Effectiveness Of Colorectal Cancer Screening Research Articles

The effect of colorectal cancer screening mandates on access to care and clinical outcomes: A retrospective study of patients undergoing operations of the colon and rectum

Policies that mandate colorectal screening coverage by private insurers are associated with increased use of screening procedures. We seek to understand whether such mandates have improved access to care and short-term operative outcomes for patients undergoing operations of the colon and rectum (OCR). Privately insured OCR patients, ages 50-64, enrolled in the Nationwide Inpatient Sample (NIS) (2000-2009) were identified. Patients were classified as "exposed" if they underwent OCR in a state that implemented a mandate ≥ 2 years before their procedure. Three outcomes were examined: admission source, postoperative complications, and postoperative mortality. Univariate analyses were performed by the use of logistic regression models. Multivariable logistic regression models were developed to evaluate the relationship between exposure status, admission source, postoperative complications, and postoperative mortality, with adjustment for confounders. We identified 99,405 patients who underwent OCR during the study period. Of these patients, 39% were "exposed," 23% were admitted from the ED, 32% developed a postoperative complication, and 2% died during the admission. After adjusting for confounders, exposed patients were less likely to access OCR through the emergency department (odds ratio 0.87; 95% confidence interval 0.83-0.91) and less likely to develop postoperative complications (odds ratio 0.94; 95% confidence interval 0.89-0.98). There was no detectable difference in postoperative mortality. Implementation of policies mandating coverage of colorectal screening modestly reduced emergent admission for OCR among privately insured patients. Additional studies are required to examine the screening status of patients to determine causality. Remaining states should consider implementing similar policies.

Blood RNA biomarker panel detects both left- and right-sided colorectal neoplasms: a case-control study

BackgroundColonoscopy is widely regarded to be the gold standard for colorectal cancer (CRC) detection. Recent studies, however, suggest that the effectiveness of colonoscopy is mostly confined to tumors on the left side of the colon (descending, sigmoid, rectum), and that the technology has poor tumor detection for right-sided (cecum, ascending, transverse) lesions. A minimally invasive test that can detect both left-sided and right-sided lesions could increase the effectiveness of screening colonoscopy by revealing the potential presence of neoplasms in the right-sided “blind spot”.MethodsWe previously reported on a seven-gene, blood-based biomarker panel that effectively stratifies a patient’s risk of having CRC. For the current study, we assessed the effectiveness of the seven-gene panel for the detection of left- and right-sided CRC lesions. Results were evaluated for 314 patients with CRC (left-sided: TNM I, 65; TNM II, 57; TNM III, 60; TNM IV, 17; unknown, 9. right-sided: TNM I, 28; TNM II, 29; TNM III, 38; TNM IV, 12; unknown, 1 and including two samples with both left and right lesions) and 328 control samples. Blood samples were obtained prior to clinical staging and therapy. Most CRC subjects had localized disease (stages I and II, 58%); regional (stage III) and systemic (stage IV) disease represented 32% and 9%, respectively, of the study population.ResultsThe panel detected left-sided (74%, 154/208) and right-sided (85%, 92/108) lesions with an overall sensitivity of 78% (215/316) at a specificity of 66% (215/328). Treatable cancer (stages I to III) was detected with left-sided lesion sensitivity of 76% (138/182) and right-sided sensitivity of 84% (80/95).ConclusionThis seven-gene biomarker panel detected right-sided CRC lesions across all cancer stages with a sensitivity that is at least equal to that for left-sided lesions. This study supports the use of this panel as the basis for a patient-friendly, blood-based test that can be easily incorporated into a routine physical examination in advance of colonoscopy to provide a convenient companion diagnostic and a pre-screening alert, ultimately leading to enhanced CRC screening effectiveness.

In the era of widespread endoscopy use, randomized trials may strongly underestimate the effects of colorectal cancer screening

ObjectivesAlthough randomized controlled trials (RCTs) are considered the most valid approach to evaluate screening effects, they also face a number of methodological challenges, including nonadherence and contamination. We aimed to quantify their potential impact in RCTs evaluating endoscopic screening for colorectal cancer (CRC). Study Design and SettingWe carried out model calculations using plausible levels of nonadherence and contamination. ResultsAssuming medium values of adherence (70%) and contamination, that is, use of lower gastrointestinal endoscopy other than the one offered for screening (30%), true reductions in CRC incidence or mortality of 70%, 50%, or 30% would be expected to be attenuated to reductions of 43%, 29%, and 16%, respectively, in intention-to-screen analyses. In case of low levels of adherence (50%) and high but realistic levels of contamination (50%), even more severe attenuation of screening effects to estimated reductions of 27%, 17%, and 9% would be expected. The estimates are only slightly modified in sensitivity analyses, additionally allowing for differential adherence and contamination according to CRC risk. ConclusionIn the era of widespread endoscopy use even outside the screening programs, RCTs may strongly underestimate the effects of CRC screening. Additional analyses accounting for nonadherence and contamination are crucial for disclosing the true screening effects.

Translational medicine of colorectal cancer

Translational medicine is a systemic project because it is patient and clinical problems oriented, aiming at research results application, and involves multidisciplinary cooperation. Studies on molecular events in the precancerous stage, early stage and metastasis of colorectal cancer (CRC) are the CRC hot research topics currently. Investigations on the earliest molecular events can help to find out the markers which may improve the effect of CRC screening and predict CRC liver metastasis and prognosis. Based on the concept of micro environment, molecular targeted drugs to interfere with metastasis and invasion and new concepts of surgical resection margin and neoadjuvant therapy will gain recognition from clinicians.

What Should Be Done to Increase Survival in Patients With Colorectal Cancer?

See Article on Page 144-150 As a result of its rapid increase, colorectal cancer (CRC) in Korea was the third most common cancer in 2010. The age-standardized incidence rate of CRC was 20.4 (per 100,000) in 1999 and increased to 35.9 in 2010 (annual percentage changes, 5.9%). In 2010, 25,782 new CRC cases (15,612 men and 9,918 women) were diagnosed [1]. The article used the Korea Central Cancer Registry (226,352 cases) to show that the 5-year relative survival rates had improved between 1993 and 2010 (55.4% for 1993-1995 and 72.6% for 2006-2010) [2]. The rapid increase in CRC incidence is mainly attributed to the increase in colon cancer, especially distal colon cancer, and may be explained by a transition of risk factors for subsites or by the effect of CRC screening. The survival improvement may be due to an increase in early detection, refinement of surgical technique, new chemotherapy agents, and a multidisciplinary approach. CRC screening is a common denominator of the rapid increase in the incidence rate and the improved survival. CRC screening programs were introduced in 2004 as a part of the National Cancer Screening Program for Medical Aid recipients and National Health Insurance beneficiaries in the lower income bracket. Fecal occult blood test (FOBT) is provided free of charge as a primary modality for men and women aged 50 years or older. FOBT-positive individuals are provided follow-up by either colonoscopy or double-contrast barium enema. The participation rate was only 10.5% in 2004, but it increased to 21.1% in 2008 [3]. We colorectal surgeons still have a long way to go before we achieve our goal of complete healing of CRC. An expansion of an adherent to CRC screening program and an extension to surveillance colonoscopy without FOBT are the crux of the matter.

Increasing trend of colorectal cancer incidence in Korea, 1999-2009.

PurposeThis study was conducted in order to demonstrate changing trends in colorectal cancer incidence according to sex, age group, and anatomical location in the Korean population.Materials and MethodsData from the Korea Central Cancer Registry between 1999 and 2009 were analyzed. Annual percent changes (APCs) of sex- and age-specific incidence rates for cancer of the proximal colon (International Statistical Classification of Diseases and Related Health Problems, 10th revision [ICD-10] code C18.0-18.5), distal colon (C18.6-18.7), and rectum (C19-20), and male-to-female incidence rate ratios (IRR) were calculated.ResultsThe age-standardized incidence rate (ASR) of colorectal cancer was 27 (per 100,000) in 1999 and increased to 50.2 in 2009 among men (APC, 6.6%). The ASR for women was 17.2 in 1999 and 26.9 in 2009 (APC, 5.1%). The rectum was the most common site of cancer among both men and women during 1999 and 2009. However, the distal colon had the highest APC (10.8% among men and 8.4% among women), followed by the proximal colon (7.9% among men and 6.6% among women), and rectum (5.2% among men and 2.4% among women). The proportion of rectal cancer decreased from 51.5% in 1999 to 47.1% in 2009 among men, and from 50.5% to 42.8% among women. An increase in the male-to-female IRR was observed for distal colon cancer and rectal cancer, whereas the IRR for proximal colon cancer was stable.ConclusionThe rapid increase in colorectal cancer incidence is mainly attributed to the increase in colon cancer, especially distal colon cancer, and may be explained by a transition of risk factors for subsites or by the effect of colorectal cancer screening.

Colorectal cancer screening

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

Next-Generation Stool DNA Testing: Expanding the Scope

Stool DNA testing has emerged as a noninvasive approach to colorectal cancer screening. As with fecal occult blood testing, stool DNA testing offers userfriendly features of noninvasiveness, avoidance of unpleasant purgative bowel preparation, and the potential for markedly increased access via off-site sample collection and shipping. Added advantages of stool DNA testing include sampling of a single stool rather than multiple stools per screen, no diet or medication restriction, and possibly reduced screen frequency because of its capacity to detect precursor lesions. Various technical challenges that compromised first-generation stool DNA tests have been rigorously addressed with more recent laboratory methodologies. Advances in technology promise to strengthen assay performance of stool DNA testing and allow expanded and new clinical applications. Next generation stool DNA tests have the potential to improve the effectiveness of colorectal cancer screening, open the door to screening of gastrointestinal (GI) neoplasms above the colon, and spawn other novel uses.

Adverse Effects of Colorectal Cancer Screening with Fecal Occult Blood Test: A Population-Based Organized Program

Adverse effects (AE) of colorectal cancer (CRC) screening have not yet been assessed as thoroughly as those of mammography screening. Aim: to assess 1) AE of a CRC screening program with guaiac-based fecal occult blood test (gFOBT) and 2) the optimal method for their routine detection. Methods: Identification of AE of the organized CRC screening program with biennial gFOBT in progress in the Haut-Rhin since 2003 through 1) voluntary reporting by gastroenterologists, 2) AE report forms by general practitioners (GPs), 3) retrospective questionnaire mailed to GPs and 4) retrospective questionnaire mailed to persons explored by colonoscopy. Results: 114,137 persons completed 173,352 gFOBTs in 4 years. 2194 of 3810 colonoscopic procedures displayed no neoplasia that is a 57.6% false positive rate. Overall, 17 (4.5/1000) serious AE were recorded: 4 (1.0/1000) perforations, 8 (2.1/1000) bleeding, 3 postpolypectomy syndromes and 2 major anxiety attacks. They resulted in 15 hospitalizations, 6 colonoscopic procedures, 5 surgical operations and 3 blood transfusions. 10 (58.8%) were voluntarily reported by gastroenterologists, 8 (47.1%) were notified by GPs answering the questionnaire and 1 through the AE report form and 7 (41.2%) by patients via the questionnaire. 4 undue surgical operations were recorded, 1 due to an erroneous CT diagnosis of CRC and 3 to an erroneous pathologic overdiagnosis of T1 malignant polyp. 50 colonoscopic procedures were repeated within 6 months without justification. 2288 (61.6%) persons explored by colonoscopy answered the questionnaire and reported 252 (11.1%) minor AE such as abdominal pain after the procedure (50 cases), change in bowel habits (59 cases), bloating (62 cases), nausea/vomiting (16 cases) and fever (11 cases). 494 (21.6%) reported stress when receiving the mail announcing the positive result, 397 (17.4%) judged the bowel preparation awful and 86 (3.8%) experienced pain during colonoscopy. 16 complained about the waiting period before the colonoscopy appointment. 305 GPs (51.4%) answered the questionnaire concerning 1877 patients and notified 80 AE (4.3%). Only 6 AE were reported with the AE report forms. Conclusion: Provided they are actively sought, AE of CRC screening with gFOBT are more frequent than previously reported. Though most of them are minor, the invited population should be informed. The detection of AE must rely on several sources of information. Voluntary reporting by gastroenterologists detects only the half of serious AE. The patient's questionnaire is the most sensitive method for the detection of minor AE and should be routinely proposed to persons screened by colonoscopy.

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

Several randomized studies have shown that colorectal cancer (CRC) screening by faecal occult blood test (FOBT) reduces CRC mortality. These trials have different designs, especially concerning FOBT frequency and duration, as well as the length of follow-up after stopping FOBT campaigns. To review the effectiveness of screening for CRC with FOBT, to consider the reduction in mortality during or after screening or to identify factors associated with a significant mortality reduction. A systematic review of trials of FOBT screening with a meta-analysis of four controlled trials selected for their biennial and population-based design. The main outcome measurements were mortality relative risk (RR) and 95% confidence interval (CI) of biennial FOBT during short (10 years, i.e. five or six rounds) or long-term (six or more rounds) screening periods, as well as after stopping screening and follow-up during 5-7 years. The meta-analysis used the Mantel-Haenszel method with fixed effects when the heterogeneity test was not significant, and used 'intent to screen' results. Although the quality of the four trials was high, only three were randomized, and one used rehydrated biennial FOBT associated with a high colonoscopy rate (28%). A meta-analysis of mortality results showed that subjects allocated to screening had a reduction of CRC mortality during a 10-year period (RR 0.86; CI 0.79-0.94) although CRC mortality was not decreased during the 5-7 years after the 10-year (six rounds) screening period, nor in the last phase (8-16 years after the onset of screening) of a long-term (16 years or nine rounds) biennial screening. Whatever the design of the period of ongoing FOBT, CRC incidence neither decreased nor increased, although it was reduced for 5-7 years after the 10-year screening period. Neither the design nor the clinical or demographic parameters of these trials were independently associated with CRC mortality reduction. Biennial FOBT decreased CRC mortality by 14% when performed over 10 years, without evidence-based benefit on CRC mortality when performed over a longer period. No independent predictors of CRC mortality reduction have been identified in order to allow a CRC screening programme in any subgroups of subjects at risk.

Colon Cancer Screening in 2005: Status and Challenges

The field of colon cancer screening has evolved dramatically in the last 15 years regarding evidence, guidelines, and practice. In 1990, no evidence from a randomized controlled clinical trial (RCT) existed to show that colorectal cancer (CRC) screening was effective in reducing CRC mortality. In 1990, although some guidelines endorsed screening, there was disagreement among recommending organizations about which tests to recommend or whether to recommend any screening tests at all. The US Preventive Services Task Force (USPSTF), arguably the most influential of the recommending organizations and the most rigorously evidence based, said that evidence was insufficient to recommend either for or against CRC screening.1 In this environment, CRC screening was not widely practiced, much less reimbursed by payers. If screening was performed at all, fecal occult blood testing (FOBT) was the most common test. Sigmoidoscopy was performed less frequently, and colonoscopy, rarely performed for screening, was used mainly for workup of a positive FOBT or sigmoidoscopy and for postpolypectomy surveillance. The primary questions facing academics, recommending organizations, and practicing clinicians in 1990 were (1) does CRC screening—of any kind—work to reduce CRC mortality, and (2) should it be implemented and reimbursed? In 2005, the situation is dramatically different. We now know that CRC screening works, and it is now being implemented and reimbursed. Colonoscopy has become popular as a primary screening test, and new tests, such as virtual colonoscopy, are being developed. The purpose of this article is to identify current challenges in light of the evolution of evidence, guidelines, and practice and to anticipate the next phase of development and implementation.

The Stool DNA Test

The stool DNA test is considered an emerging technology in screening for colorectal cancer. The stool DNA test detects DNA markers which are shed from cells of premalignant adenomas and cancers into the stool. Potentially, both preclinical and clinical colorectal cancer may be detected. Panels of multiple DNA markers are used to ensure a high sensitivity for colorectal cancer. In this article, several advantages of the stool DNA test (compared with current colorectal cancer screening methods) are discussed. The stool DNA test may be more patient-friendly and has a higher degree of sensitivity and specificity for colorectal cancer. No bowel or dietary preparation is required and the test is noninvasive. The stool DNA test screens the entire colon and may detect some other types of cancers proximal to the colon. In the future, there may be potential to use the stool DNA test to screen for aerodigestive cancers (lung, esophageal, gastric, and pancreatic), in addition to colorectal cancer. An improved noninvasive screening test would help allocate colonoscopy resources to those patients who would benefit the most. Colorectal cancer screening cost-effectiveness may also be improved. Some limitations of the stool DNA test include the need for clinical studies in average-risk populations and marker refinement. An automated testing system may help reduce costs and turnaround times. Despite recognized limitations, the stool DNA test is a promising new diagnostic tool with the potential to improve effectiveness of colorectal cancer screening.

Factors associated with colorectal cancer screening in a population-based study: the impact of gender, health care source, and time

Introduction. The effectiveness of colorectal cancer screening in reducing incident colorectal cancer and the risk of death has been shown. Despite campaigns to promote the benefits of and use of colorectal cancer screening, most people are not participating in screening. In this paper, we examine factors associated with screening behavior over time, by health care provider, and by gender and report associations between screening and development of colorectal cancer after adjusting for diet and lifestyle factors. Methods. Data from two population-based case-control studies of colorectal cancer were used to examine risk associations with nonparticipation in colorectal cancer screening. Study participants were identified for the first study between 1991 and 1994 ( N = 1,346 cases and 1,544 controls) and for the second between 1997 and 2001 ( N = 952 cases and 1,205 controls) and were asked to complete a detailed in-person interviewer-administered diet and lifestyle questionnaire. The control population is used to examine changes in screening behavior and associations with screening over time. Results. Significantly, fewer people reported fecal occult blood test (FOBT) in 1997–2001 than in 1991–1994 (62.5% in 1991–1994 vs. 47.2% in 1997–2001); a slight nonsignificant increase in sigmoidoscopy screening was reported for these periods among controls (33.9% vs. 36.6%). In the control population, during these periods, there was a statistically significant increase in the number of people who reported having had a sigmoidoscopy for screening rather than for problems (72.6% in 1997–2001 vs. 63.8% in 1991–1994). There were differences in factors associated with screening behavior by time, by sex, and by health care provider, although having a family history of colorectal cancer, having more education, and being male was associated with more screening in all settings. After adjusting for diet and lifestyle factors, we observed that non-sigmoidoscopy screening significantly influenced risk of incident cancer (rectal OR: 2.9; 95% CI, 2.3–3.7; distal tumor OR: 1.8; 95% CI, 1.4–2.3); proximal tumor: 1.4; 95% CI, 1.1–1.8). Nonuse of FOBT also was associated significantly with tumors in the rectal (OR: 1.6; 95% CI, 1.3–1.9) and distal (OR: 1.4; 95% CI, 1.1–1.8) sites. Summary. These data reinforce the importance of screening to reduce risk of colorectal cancer development. However, flexible sigmoidoscopy screening is increasing only modestly over time, and primarily in settings where a significant investment in screening has been made. FOBT screening, which is effective for rectal cancer prevention, is actually decreasing.

Screening for Colorectal Cancer

Letters18 February 2003Screening for Colorectal CancerMichael Pignone, MDMichael Pignone, MDUniversity of North Carolina; Chapel Hill, NC 27599-7110 (Pignone)Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-138-4-200302180-00023 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail IN RESPONSE:We appreciate the comments from Drs. Kirkpatrick, Budenholzer, Rosson, and Spiro. We agree with Dr. Kirkpatrick that obtaining additional data on the safety of screening colonoscopy in real-world settings is important. Resource issues, such as the capacity for performing screening colonoscopy and potential effects on the availability of the procedure for diagnostic evaluations, must also be considered (1).Dr. Budenholzer suggests that the effectiveness of colorectal cancer screening has not been demonstrated because the available randomized trials have not shown reductions in all-cause mortality. Colorectal cancer, however, accounts for fewer than 5% of all deaths, so demonstrating a ...Reference1. Rex DK, Lieberman DA. Feasibility of colonoscopy screening: discussion of issues and recommendations regarding implementation [Editorial]. Gastrointest Endosc. 2001;54:662-7. [PMID: 11677497] CrossrefMedlineGoogle Scholar Author, Article, and Disclosure InformationAffiliations: University of North Carolina; Chapel Hill, NC 27599-7110 (Pignone) PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetailsSee AlsoScreening for Colorectal Cancer in Adults at Average Risk: A Summary of the Evidence for the U.S. Preventive Services Task Force Michael Pignone , Melissa Rich , Steven M. Teutsch , Alfred O. Berg , and Kathleen N. Lohr Cost-Effectiveness Analyses of Colorectal Cancer Screening Michael Pignone , Somnath Saha , Tom Hoerger , and Jeanne Mandelblatt Screening for Colorectal Cancer Donald M. Kirkpatrick Metrics Cited byPsychotropic drugs and liver disease: A critical review of pharmacokinetics and liver toxicity 18 February 2003Volume 138, Issue 4Page: 357KeywordsCancer screeningColonoscopyColorectal cancerColorectal cancer screeningMortalityRandomized trialsSafety ePublished: 18 February 2003 Issue Published: 18 February 2003 Copyright & PermissionsCopyright © 2003 by American College of Physicians. All Rights Reserved.PDF downloadLoading ...

A national survey of primary care physicians’ colorectal cancer screening recommendations and practices

Background National data on providers’ colorectal cancer (CRC) screening knowledge, attitudes, and practices are sparse. This study assessed primary care physicians’ (PCPs’) beliefs about the effectiveness of CRC screening, their recommendations for screening, their perceptions of the influence of published guidelines on their CRC screening recommendations, and how they conduct CRC screening in their clinical practices. Methods A questionnaire was administered to a nationally representative sample of practicing PCPs. Of 1718 eligible physicians, 1235 (72%) responded. Results Only 2% of PCPs said they did not recommend CRC screening. Over 80% indicated that they most often recommend CRC screening with fecal occult blood testing and/or flexible sigmoidoscopy, although colonoscopy was perceived as the more effective screening modality. Nearly two-thirds of obstetrician/gynecologists and one-fourth of other practitioners reported conducting fecal occult blood testing exclusively by digital rectal exam. Only 29% of PCPs said they perform sigmoidoscopy. Estimated volumes of ordering, performing, or referring for CRC screening were low, and <20% reported that three-fourths or more of their older patients were up to date with CRC screening as recommended by the physician. Many PCPs reported recommending CRC screening at nonstandard starting ages or too-frequent intervals. Conclusions Awareness of CRC screening among PCPs in the United States is high. However, knowledge gaps about the timing and frequency of screening and suboptimal screening delivery were evident.

Cost effectiveness of colorectal cancer screening `open to question'

Cost effectiveness of colorectal cancer screening `open to question'

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.)

Effectiveness of colorectal cancer screening

In order to evaluate the effectiveness of colorectal cancer screening by the faecal occult blood test (FOBT) in Germany a population-based case-control study was conducted in Saarland, a southwestern state of Germany. As cases, we identified 522 persons (244 males, 278 females) who died of colorectal cancer between 1983 and 1986 between the ages of 55 and 75 years. For 163 male cases complete screening histories were retrieved together with up to five age-matched controls who had not died of colorectal cancer identified from the files of the case's referring general practitioner (GP). For 209 female cases screening histories were retrieved from their GPs and gynaecologists as well as for age-matched controls. Individual screening histories were established with emphasis on identifying whether FOBTs were carried out asymptomatically or symptomatically. In the time period 6-36 months prior to diagnosis 13% of the male cases and 14% of the male controls had at least one asymptomatic FOBT with a corresponding matched odds ratio of 0.92 (95% CI: 0.61, 1.75). For the same prediagnostic period 16% of the female cases and 29% of the female controls had at least one asymptomatic FOBT leading to an odds ratio of 0.43 (95% CI: 0.27, 0.68). Thus, for males where participation rates are generally low, no protective effect could be seen but for females where participation rates are higher a clear protective effect is seen. Possibilities for bias need to be taken into consideration when interpreting these results. Organizational measures ensuring a high penetrance of a mass screening programme are seen as a way to elevate efficacy.

Cost Effectiveness of Colorectal Cancer Screening in the Elderly

To assess the cost effectiveness of a periodic program of colorectal cancer screening in the elderly. A model was constructed of four strategies for the periodic screening of persons 65 to 85 years of age. The effect of each strategy on life expectancy and health care costs was estimated under assumptions that were uniformly unfavorable to screening. Cost and added years of life were discounted at 5% per year. Cost per year of life gained from screening was calculated for each screening strategy. Assumptions used in the model were based on a review of pertinent studies; those studies with results more unfavorable to screening were given more weight. Strengths and weaknesses of studies are discussed. A program of annual fecal occult blood testing (FOBT) in the elderly would detect at least 17% of the expected cases of cancer and could cost $35,000 per year of life saved. Screening schedules that include periodic sigmoidoscopy would prevent more cases of cancer but could cost between $43,000 and $47,000 per year of life gained. These estimates are based on uncertain assumptions, but results were not extremely sensitive to further relaxation of the values of the most uncertain assumptions. In no case did the cost per year of life gained from annual FOBT exceed $55,000 or did the cost per year of life gained from FOBT with sigmoidoscopy every 5 years exceed $61,000. Although colorectal cancer screening is costly in the aggregate, its potential medical benefits make it a reasonably cost-effective preventive intervention for the elderly.

Benefits and Harms: The Balance Sheet

To the Editor.— In his otherwise excellent article on the effectiveness of colorectal cancer screening, Dr David Eddy1makes a common but serious arithmetic error. Without screening, a high-risk 50-year-old man (like me) has about a 10.3% probability of developing colorectal cancer sometime in the rest of his life and about a 5.3% probability of dying of colorectal cancer. If such a person is screened as Dr Eddy proposes, the probabilities of developing and dying of colorectal cancer are decreased to about 7.3% and 2.9%, respectively. Thus, the effect of this screening strategy is to decrease the actual probability of developing or dying of colorectal cancer by about 3.0% and 2.4%, respectively. Dr Eddy's calculations are erroneous, and the mistake recurs throughout the article. In actuality, a decrease in the likelihood of getting cancer from 10.3% to 7.3% is a 30% improvement. When cancer mortality drops, as a result