization and screening procedures, and an outline of the follow-up procedures. Sample-size calculations are reported, and a data analysis plan is presented.

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.

Accuracy of double-contrast barium enema in diagnosing colorectal polyps and cancer

CRC is a common malignancy, and reduced mortality can be achieved through detection and treatment of early cancers and by removal of colonic adenomas. Although current screening recommendations, especially in the average-risk individual, typically promote the use of FOBT and FS, a substantial minority of colonic cancers and many colonic adenomas are not detected by these methods. Modalities that examine the entire colon, such as the barium enema and colonoscopy, can detect most clinically important colorectal neoplasms; however, their additional costs and potential risks have limited their use as initial screening examinations. But recent changes in governmental policies regarding reimbursement for CRC screening and increasing emphasis on total colon examinations have altered these recommendations. This review on the accuracy of the DCBE has emphasized the detection of colonic polyps and cancers and has updated the changing role of this examination in screening patients at variable risk for CRC. The efficacy of the barium enema depends on many factors that radiologists must understand and control to perform accurate examinations. Current recommendations for CRC screening and approved reimbursement of the barium enema for that purpose provide a new impetus to radiologists to maintain and improve their skills in performing and interpreting this radiologic examination. The barium enema may have a future in the new millennium.

Cost-utility of one-time colonoscopic screening for colorectal cancer at various ages

OBJECTIVE

One-time colonoscopy has been recommended as a possible colorectal cancer (CRC) screening strategy. Because the incidence of colorectal neoplasia increases with age, the effectiveness and cost of this strategy depend on the age at which screening occurs. The purpose of this study was to investigate the age-dependent cost-utility of one-time colonoscopic screening.

METHODS

We constructed a computer simulation model of the natural history of colorectal neoplasia. This model was used to compare the cost-utility of no screening and age-based strategies employing one-time colonoscopic screening (age ranges evaluated: 45-49, 50-54, 55-59, and 60-64 yr).

RESULTS

We determined that one-time colonoscopic screening in men age <60 yr and in women age <65 yr dominates never screening and screening at older ages. For both sexes, one-time colonoscopic screening between 50 and 54 yr of age is associated with a marginal cost-utility of less than $10,000 per additional quality-adjusted life-year compared to screening between 55 and 60 yr of age. One-time colonoscopic screening between 45 and 49 yr of age is either dominated (women) or associated with a marginal cost-utility of $69,000/per quality-adjusted life-year (men) compared to screening between 50 and 54 yr of age. The marginal cost-utility of one-time colonoscopic screening is relatively insensitive to plausible changes in the cost of colonoscopy, the cost of CRC treatment, the sensitivity of colonoscopy for colorectal neoplasia, the utility values representing the morbidity associated with the CRC-related health states, and the discount rate.

CONCLUSIONS

One-time colonoscopic screening between 50 and 54 yr of age is cost-effective compared to no screening and screening at older ages in both men and women. Screening in men between 45 and 49 yr of age may be cost-effective compared to screening between 50 and 54 yr of age depending on societal willingness to pay.

Screening for colorectal cancer

Colorectal cancer is the third most commonly diagnosed cancer and the second leading cause of cancer deaths in the United States. Fortunately, both the incidence and mortality associated with the disease have declined during the past 2 decades. This is likely due, at least in part, to improved efforts at screening and more aggressive removal of adenomatous polyps. However, colorectal cancer screening is still generally underutilized. This article reviews the current status and future outlook for colorectal cancer screening, including a discussion of risk factors for the disease, its anatomic distribution, proposed mechanisms of development from adenomatous polyps, rationale for screening, and screening options. Published literature concerning the cost-effectiveness of colorectal cancer screening is also summarized. The article concludes with a discussion of the emerging consensus regarding the importance of and approaches to screening.

How accurate is the endoscopist's assessment of visualization of the left colon seen at flexible sigmoidoscopy?

OBJECTIVE

There are concerns that the left colon may be incompletely examined by the standard 60-cm flexible sigmoidoscope. Our objective was to compare the endoscopist's assessment of the length of colon seen with the actual length visualized.

PATIENTS AND METHODS

During flexible sigmoidoscopy, endoscopists were asked to state how far they had reached. This was compared with the length of colon actually seen, assessed by a novel electromagnetic imaging (EMI) device that records the three-dimensional position of the scope within a magnetic field pervading the patient's abdomen. If EMI showed that the splenic flexure had not been reached, the endoscopist was asked to use the imager to see if it helped advance the scope further.

RESULTS

In 94 patients, the endoscopist's assessment of position reached was correct in only 47 cases (50%), with an overestimate of length of colon visualized in 24 (25.5%) and an underestimate in 23 (24.5%). EMI showed the splenic flexure had not been reached in 56 patients (59.6%). Using information from the EMI system, further progress was subsequently made in 45/56 (80.4%).

CONCLUSION

Caution is required in the diagnosis of rectal bleeding using flexible sigmoidoscopy alone. This has implications for the use of the 60-cm flexible sigmoidoscope as a screening tool.

Colorectal cancer screening: a community case-control study of proctosigmoidoscopy, barium enema radiography, and fecal occult blood test efficacy

OBJECTIVE

To examine the effectiveness of screening proctosigmoidoscopy, barium enema radiography, and the fecal occult blood test (FOBT) in decreasing colorectal cancer mortality in a community setting.

PATIENTS AND METHODS

In this population-based case-control study, cases comprised 218 Rochester, Minn, residents who died of colorectal cancer between 1970 and 1993. Controls were 435 age- and sex-matched residents who did not have a diagnosis of colorectal cancer. Screening proctosigmoidoscopy, barium enema radiography, and FOBT results were documented for the 10 years prior to and including the date of diagnosis of fatal colorectal cancer in cases and for the same period in matched controls. History of general medical examinations and hospitalizations was also recorded.

RESULTS

Within the 10 years prior to diagnosis, the percentages of cases vs controls with at least 1 screening proctosigmoidoscopy were 23 (10.6%) of 218 cases vs 43 (9.9%) of 435 controls; at least 1 screening barium enema radiographic study was done in 12 (5.5%) of 218 vs 25 (5.7%) of 435. Within 3 years prior to diagnosis, the percentages of cases vs controls with at least 1 screening FOBT were 27 (12.4%) of 218 vs 44 (10.1%) of 435. Adjusted odds ratios were 1.04 (95% confidence interval [CI], 0.21-5.13) for proctosigmoidoscopy (distal rectosigmoid cancers only), 0.67 (95% CI, 0.31-1.48) for barium enema radiography, and 0.83 (95% CI, 0.45-1.52) for FOBT over the above time periods.

CONCLUSION

In this case-control study within a community setting, a colorectal cancer-specific mortality benefit could not be demonstrated for screening by FOBT, proctosigmoidoscopy, or barium enema radiography. Screening frequency was low, which may have contributed to the lack of measurable effects.

Screening for colorectal cancer: present, past and future

Colorectal cancer results in 18,000 deaths annually in England and Wales, with 24,000 new cases diagnosed each year. Despite a better understanding of the genetics, and advancement in surgical and anaesthetic techniques, there has been little reduction in mortality and morbidity from this disease over the past 25 years. Colorectal cancer fits recognized criteria for a disease that should be screened in asymptomatic individuals. The putative duration of the adenoma to carcinoma sequence gives an ample window of opportunity to detect and treat colorectal cancer. In this article we have reviewed the strategies involved in screening for colorectal cancer in an asymptomatic population. We have presented trials and arguments for and against the different screening methods and discussed cost effectiveness of screening. In the USA and Canada, major professional organizations and societies now endorse screening; in the UK it is still far from being accepted. We feel that the available evidence shows that colorectal cancer screening has the potential to reduce the morbidity and mortality from this disease and that funding for a mass screening and public education programme should be sought.

Molecular advances in the etiology and treatment of colorectal cancer

The diagnosis and treatment of colorectal cancer remains a formidable health care problem. Colorectal cancer is the second most frequently diagnosed cancer in both men and women in Western countries and accounts for over 55,000 deaths annually in the United States alone. Cancer of the colon and rectum is eminently curable by surgical resection if identified early; however, despite our best efforts, patient survival from this disease has changed little over the past 50 years. With the advent of molecular and genetic techniques, a number of novel discoveries have been made in the last decade which have greatly expanded our understanding of the etiology and cellular mechanisms contributing to the development and subsequent progression of colorectal cancer. This review summarizes the recent molecular advances in the understanding of both familial (HNPCC and FAP) and sporadic colorectal cancers. The numerous scientific advances described in this review offer the promise of the development of novel chemotherapeutic agents, more accurate prognostic indicators and better screening techniques.

An assessment of the use of costs and quality of life as outcomes in endoscopic research

BACKGROUND

Costs and quality of life are increasingly important study outcomes. We quantitatively and qualitatively assessed their use in recent endoscopic research.

METHODS

All Medline-retrieved 1985 to 1995 published gastrointestinal endoscopic research using cost and/or quality of life as outcomes were analyzed.

RESULTS

Sixty-eight (1.2%) of an estimated 5568 publications discussed costs and/or quality of life as endoscopic outcomes (24 quality of life, 37 cost-effectiveness, 7 cost-benefit). Their use did not increase with time. Cost or quality of life was infrequently a primary study outcome. Twenty of 24 (83%) quality of life papers used an objective scale. However, of these, 15 of 20 (75%) used symptom indexes, performance scales, or other nonvalidated quality of life instruments. Two of 24 (8%) evaluated quality of life in nonmalignant disease. Eight of 40 (20%) papers claimed endoscopy was cost-effective, with no evidence of formal cost assessment. Ten of 32 (31%) substituted charges for costs. Of 21 papers reporting cost data, 4 (19%) specified cost type (e.g., direct vs other), 6 (29%) specified cost perspective, and 9 (43%) reported sensitivity analysis. Sixteen of 27 (59%) cost-effectiveness papers did not correlate costs with changes in a health outcome.

CONCLUSIONS

The overall cost and quality of life assessment in endoscopic research has been limited and must be improved. Accurate cost and quality of life assessment will require cooperation between gastroenterologists and experts in these fields.

Screening and surveillance for colorectal carcinoma

Screening and surveillance examinations are effective in lowering colorectal cancer risk. Screening tests have been demonstrated to reduce colorectal cancer mortality. Colonoscopic removal of adenomatous polyps has been determined to reduce colorectal cancer incidence. High-risk individuals and their family members should be identified and offered more aggressive recommendations for appropriate screening and surveillance guidelines. Colorectal cancer screening strategies are in an acceptable range of cost effectiveness.

Results of a pilot study of endoscopic screening of first degree relatives of colorectal cancer patients in Italy

STUDY OBJECTIVE

Screening recommendations for colorectal cancer include sigmoidoscopy in asymptomatic, average risk persons aged 50 and over and colonoscopy every three to five years in high risk groups. Little is known about the eligible population's compliance with endoscopic screening. This is the first Italian report of an endoscopic screening programme for colorectal cancer patients' relatives.

DESIGN

In 1986, a pilot project for colorectal cancer screening by endoscopy in high risk subjects was started in the Desio (Milan, Italy) public health service region. The results obtained after seven years are described.

SETTING

The names of 536 inhabitants with colorectal cancer diagnosed between January 1975 and December 1984 and their relatives' addresses were obtained from the Regione Lombardia Health System records and from the municipal registry offices respectively.

PARTICIPANTS

From October 1986 to October 1993, 778 first degree relatives aged 20-75 were offered colonoscopy.

MAIN RESULTS

After seven years, 233 (29.9%) had undergone endoscopic examination, mostly up to the splenic flexure. Being > 60 in age at the start of the programme negatively affected the participation (p < 0.05). Two cancers were detected and adenomatous polyps were found in another 24 of those screened (frequencies 0.9% and 10.3% respectively). Male gender (p < 0.05), increasing age in males (p < 0.01), and two or more affected relatives in females (p < 0.01) positively affected the frequency of polyps detection.

CONCLUSION

These results suggest that about 30% of the eligible population would comply at least with sigmoidoscopic screening. The collaboration of family doctors and more widespread public information about the ability to cure colorectal cancer are necessary for better compliance.