Depth of insertion at flexible sigmoidoscopy: implications for colorectal cancer screening and instrument design

Colonoscope "Looping" During Ileo-Colonoscopy in Children is Significantly Different to that Observed in Adult Practice

OBJECTIVES

Ileo-colonoscopy (IC) can be technically challenging because of unpredictable colonoscope loop formation. Aims of this study were to assess the risk of loop formation and to attempt to understand which factors were likely to predispose to which subtype of loop.

METHODS

Prospective study conducted on children referred for an IC at Sheffield Children's Hospital. Presence and type of loop was objectively assessed using the magnetic endoscope imaging tool.

RESULTS

Three hundred procedures were prospectively evaluated. Only 9% of paediatric ICs were loop-free. Alpha loops were the most common loop in children older than 5, whereas reverse alpha loops and a wider variety of complex and repetitive loops were observed in younger patients. Once a specific type of loop has formed, the risk of re-looping in a different way or in a different position of the colon is reduced. Left lateral starting position was found to increase the risk of reverse alpha loops and re-looping. Challenging loops, such as reverse alpha, were more frequent in males. Higher body mass index (BMI) was associated with an increased risk of alpha and deep transverse loops formation, while lower BMI with a higher incidence of reverse alpha and N loop. Loop formation did not prevent 100% ileal intubation.

CONCLUSIONS

This study represents the first attempt to describe loop formation according to patient characteristics in a large paediatric series. Further studies are needed in order to establish if these findings could be helpful in simplifying the execution of IC procedures in children and facilitate the learning curve during endoscopy training programs.

Update on Flexible Sigmoidoscopy, Computed Tomographic Colonography, and Capsule Colonoscopy

This article reviews alternative colorectal cancer (CRC) screening tests, including flexible sigmoidoscopy (FS), computed tomography (CT) colonography, and colon capsule endoscopy. FS has abundant and convincing evidence supporting its use for CRC screening and is a commonly used CRC test worldwide. CT colonography has demonstrated convincing results for CRC screening, but concerns regarding cost, accuracy for flat or sessile neoplasia, reproducibility, extracolonic findings, and lack of coverage have limited its use and development. Colon capsule endoscopy has demonstrated encouraging results for polyp detection in average-risk individuals, but is not approved for CRC screening at the current time.

Cost-effectiveness of a multitarget stool DNA test for colorectal cancer screening of Medicare beneficiaries

BACKGROUND

In 2014, the Centers for Medicare and Medicaid Services (CMS) began covering a multitarget stool DNA (mtSDNA) test for colorectal cancer (CRC) screening of Medicare beneficiaries. In this study, we evaluated whether mtSDNA testing is a cost-effective alternative to other CRC screening strategies reimbursed by CMS, and if not, under what conditions it could be.

METHODS

We use three independently-developed microsimulation models to simulate a cohort of previously unscreened US 65-year-olds who are screened with triennial mtSDNA testing, or one of six other reimbursed screening strategies. Main outcome measures are discounted life-years gained (LYG) and lifetime costs (CMS perspective), threshold reimbursement rates, and threshold adherence rates. Outcomes are expressed as the median and range across models.

RESULTS

Compared to no screening, triennial mtSDNA screening resulted in 82 (range: 79-88) LYG per 1,000 simulated individuals. This was more than for five-yearly sigmoidoscopy (80 (range: 71-89) LYG), but fewer than for every other simulated strategy. At its 2017 reimbursement rate of $512, mtSDNA was the most costly strategy, and even if adherence were 30% higher than with other strategies, it would not be a cost-effective alternative. At a substantially reduced reimbursement rate ($6-18), two models found that triennial mtSDNA testing was an efficient and potentially cost-effective screening option.

CONCLUSIONS

Compared to no screening, triennial mtSDNA screening reduces CRC incidence and mortality at acceptable costs. However, compared to nearly all other CRC screening strategies reimbursed by CMS it is less effective and considerably more costly, making it an inefficient screening option.

Early Detection for Colorectal Cancer: ASCO Resource-Stratified Guideline

PURPOSE

To provide resource-stratified, evidence-based recommendations on the early detection of colorectal cancer in four tiers to clinicians, patients, and caregivers.

METHODS

American Society of Clinical Oncology convened a multidisciplinary, multinational panel of medical oncology, surgical oncology, surgery, gastroenterology, health technology assessment, cancer epidemiology, pathology, radiology, radiation oncology, and patient advocacy experts. The Expert Panel reviewed existing guidelines and conducted a modified ADAPTE process and a formal consensus-based process with additional experts (Consensus Ratings Group) for two round(s) of formal ratings.

RESULTS

Existing sets of guidelines from eight guideline developers were identified and reviewed; adapted recommendations form the evidence base. These guidelines, along with cost-effectiveness analyses, provided evidence to inform the formal consensus process, which resulted in agreement of 75% or more.

CONCLUSION

In nonmaximal settings, for people who are asymptomatic, are ages 50 to 75 years, have no family history of colorectal cancer, are at average risk, and are in settings with high incidences of colorectal cancer, the following screening options are recommended: guaiac fecal occult blood test and fecal immunochemical testing (basic), flexible sigmoidoscopy (add option in limited), and colonoscopy (add option in enhanced). Optimal reflex testing strategy for persons with positive screens is as follows: endoscopy; if not available, barium enema (basic or limited). Management of polyps in enhanced is as follows: colonoscopy, polypectomy; if not suitable, then surgical resection. For workup and diagnosis of people with symptoms, physical exam with digital rectal examination, double contrast barium enema (only in basic and limited); colonoscopy; flexible sigmoidoscopy with biopsy (if contraindication to latter) or computed tomography colonography if contraindications to two endoscopies (enhanced only).

Whole-colon investigation vs. flexible sigmoidoscopy for suspected colorectal cancer based on presenting symptoms and signs: a multicentre cohort study

BACKGROUND

Patients with suspected colorectal cancer (CRC) usually undergo colonoscopy. Flexible sigmoidoscopy (FS) may be preferred if proximal cancer risk is low. We investigated which patients could undergo FS alone.

METHODS

Cohort study of 7375 patients (≥55 years) referred with suspected CRC to 21 English hospitals (2004-2007), followed using hospital records and cancer registries. We calculated yields and number of needed whole-colon examinations (NNE) to diagnose one cancer by symptoms/signs and subsite. We considered narrow (haemoglobin <11 g/dL men; <10 g/dL women) and broad (<13 g/dL men; <12 g/dL women) anaemia definitions and iron-deficiency anaemia (IDA).

RESULTS

One hundred and twenty-seven proximal and 429 distal CRCs were diagnosed. A broad anaemia definition identified 80% of proximal cancers; a narrow definition with IDA identified 39%. In patients with broad definition anaemia and/or abdominal mass, proximal cancer yield and NNE were 4.8% (97/2022) and 21. In patients without broad definition anaemia and/or abdominal mass, with rectal bleeding or increased stool frequency (41% of cohort), proximal cancer yield and NNE were 0.4% (13/3031) and 234.

CONCLUSION

Most proximal cancers are accompanied by broad definition anaemia. In patients without broad definition anaemia and/or abdominal mass, with rectal bleeding or increased stool frequency, proximal cancer is rare and FS should suffice.

Anatomical distribution and detection rate of colorectal neoplasms according to age in the colonoscopic screening of a Korean population

Purpose

Because data as a basis for the determination of proper age and modality for screening of colorectal neoplasms is lacking, we evaluated detection rates and anatomical distribution of colorectal neoplasms according to age in healthy individuals who underwent total colonoscopy for health checkup.

Methods

A total of 16,100 cases that had received the colonoscopic examination from January to December in 2014 were analyzed. The total number of individuals who received total colonoscopy were divided by the number of individuals harboring colorectal adenoma to calculate the detection rate of colorectal adenoma. Individuals ≤50 years old were classified as young-age group and aged >50 were old-age group. Differences in anatomical locations of colorectal neoplasms were analyzed in the 2 age groups by chi-square test. Risk factors for colorectal adenoma in each age group were analyzed using univariate and multivariate logistic regression analyses.

Results

Detection rates of colorectal adenoma were 13.7% in all cases and 12.8% for those in their 40's. The main anatomical location of colorectal adenoma was proximal colon in both age groups (P < 0.001). Hyperplastic polyp was mainly distributed to the distal colon in both age groups (P < 0.001). Distal colon was the major site for colorectal cancer in the old-age group (P = 0.001). Proximal location of neoplasms was a risk factor for colorectal adenoma in both age groups with multivariate analysis.

Conclusion

These data could be the bases for earlier initiation of screening for colorectal neoplasms with total colonoscopy to detect clinically significant colorectal polyps.

Is whole-colon investigation by colonoscopy, computerised tomography colonography or barium enema necessary for all patients with colorectal cancer symptoms, and for which patients would flexible sigmoidoscopy suffice? A retrospective cohort study

BACKGROUND

For patients referred to hospital with suspected colorectal cancer (CRC), it is current standard clinical practice to conduct an examination of the whole colon and rectum. However, studies have shown that an examination of the distal colorectum using flexible sigmoidoscopy (FS) can be a safe and clinically effective investigation for some patients. These findings require validation in a multicentre study.

OBJECTIVES

To investigate the links between patient symptoms at presentation and CRC risk by subsite, and to provide evidence of whether or not FS is an effective alternative to whole-colon investigation (WCI) in patients whose symptoms do not suggest proximal or obstructive disease.

DESIGN

A multicentre retrospective study using data collected prospectively from two randomised controlled trials. Additional data were collected from trial diagnostic procedure reports and hospital records. CRC diagnoses within 3 years of referral were sourced from hospital records and national cancer registries via the Health and Social Care Information Centre.

SETTING

Participants were recruited to the two randomised controlled trials from 21 NHS hospitals in England between 2004 and 2007.

PARTICIPANTS

Men and women aged ≥ 55 years referred to secondary care for the investigation of symptoms suggestive of CRC.

MAIN OUTCOME MEASURE

Diagnostic yield of CRC at distal (to the splenic flexure) and proximal subsites by symptoms/clinical signs at presentation.

RESULTS

The data set for analysis comprised 7380 patients, of whom 59% were women (median age 69 years, interquartile range 62-76 years). Change in bowel habit (CIBH) was the most frequently presenting symptom (73%), followed by rectal bleeding (38%) and abdominal pain (29%); 26% of patients had anaemia. CRC was diagnosed in 551 patients (7.5%): 424 (77%) patients with distal CRC, 122 (22%) patients with cancer proximal to the descending colon and five patients with both proximal and distal CRC. Proximal cancer was diagnosed in 96 out of 2021 (4.8%) patients with anaemia and/or an abdominal mass. The yield of proximal cancer in patients without anaemia or an abdominal mass who presented with rectal bleeding with or without a CIBH or with a CIBH to looser and/or more frequent stools as a single symptom was low (0.5%). These low-risk groups for proximal cancer accounted for 41% (3032/7380) of the cohort; only three proximal cancers were diagnosed in 814 low-risk patients examined by FS (diagnostic yield 0.4%).

LIMITATIONS

A limitation to this study is that changes to practice since the trial ended, such as new referral guidelines and improvements in endoscopy quality, potentially weaken the generalisability of our findings.

CONCLUSIONS

Symptom profiles can be used to determine whether or not WCI is necessary. Most proximal cancers were diagnosed in patients who presented with anaemia and/or an abdominal mass. In patients without anaemia or an abdominal mass, proximal cancer diagnoses were rare in those with rectal bleeding with or without a CIBH or with a CIBH to looser and/or more frequent stools as a single symptom. FS alone should be a safe and clinically effective investigation in these patients. A cost-effectiveness analysis of symptom-based tailoring of diagnostic investigations for CRC is recommended.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN95152621.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 66. See the NIHR Journals Library website for further project information.

Validation of Models Used to Inform Colorectal Cancer Screening Guidelines: Accuracy and Implications

BACKGROUND

Microsimulation models synthesize evidence about disease processes and interventions, providing a method for predicting long-term benefits and harms of prevention, screening, and treatment strategies. Because models often require assumptions about unobservable processes, assessing a model's predictive accuracy is important.

METHODS

We validated 3 colorectal cancer (CRC) microsimulation models against outcomes from the United Kingdom Flexible Sigmoidoscopy Screening (UKFSS) Trial, a randomized controlled trial that examined the effectiveness of one-time flexible sigmoidoscopy screening to reduce CRC mortality. The models incorporate different assumptions about the time from adenoma initiation to development of preclinical and symptomatic CRC. Analyses compare model predictions to study estimates across a range of outcomes to provide insight into the accuracy of model assumptions.

RESULTS

All 3 models accurately predicted the relative reduction in CRC mortality 10 years after screening (predicted hazard ratios, with 95% percentile intervals: 0.56 [0.44, 0.71], 0.63 [0.51, 0.75], 0.68 [0.53, 0.83]; estimated with 95% confidence interval: 0.56 [0.45, 0.69]). Two models with longer average preclinical duration accurately predicted the relative reduction in 10-year CRC incidence. Two models with longer mean sojourn time accurately predicted the number of screen-detected cancers. All 3 models predicted too many proximal adenomas among patients referred to colonoscopy.

CONCLUSION

Model accuracy can only be established through external validation. Analyses such as these are therefore essential for any decision model. Results supported the assumptions that the average time from adenoma initiation to development of preclinical cancer is long (up to 25 years), and mean sojourn time is close to 4 years, suggesting the window for early detection and intervention by screening is relatively long. Variation in dwell time remains uncertain and could have important clinical and policy implications.

Estimation of Benefits, Burden, and Harms of Colorectal Cancer Screening Strategies: Modeling Study for the US Preventive Services Task Force

IMPORTANCE

The US Preventive Services Task Force (USPSTF) is updating its 2008 colorectal cancer (CRC) screening recommendations.

OBJECTIVE

To inform the USPSTF by modeling the benefits, burden, and harms of CRC screening strategies; estimating the optimal ages to begin and end screening; and identifying a set of model-recommendable strategies that provide similar life-years gained (LYG) and a comparable balance between LYG and screening burden.

DESIGN, SETTING, AND PARTICIPANTS

Comparative modeling with 3 microsimulation models of a hypothetical cohort of previously unscreened US 40-year-olds with no prior CRC diagnosis.

EXPOSURES

Screening with sensitive guaiac-based fecal occult blood testing, fecal immunochemical testing (FIT), multitarget stool DNA testing, flexible sigmoidoscopy with or without stool testing, computed tomographic colonography (CTC), or colonoscopy starting at age 45, 50, or 55 years and ending at age 75, 80, or 85 years. Screening intervals varied by modality. Full adherence for all strategies was assumed.

MAIN OUTCOMES AND MEASURES

Life-years gained compared with no screening (benefit), lifetime number of colonoscopies required (burden), lifetime number of colonoscopy complications (harms), and ratios of incremental burden and benefit (efficiency ratios) per 1000 40-year-olds.

RESULTS

The screening strategies provided LYG in the range of 152 to 313 per 1000 40-year-olds. Lifetime colonoscopy burden per 1000 persons ranged from fewer than 900 (FIT every 3 years from ages 55-75 years) to more than 7500 (colonoscopy screening every 5 years from ages 45-85 years). Harm from screening was at most 23 complications per 1000 persons screened. Strategies with screening beginning at age 50 years generally provided more LYG as well as more additional LYG per additional colonoscopy than strategies with screening beginning at age 55 years. There were limited empirical data to support a start age of 45 years. For persons adequately screened up to age 75 years, additional screening yielded small increases in LYG relative to the increase in colonoscopy burden. With screening from ages 50 to 75 years, 4 strategies yielded a comparable balance of screening burden and similar LYG (median LYG per 1000 across the models): colonoscopy every 10 years (270 LYG); sigmoidoscopy every 10 years with annual FIT (256 LYG); CTC every 5 years (248 LYG); and annual FIT (244 LYG).

CONCLUSIONS AND RELEVANCE

In this microsimulation modeling study of a previously unscreened population undergoing CRC screening that assumed 100% adherence, the strategies of colonoscopy every 10 years, annual FIT, sigmoidoscopy every 10 years with annual FIT, and CTC every 5 years performed from ages 50 through 75 years provided similar LYG and a comparable balance of benefit and screening burden.

Should colorectal cancer screening be considered in elderly persons without previous screening? A cost-effectiveness analysis

BACKGROUND

The U.S. Preventive Services Task Force recommends against routine screening for colorectal cancer (CRC) in adequately screened persons older than 75 years but does not address the appropriateness of screening in elderly persons without previous screening.

OBJECTIVE

To determine at what ages CRC screening should be considered in unscreened elderly persons and to determine which test is indicated at each age.

DESIGN

Microsimulation modeling study.

DATA SOURCES

Observational and experimental studies.

TARGET POPULATION

Unscreened persons aged 76 to 90 years with no, moderate, and severe comorbid conditions.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTION

One-time colonoscopy, sigmoidoscopy, or fecal immunochemical test (FIT) screening.

OUTCOME MEASURES

Quality-adjusted life-years gained, costs, and costs per quality-adjusted life-year gained.

RESULTS OF BASE-CASE ANALYSIS

In unscreened elderly persons with no comorbid conditions, CRC screening was cost-effective up to age 86 years. Screening with colonoscopy was indicated up to age 83 years, sigmoidoscopy was indicated at age 84 years, and FIT was indicated at ages 85 and 86 years. In unscreened persons with moderate comorbid conditions, screening was cost-effective up to age 83 years (colonoscopy indicated up to age 80 years, sigmoidoscopy at age 81 years, and FIT at ages 82 and 83 years). In unscreened persons with severe comorbid conditions, screening was cost-effective up to age 80 years (colonoscopy indicated up to age 77 years, sigmoidoscopy at age 78 years, and FIT at ages 79 and 80 years).

RESULTS OF SENSITIVITY ANALYSES

Results were most sensitive to assuming a lower willingness to pay per quality-adjusted life-year gained.

LIMITATION

Only persons at average risk for CRC were considered.

CONCLUSION

In unscreened elderly persons CRC screening should be considered well beyond age 75 years. A colonoscopy is indicated at most ages.

PRIMARY FUNDING SOURCE

National Cancer Institute.

A birth cohort analysis of the incidence of ascending and descending colon cancer in the United States, 1973-2008

OBJECTIVES

There is evidence indicating that the trends in colorectal cancer (CRC) incidence rates in the United States differ according to CRC subsites, including for ascending cancer which has shown a different pattern from the overall trends. We investigated the time trends for ascending and descending colon cancer in the United States by race and gender to identify the specific components that may account for the incidence trends.

METHODS

Using data from the National Cancer Institute's Surveillance, Epidemiology, and End Results program for 1973-2008, we conducted age-period-cohort modeling to evaluate birth cohort patterns and evaluate age-period-cohort effects on incidence trends of colon cancer over time.

RESULTS

A clear birth cohort pattern was observed for both ascending and descending colon cancer, and the incidence rates of ascending colon cancer in the more recent birth cohorts were higher compared to earlier cohorts particularly for black males and females. This increase was most obvious in the younger age groups and appeared to accelerate, especially for black females. For descending colon cancer, the study suggested an increase in the birth cohort slope in the later birth cohorts for all gender and race groups, after a period of decline in earlier birth cohorts.

CONCLUSION

The increase in incidence rates of both ascending and descending colon cancer in more recent birth cohorts for blacks suggests the need for targeted public health strategies to increase CRC screening. Further, additional etiological studies are warranted to evaluate factors responsible for the observed trends in more recent birth cohorts, including differences by subsites, race, and/or gender.

Risk stratification for advanced proximal colon neoplasm and individualized endoscopic screening for colorectal cancer by a risk-scoring model

BACKGROUND

Only 30% to 40% of patients with advanced proximal neoplasms (APN) have distal colon neoplasms.

OBJECTIVE

To develop a risk score model for APN and propose an individualized screening protocol for colorectal cancer.

DESIGN

Retrospective cohort study.

SETTING

Tertiary-care center.

PATIENTS

Derivation cohort (6200 adults) and validation cohort (1389 adults).

INTERVENTION

Screening colonoscopy.

MAIN OUTCOME MEASUREMENTS

An APN risk score model was developed from the derivation cohort (6200 adults) and was tested in the validation cohort (1389 adults), who underwent screening colonoscopy.

RESULTS

Age, male sex, and smoking were clinical risk factors for APN. The presence of a distal neoplasm was a sigmoidoscopic risk factor for APN. We calculated APN risk scores (0-8) based on these variables and classified patients as low risk (0-2) or high risk (3-8). In the validation cohort, the relative risk of APN was 3.5-fold higher in the high-risk group than in the low-risk group. Our model suggests that colonoscopy should be performed as an initial screening test in patients with a high clinical risk for APN. Sigmoidoscopy should be performed initially in patients with low clinical risk for APN followed by supplementary colonoscopy in those with high APN risk scores based on both clinical and sigmoidoscopic risk factors. This protocol detected APN in 22 of 34 APN+ patients (64.7%) with little increase in the endoscopy burden, whereas only 16 of 34 APN+ patients (47.1%) would be identified by initial sigmoidoscopy followed by colonoscopy only in cases with distal neoplasms.

LIMITATIONS

Retrospective design.

CONCLUSION

Our APN risk score model provides an algorithm for efficient screening of colorectal cancer by sigmoidoscopy and colonoscopy.

Concerns and challenges in flexible sigmoidoscopy screening

In 1992, two well-conducted case-control studies used data from two different health maintenance organizations and demonstrated a 59-79% reduction in mortality from colorectal cancer (CRC) following exposure to sigmoidoscopy. These studies highlight the possibility of reducing mortality from CRC using population-based endoscopic screening. The development of fiber optics improved the technology, and the ease of performing flexible sigmoidoscopy (FS) with widespread adoption of this screening modality. To date, FS is the only endoscopic screening modality that has been shown to reduce mortality in randomized clinical trials. This article reviews the development of sigmoidoscopy, its use in CRC screening and the current reduced role of this proven screening modality, and explores new frontiers for population-based FS screening.

The relationship between distal and proximal colonic neoplasia: a meta-analysis

OBJECTIVES

To investigate the association between proximal colonic neoplasia and distal lesions as a function of the lesion type. The extent to which health, demographic, and study characteristics moderate this association was also examined.

DATA SOURCES

Google Scholar, Web of Science, Scopus, and PubMed.

STUDY ELIGIBILITY CRITERIA

Studies allowing the calculation of OR of proximal neoplasia (PN) and proximal advanced neoplasia (PAN) for distal hyperplastic polyps (HP), nonadvanced adenomas (NAA), adenomas (AD), and advanced neoplasia (AN); also, studies for which the proportions of subjects with isolated (i.e., not accompanied by distal lesions) PN (IPN) and PAN (IPAN) over the total number of subjects with PN or PAN could be calculated.

STUDY APPRAISAL AND SYNTHESIS METHODS

Thirty-two studies were included for calculating OR between proximal neoplasia and distal lesions and 40 studies for proportions of IPN and IPAN. Subgroup analyses were conducted for presence of symptoms, prevalence of PN and PAN, age, proportion of males, geographic region, study design, and demarcation point.

RESULTS

The association between distal lesions and proximal neoplasia increased with the severity of the distal lesions. Odds of PN were higher in subjects with HP compared to subjects with a normal distal colon. Odds of PN and PAN were higher in subjects with NAA, AD, and AN than in subjects with a normal distal colon. PAN were more strongly associated with distal lesions in asymptomatic populations, in young populations, and in populations with a low prevalence of PAN. In approximately 60% of the subjects with PN and PAN, these neoplasia were isolated.

LIMITATIONS

The present results may be affected by publication bias and dichotomization in the subgroup analyses. Limitations related to the individual studies include self-selection, lesion misclassification and misses, and technological advances leading to changes in the detection of lesions during the time span of the included studies.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

All types of distal lesions are predictive of PN. All types of distal neoplasia are predictive of PAN. The association between distal lesions and proximal neoplasia increases with the severity of the distal lesion. The association between distal lesions and proximal advanced neoplasia is stronger in low-risk groups as compared to high-risk groups.

Editorial: risk scoring for colon cancer screening: validated, but still not ready for prime time

Risk stratification for colorectal cancer screening would allow us to use less expensive screening tests, such as sigmoidoscopy with or without fecal blood testing, on lower risk individuals, and reserve colonoscopy for those at higher risk. In this issue, Levitzky et al. validates a risk score that was previously developed by Imperiale et al., finding similar results among three ethnic groups. Risk scoring would detect 82-87% of proximal advanced neoplasia while decreasing colonoscopy use by 33-46%. However, before risk scoring is ready for widespread use, sigmoidoscopy access and performance issues need to be addressed, and we must be comfortable with missing some proximal neoplasms.

Colorectal cancer screening for average-risk North Americans: an economic evaluation

BACKGROUND

Colorectal cancer (CRC) fulfills the World Health Organization criteria for mass screening, but screening uptake is low in most countries. CRC screening is resource intensive, and it is unclear if an optimal strategy exists. The objective of this study was to perform an economic evaluation of CRC screening in average risk North American individuals considering all relevant screening modalities and current CRC treatment costs.

METHODS AND FINDINGS

An incremental cost-utility analysis using a Markov model was performed comparing guaiac-based fecal occult blood test (FOBT) or fecal immunochemical test (FIT) annually, fecal DNA every 3 years, flexible sigmoidoscopy or computed tomographic colonography every 5 years, and colonoscopy every 10 years. All strategies were also compared to a no screening natural history arm. Given that different FIT assays and collection methods have been previously tested, three distinct FIT testing strategies were considered, on the basis of studies that have reported "low," "mid," and "high" test performance characteristics for detecting adenomas and CRC. Adenoma and CRC prevalence rates were based on a recent systematic review whereas screening adherence, test performance, and CRC treatment costs were based on publicly available data. The outcome measures included lifetime costs, number of cancers, cancer-related deaths, quality-adjusted life-years gained, and incremental cost-utility ratios. Sensitivity and scenario analyses were performed. Annual FIT, assuming mid-range testing characteristics, was more effective and less costly compared to all strategies (including no screening) except FIT-high. Among the lifetimes of 100,000 average-risk patients, the number of cancers could be reduced from 4,857 to 1,393 [corrected] and the number of CRC deaths from 1,782 [corrected] to 457, while saving CAN$68 per person. Although screening patients with FIT became more expensive than a strategy of no screening when the test performance of FIT was reduced, or the cost of managing CRC was lowered (e.g., for jurisdictions that do not fund expensive biologic chemotherapeutic regimens), CRC screening with FIT remained economically attractive.

CONCLUSIONS

CRC screening with FIT reduces the risk of CRC and CRC-related deaths, and lowers health care costs in comparison to no screening and to other existing screening strategies. Health policy decision makers should consider prioritizing funding for CRC screening using FIT.

Prevalence and risk of colorectal adenoma in asymptomatic Koreans aged 40-49 years undergoing screening colonoscopy

BACKGROUND AND AIM

Colorectal cancer screening is recommended for average-risk persons beginning at age 50. However, information about the incidence and risk factors of precursor adenoma in preceding decades is limited. The aim of this study was to determine the prevalence and risk factors of colorectal adenoma in persons aged 40-49 years and to compare the data with those aged 30-39 years and 50-59 years.

METHODS

A cross-sectional study of 5254 asymptomatic subjects who underwent screening colonoscopy was conducted. Data were stratified by age into three groups: 608 aged 30-39 years, 1930 aged 40-49 years, and 2716 aged 50-59 years.

RESULTS

Prevalence of overall adenomas was 10.4% in the 30-39 years age group, 22.2% in the 40-49 years age group, and 32.8% in the 50-59 years age group. Advanced adenoma was found in 0.7% of the 30-39 years age group, 2.7% of the 40-49 years age group, and 4.1% of the 50-59 years age group. In the 40-49 years age group, male sex and current smoking habits showed associations with low-risk adenoma after multiple adjustments. Moreover, male sex (odds ratio [OR] = 1.55, 95% confidence interval [CI]: 1.02-3.23), current smoking (OR = 1.58, 95%CI: 1.06-3.50), and family history of colorectal cancer (OR = 2.54, 95%CI: 1.16-5.56) were independent predictors of advanced adenoma in this age group.

CONCLUSIONS

Prevalence of adenoma in subjects aged 40-49 years was higher than in previous studies. Male sex and current smoking habits along with a family history of colorectal cancer were associated with advanced adenoma in this age group.

Screening for colorectal cancer

Colorectal cancer (CRC) is the most common cancer in the Nordic countries after breast and prostate cancer. About 15,000 new cancers are diagnosed and more than 7000 patients will die from CRC in 2005. CRC fulfils most of the criteria for applying screening; the natural history is well known compared with many other cancers. CRC may be cured by detection at an early stage and even prevented by removal of possible precursors like adenomas. Faecal occult blood test is the only CRC screening modality that has been subjected to adequately sized randomised controlled trials (RCT) with long-term follow-up results, using Hemoccult-II. Sensitivity for strictly asymptomatic CRC is less than 30% for a single screening round, but programme sensitivity has been estimated to be more. Biennial screening with un-rehydrated Hemoccult-II slides has shown a CRC mortality reduction of 15-18% after approximately 10 years of follow-up in those targeted for screening. For those attending, the mortality reduction has been estimated at 23%. Denmark has decided to do feasibility studies to try to evaluate whether a population-based screening run by the community will have the same effect as has been demonstrated in the randomised trials. In Norway the government has accepted no formal population-based screening. In Finland, the Ministry of Social Affairs and Health made a recommendation in 2003 to the municipalities to run a randomised feasibility study with FOBT screening for colorectal cancer as a public health policy that is repeated every second year. In 2004 the first municipalities started. It has been claimed that today Sweden cannot afford CRC screening despite the potential mortality benefit. There is sufficient evidence for the efficacy of screening for colorectal cancer with fecal occult blood test every second year. There is, however, only little evidence on the effectiveness of screening when run as a public health service and there is insufficient knowledge of harmful effects and costs, even in RCTs.

Colosigmoid junction: morphohistologic, morphometric, and endoscopic study with identification of colosigmoid canal with sphincter

To study the anatomical structure of the colosigmoid junction, 15 cadaveric specimens were studied morphologically, another 15 histologically, and a morphometric study was done in 10 specimens. Specimens consisted of the descending colon, sigmoid colon, and the colosigmoid junction. Histologic specimens were stained with hematoxylin and eosin and Masson's trichrome stain. Morphometric studies used an image analysis system. The colosigmoid junction was investigated endoscopically in 18 healthy volunteers. A narrow segment having a mean length of 5.2 +/- 1.1 cm was identified both externally and internally between the descending and sigmoid colon. We called this segment the colosigmoid canal. Mucosal folds were found crowded in the colosigmoid canal, the lower end of which formed a nipple and was surrounded by a fornix. Histologically, the colosigmoid canal mucosa showed multiple folds. Its circular muscle was thicker than that of the descending or the sigmoid colon and confirmed morphometrically. The longitudinal muscle was thicker in only 4 of 10 specimens. Both the narrowing and the mucosal crowding were verified endoscopically. The colosigmoid junction is the narrow segment between the descending and the sigmoid colon. Histologic, morphometric and endoscopic studies indicated the presence of a sphincter in the colosigmoid canal. A colosigmoid sphincter is suggested to control the passage of colonic contents from the descending colon to the colosigmoid canal as well as to prevent reflux of sigmoid contents into the descending colon.

Distribution of colon neoplasia in Chinese patients: implications for endoscopic screening strategies

OBJECTIVES

Our aim was to measure the prevalence and distribution of colonic neoplasia in Chinese adults, and to estimate the sensitivity of sigmoidoscopic screening strategies for detecting those with advanced neoplasia.

METHODS

Asymptomatic, average-risk Chinese adults aged 50 years or older underwent screening colonoscopy. The prevalence and distribution of colonic neoplasia and advanced neoplasia (defined as an adenoma >or=10 mm or with villous, high-grade dysplastic, or malignant features) were reviewed retrospectively and the outcomes of various sigmoidoscopic screening strategies estimated.

RESULTS

Of 1,382 individuals (833 men, 549 women; mean age 58.8 years) included, 243 (18%) had colorectal neoplasia and 72 (5.2%) had advanced neoplasia. Neoplasia prevalence was significantly higher in male and older patients. No significant differences were observed in neoplasia distribution between men and women. Overall, 24 patients had advanced neoplasia in the proximal colon, of whom four had synchronous distal neoplasia. The estimated sensitivity for detecting patients with advanced neoplasia was 72% if we assumed screening sigmoidoscopy was performed, with follow-up colonoscopy for those with distal neoplasia; 165 patients would need to undergo colonoscopy. If, instead, we assumed follow-up colonoscopy was done only for patients with distal advanced neoplasia, the estimated sensitivity would decrease slightly to 71%, but the number of colonoscopies would decrease substantially to 51.

CONCLUSION

In average-risk Chinese adults, screening sigmoidoscopy is estimated to detect more than two-thirds of patients with advanced neoplasia. In Chinese societies with limited health-care resources, performing colonoscopy only on patients with distal advanced neoplasia is a screening approach that optimizes the return rate on colonoscopic capacity.

Ethical aspects of capsule endoscopy

Capsule endoscopy is the most recent innovation in gastrointestinal endoscopy. The capsule contains a video camera that photographs the bowel for 8 h after the capsule has been orally ingested and transmits the images for interpretation to a computerized workstation. Ethical considerations of the use of capsule endoscopy should cover the following main issues: justification of the procedure, its potential benefits and harm, and patient autonomy. Capsule endoscopy has several advantages over traditional endoscopy. The procedure is painless, does not require sedation, is easy to perform and for the first time enables exploration of the entire small bowel at high magnification. However, the clinician cannot control its passive advance along the bowel. In addition, the examination may be incomplete, as the capsule reaches the cecum in only 80% of cases. This paper discusses the problems related to the new endoscopic procedure, the diagnostic yield in comparison with other procedures, proper indications for the procedure, outcome and complications.

Comfort and efficacy of a longer and thinner endoscope for average risk colon cancer screening

The aim of this prospective study was to assess patient comfort during nonsedated screening sigmoidoscopy with the use of a standard 60-cm sigmoidoscope compared with a thinner 100-cm upper endoscope. Patients undergoing routine colon cancer screening with sigmoidoscopy were randomly assigned to either a 60-cm sigmoidoscope or a 100-cm upper endoscope. The procedure time, depth of insertion, anatomic landmarks, and presence of polyps were documented. Likert 7-point scales and visual analog scales (VAS) were performed to measure comfort and symptoms immediately after the procedure and again in 1 week. These scales, procedure time, insertion depth, percent reaching transverse colon, and percent with polyps were analyzed. Eighty-one patients were enrolled with 38 in the 100-cm group and 43 in the 60-cm group. Patients in the 100-cm group reported greater comfort on the VAS compared with the 60-cm group (P = .035) as well as less cramping on the initial Likert scale (P = .017). One week later, the 100-cm group reported higher comfort (P = .015) and less bloating (P = .040). Procedure time was longer for the 100-cm group (8.8 versus 5.9 minutes; P = .001). Insertion depth was 74 versus 56 cm (P = .001), and percent reaching splenic flexure was 76% versus 35% (P = .001) in the 100 and 60 cm groups, respectively. More adenomas were found with the 100-cm scope (P = .035). The use of a thinner and longer endoscope is more comfortable than a standard sigmoidoscope. Although a 100-cm endoscope procedure takes longer to perform, it allows better evaluation of the colon and misses fewer adenomas.

Potential for Colorectal Cancer Prevention of Sigmoidoscopy Versus Colonoscopy: Population-Based Case Control Study

We aimed to estimate the proportions of colorectal cancer cases that might be prevented by sigmoidoscopy compared with colonoscopy among women and men. In a population-based case control study conducted in Germany, 540 cases with a first diagnosis of primary colorectal cancer and 614 controls matched for age, sex, and county of residence were recruited. A detailed lifetime history of endoscopic examinations of the large bowel was obtained by standardized personal interviews, validated by medical records, and compared between cases and controls, paying particular attention to location of colorectal cancer and sex differences. Overall, 39%, 77%, and 64% of proximal, distal, and total colorectal cancer cases were estimated to be preventable by colonoscopy. The estimated proportion of total colorectal cancer cases preventable by sigmoidoscopy was 45% among both women and men, assuming that sigmoidoscopy reaches the junction of the descending and sigmoid colon only and findings of distal polyps are not followed by colonoscopy. Assuming that sigmoidoscopy reaches the splenic flexure and colonoscopy is done after detection of distal polyps, estimated proportions of total colorectal cancer preventable by sigmoidoscopy increase to 50% and 55% (73% and 91% of total colorectal cancer preventable by primary colonoscopy) among women and men, respectively. We conclude that colonoscopy provides strong protection against colorectal cancer among both women and men. The proportion of this protection achieved by sigmoidoscopy with follow-up colonoscopy in case of distal polyps may be larger than anticipated. Among men, this regimen may be almost as effective as colonoscopy, at least at previous performance levels of colonoscopy.

Secular changes in colorectal cancer incidence by subsite, stage at diagnosis, and race/ethnicity, 1992-2001

BACKGROUND

Cancers of the colon and rectum are the third most common malignancy among males and females in the United States, although incidence and mortality have declined in recent years. We evaluated recent trends in colorectal cancer incidence in the United States by subsite and stage at diagnosis.

METHODS

Data for this analysis included all cases of colorectal cancer diagnosed between 1992 and 2001 and reported to the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program. Incidence rates were stratified by gender, race/ethnicity, anatomic subsite, stage at diagnosis, and SEER registry. Trends in incidence over time were measured using the estimated annual percentage change.

RESULTS

The study population included 95,539 males and 93,329 females with colorectal cancer. For all 12 SEER registries combined, incidence declined between 1992 and 2001 by 1.2% per year among males and 0.7% per year (not statistically significant) among females. Rates for non-Hispanic whites declined by an average of 1.3% per year for males and 0.6% per year for females. Overall rates for black, Asian/Pacific Islander, and Hispanic males and females did not change significantly except for a 0.8% decline among Asian/Pacific Islander males. Declines in rates among males and females were most pronounced for tumors of the sigmoid colon.

CONCLUSIONS

Colorectal cancer rates decreased in the United States during the 1990s. Decreases were most pronounced among males, among non-Hispanic whites, and for tumors of the sigmoid colon. These reductions are probably dueto the increased use of screening.

Incomplete screening flexible sigmoidoscopy associated with female sex, age, and increased risk of colorectal cancer

BACKGROUND

Several previous studies have found that females and older individuals are at greater risk of having incomplete flexible sigmoidoscopy. However, no prior study has reported the subsequent risk of colorectal cancer (CRC) following incomplete sigmoidoscopy.

METHODS

Using data from 55 791 individuals screened as part of the Colon Cancer Prevention (CoCaP) programme of Kaiser Permanente of Northern California, we evaluated the likelihood of having an inadequate (<40 cm) examination by age and sex, and estimated the risk of distal CRC according to depth of sigmoidoscope insertion at the baseline screening examination. Multivariate estimation of risks was performed using Poisson regression.

RESULTS

Older individuals were at a much greater risk of having an inadequate examination (relative risk (RR) for age 80+ years compared with 50-59 years 2.6 (95% confidence interval (CI) 2.3-3.0)), as were females (RR 2.3 (95% CI 2.2-2.5)); these associations were attenuated but remained strong if Poisson models were further adjusted for examination limitations (pain, stool, and angulation). There was an approximate threefold increase in the risk of distal CRC if the baseline sigmoidoscopy did not reach a depth of at least 40 cm; a smaller increase in risk was observed for examinations that reached 40-59 cm.

CONCLUSIONS

Older individuals and women are at an increased risk of having inadequate sigmoidoscopy. Because inadequate sigmoidoscopy results in an increased risk of subsequent CRC, physicians should consider steps to maximise the depth of insertion of the sigmoidoscope or, failing this, should consider an alternative screening test.

Changing patterns of colorectal cancer in China over a period of 20 years

AIM: To determine whether any changes have occurred on the patterns of colorectal cancer in China.

METHODS: Data from 21 Chinese articles published from 1980 to 1999, were used to analyze the time trend of colorectal cancer according to the patients’ age at diagnosis, sex, the site of the tumor, stage, and the pathology.

RESULTS: From 1980s to 1990s, the mean age of the colorectal cancer patients has increased. The percentage of the female patients rose. The distribution of colorectal carcinoma shows a predominance of rectal cancer. However, the proportion of proximal colon cancer (including transverse and ascending colon) increased significantly accompanied by a decline in the percentage of rectal cancer. Similarity in the percentage of distal colon cancer between two decades was revealed. In the 1990s, statistically more Stage B patients were found than those in 1980s. In addition, databases show a significant decrease in the Stage D cases. The proportion of adenocarcinoma increased, but the mucinous adenocarcinoma decreased during two decades.

CONCLUSION: These findings indicate that the pattern of colorectal cancer in China has been changing. Especially, a proximal shift due to the increasing proportion of ascending and transverse colon cancer has occurred in China.

Colonoscopic screening of average-risk women for colorectal neoplasia

BACKGROUND

Veterans Affairs (VA) Cooperative Study 380 showed that some advanced colorectal neoplasias (i.e., adenomas at least 1 cm in diameter, villous adenomas, adenomas with high-grade dysplasia, or cancer) in men would be missed with the use of flexible sigmoidoscopy but detected by colonoscopy. In a tandem study, we examined the yield of screening colonoscopy in women.

METHODS

To determine the prevalence and location of advanced neoplasia, we offered colonoscopy to consecutive asymptomatic women referred for colon-cancer screening. The diagnostic yield of flexible sigmoidoscopy was calculated by estimating the proportion of patients with advanced neoplasia whose lesions would have been identified if they had undergone flexible sigmoidoscopy alone. Lesions were considered detectable by flexible sigmoidoscopy if they were in the distal colon or if they were in the proximal colon in patients who had concurrent small adenomas in the distal colon, a finding that would have led to colonoscopy. The results were compared with the results from VA Cooperative Study 380 for age-matched men and women with negative fecal occult-blood tests and no family history of colon cancer.

RESULTS

Colonoscopy was complete in 1463 women, 230 of whom (15.7 percent) had a family history of colon cancer. Colonoscopy revealed advanced neoplasia in 72 women (4.9 percent). If flexible sigmoidoscopy alone had been performed, advanced neoplasia would have been detected in 1.7 percent of these women (25 of 1463) and missed in 3.2 percent (47 of 1463). Only 35.2 percent of women with advanced neoplasia would have had their lesions identified if they had undergone flexible sigmoidoscopy alone, as compared with 66.3 percent of matched men from VA Cooperative Study 380 (P<0.001).

CONCLUSIONS

Colonoscopy may be the preferred method of screening for colorectal cancer in women.

Determination of large bowel length and loop complexity in patients with acromegaly undergoing screening colonoscopy

BACKGROUND

Patients with acromegaly are at moderately increased risk of developing colorectal cancer and may be considered for screening colonoscopy. In turn, large bowel dimensions may be increased in these patients, factors that predict for increased risk of serious complications such as perforation.

OBJECTIVE

To evaluate this risk potential, we measured large bowel length and loop complexity using magnetic endoscopic imaging (MEI).

DESIGN

Case-control study in 25 unselected patients with acromegaly (mean age 56 years) vs. 41 nonacromegalic controls (mean age 60 years) undergoing screening colonoscopy.

MEASUREMENTS

MEI parameters were determined and age- and sex-adjusted mean differences calculated. The dependency of total large bowel length on various demographic and disease-related factors (e.g. GH exposure, IGF-I and IGFBP-3 concentrations) was assessed using regression techniques.

RESULTS

Total large bowel length was increased by 20%[95% confidence interval (CI) 9-31%] in patients with acromegaly compared with controls (unadjusted and adjusted; P-values < 0.001). Acromegaly was also associated with increased time taken to reach the caecum (P = 0.01) and increased pelvic loop complexities (5/25 vs. 1/41, Fisher's exact test: P = 0.03). Total large bowel length was predicted by age at colonoscopy (P = 0.003) and patient height (P = 0.03), but not by surrogate biochemical markers of disease activity.

CONCLUSIONS

Acromegaly is associated with increased large bowel length and loop complexity making colonoscopy technically challenging, and theoretically increasing the risk of serious complications. Patients need to be counselled accordingly, and appropriate resources with experienced staff allocated.

The incidence of colorectal cancer following a negative screening sigmoidoscopy: implications for screening interval

BACKGROUND & AIMS

Current guidelines recommend a 5-year interval for colorectal cancer (CRC) screening by sigmoidoscopy. However, the optimal screening interval is uncertain. We estimated the annual incidence of distal and proximal CRC in the first 5 years following a negative sigmoidoscopy examination to gauge the potential benefit of rescreening in <5 years.

METHODS

A cohort of 72,483 participants in the Colon Cancer Prevention program of Kaiser Permanente of Northern California (KP) was defined using computerized databases. Men and women aged 50 years and older who had a negative screening flexible sigmoidoscopy examination between 1994 and 1996 and were considered not to be at high risk for developing CRC were included. Subjects were censored at the time of diagnosis (for cases), death, termination of KP membership, or subsequent colon examination.

RESULTS

Thirty cases of distal and 80 cases of proximal CRC occurred. Age-adjusted incidence rates of distal CRC ranged from a low of 2.8 per 100,000 person-years in the first year of follow-up to a high of 13.0 per 100,000 in the fourth year (rate difference, 10.2; 95% confidence interval, 1.1-19.3). However, for the entire follow-up period, incidence of distal CRC remained much lower than age-adjusted rates of 70.6 in the general population (Surveillance, Epidemiology, and End Results registry). The incidence of proximal CRC was also decreased modestly over population rates of disease.

CONCLUSIONS

Screening by sigmoidoscopy more frequently than every 5 years would likely lead, at best, to only modest improvements as compared with a 5-year screening interval.

Screening flexible sigmoidoscopy using an upper endoscope is better tolerated by women

BACKGROUND

Flexible sigmoidoscopy (FS) is a commonly used method for colorectal cancer screening. Women are more likely than men to have a FS with a limited depth of insertion, in part due to differences of anatomy and perception of pain.

AIM

The objective of this prospective single-blinded randomized clinical study is to assess satisfaction in women undergoing screening FS using an upper endoscope (E, diameter 9.8 mm) versus a standard sigmoidoscope (S, diameter 13.3 mm) as measured by pain and discomfort and overall satisfaction using a validated survey instrument. Secondary endpoints of FS efficacy included the depth of insertion of the instrument, frequency of polyp detection, and complication rate.

RESULTS

A total of 160 asymptomatic women undergoing screening FS were entered over a 4-month period (July through November 2002). All procedures were performed by two experienced physician assistants. The two groups were of similar age (E = 57.5, S = 58.2, p= 0.579) and had a similar rate of previous abdominal surgery (E = 51.2%, S = 45.0%, p= 0.428) or hysterectomy (E = 34.2%, S = 26.3%, p= 0.274). Depth of insertion of the scope was 54.5 cm (+/-9.2 cm) with the E and 51.6 cm (+/- 10.3 cm) with the S (p= 0.058). Polyps were found more frequently in the study group (18.3%) compared with the control group (p= 10.2%) though this did not reach statistical significance (p= 0.131). Overall satisfaction with FS was similar in both groups (p= 0.694) but pain and discomfort were less in the patients undergoing FS using the E (p= 0.006). Controlling for age and previous surgery the differences in pain scores remained significant (p= 0.035). Endoscopist assessment of procedure difficulty (p= 0.726) and complication rates (p= 0.614) was equivalent. Controlling for the presence of polyps, the total duration for the procedure was 7.2 min in the E group and 5.7 min in the S group (p= 0.008). There were no significant differences between women with and without hysterectomy on either overall satisfaction or pain and discomfort.

CONCLUSION

Screening FS in women using an upper endoscope is a feasible approach to colorectal cancer screening. Patients screened with an upper endoscope reported less pain and discomfort compared to standard sigmoidoscope while overall satisfaction did not differ. The trend toward increased polyp detection in patients undergoing FS with an upper endoscope may be related to a more thorough examination due to less patient discomfort and/or an increased depth of insertion of the upper endoscope. Thinner, more flexible endoscopes should be considered when performing screening FS in women.

Evaluation of flexible sigmoidoscopy as an investigation for "left sided" colorectal symptoms

BACKGROUND

Colonoscopy is the best way of imaging the colon with concurrent biopsy and treatment. However it is expensive, requires full bowel preparation, and carries a risk of complications. Flexible sigmoidoscopy is an alternative way to investigate symptoms that raise the suspicion of a lesion of the rectum or left colon.

AIM OF THE STUDY

To evaluate flexible sigmoidoscopy as the main investigation for "left sided" colorectal symptoms.

METHODS

The clinical records of 317 patients who were assessed at a colorectal specialist clinic and were thought to have a suspicion of a lesion of the rectum or left colon were retrospectively reviewed. All patients had flexible sigmoidoscopy as the primary investigation. Primary outcome was the diagnostic yield of flexible sigmoidoscopy and secondary outcomes were any additional colonic investigations required, failure rates, and complication rates.

RESULTS

Three hundred and sixteen patients who had flexible sigmoidoscopy with the above criteria were retrospectively analysed. Twenty four procedures (7.6%) had to be abandoned because of poor bowel preparation. The examination was considered complete when it reached the splenic flexure, which was the case in 205 cases (65%). In 137 flexible sigmoidoscopies (43.3%) there were no abnormal findings. Of the remaining 179 a carcinoma of the rectum or colon was found in 28 cases (8.8%) and one or more polyps was found in 57 (18%) cases. On the basis of the findings it was calculated that 31% of the patients would require an additional investigation for further imaging of the right colon.

DISCUSSION

Although flexible sigmoidoscopy has a high yield of pathologies when carried out by a specialist colorectal clinic, the presence of those pathologies makes the full imaging of the whole colon with an additional investigation necessary. Therefore the cost efficiency of flexible sigmoidoscopy is questionable. Although flexible sigmoidoscopy is indicated for certain patients, it cannot replace colonoscopy as the main investigation used by a specialist colorectal clinic.

Colorectal cancer screening with flexible sigmoidoscopy—participants' experiences and technical feasibility

AIM

To evaluate tolerability and technical feasibility of colorectal cancer screening with flexible sigmoidoscopy.

METHODS

One thousand men and women aged 59-61 years, randomly selected from the population register of Uppsala, Sweden, were invited by mail. After random allocation, half of them were called up by a nurse (group 1), while the other half were asked to call themselves (group 2) to book a sigmoidoscopy. After the examination, the participants anonymously answered a questionnaire about their subjective experiences. Endoscopists and their assisting nurse filled out structured forms documenting various technical aspects including an estimation of the subjects' discomfort.

RESULTS

Four hundred and sixty-nine subjects participated. Mean intubation depth was 59 cm (range 28-60) and mean duration 5.8 min (range 2-23). On average, participants reported low degrees of discomfort and feeling of exposure, but 19 and 27% rated pain and distension, respectively, on the upper half of a visual analogue scale (VAS). Most subjects found the duration acceptable. Patient discomfort, as appraised by the endoscopists, was lower in men than in women, positively linked to duration of the procedure, but inversely associated with intubation distance. However, the overall differences between strata of participants were small. Among self-reported variables, group 1 and 2 differed significantly only with regard to 'other discomfort'. All but six subjects would accept a repeat examination. Failures, resulting in incomplete examinations, occurred in 14 subjects.

CONCLUSIONS

Flexible sigmoidoscopy is generally well tolerated and technically feasible in screening for colorectal cancer. A more personalised invitation did not have any important effects on the subjective experience.

Association of older age and female sex with inadequate reach of screening flexible sigmoidoscopy

PURPOSE

Estimates of the sensitivity of screening sigmoidoscopy assume an adequate depth of insertion is reached. However, in clinical practice, the frequency that sigmoidoscopy reaches various lengths of the colon is not known. We assessed the frequency of inadequate reach (depth of <50 cm of the colon) in a large U.S. cohort, according to age and sex.

METHODS

We performed a cross-sectional study of 15,406 asymptomatic persons aged 50 years or older who underwent screening flexible sigmoidoscopy between April 1997 and October 2001 at sites participating in the Clinical Outcomes Research Initiative, which examines outcomes of endoscopy in "real life" settings. The maximum depth of insertion of the sigmoidoscope was measured in centimeters from the anus and classified as adequate (> or =50 cm) or inadequate (< 50 cm). Patient characteristics as well as procedure-related variables were also recorded.

RESULTS

Eighteen percent (n = 2801) of subjects had an inadequate examination. In men, the percentage of inadequate examinations increased progressively with age, from 10% (343/3338) in those aged 50 to 59 years to 22% (53/248) in those aged 80 years or older (P <0.001). Inadequate examinations were more common in women at all ages, ranging from 19% (733/3798) in those aged 50 to 59 years to 32% (86/267) in those aged 80 years or older (P <0.001). These associations were confirmed in a multivariable analysis.

CONCLUSION

Our finding that advancing age and female sex were independently associated with the risk of inadequate reach of screening sigmoidoscopy suggests that the sensitivity of sigmoidoscopy may be lower in these populations. Estimates of the benefits of sigmoidoscopy may need to be tailored to the age and sex of the patient.

Appropriateness of diagnostic digestive endoscopy

The indications of diagnostic endoscopy--upper gastrointestinal endoscopy or colonoscopy--in the exploration of the digestive tract are classified as appropriate or inappropriate with regard to criteria established in guidelines supported by national scientific societies and by insurance companies. This applies to the exploration of symptomatic patients and to screening protocols for malignant lesions. Functional or nonstructural diseases being more frequent than structural diseases, negative findings in endoscopy are common. However this reassures the patient and should not be considered as overuse. On the other hand excess in the repetition of negative endoscopic procedures during surveillance raises ethical problems, increased costs, and may be considered as unethical.

Change in anatomic distribution and incidence of colorectal carcinoma over a period of 15 years: clinical considerations

PURPOSE

Colorectal cancer is the second most common cancer in the Netherlands. Its incidence rates are among the highest in Europe. In the past decades, a right-sided shift of the subsite location of colorectal cancer has been reported. These changes in anatomic distribution might have clinical implications for the use of diagnostic or screening tools for colorectal cancer. This study was designed to investigate the change in incidence and anatomic distribution of colorectal cancer in a population over a period of 15 years.

METHODS

The incidence of colorectal cancer in an eastern part of the Netherlands (700,000 inhabitants) was determined for two years, 1981 and 1996. From the regional laboratory of pathology, data including age, gender, subsite location, and Dukes classification were collected. The subsite location of colorectal cancer was divided into two groups: proximal and distal (the latter being within sigmoidoscopy reach).

RESULTS

No differences in age and gender distribution were found. In 1981, the diagnosis of colorectal cancer was made in 232 patients in this region, and in 1996, it was made in 410 patients. The population remained almost stable during this time. Therefore, the incidence rose from 33 to 55 per 100,000 inhabitants from 1981 to 1996, respectively. In 1981, 25 percent of the carcinomas were proximal (to the sigmoid colon); this increased to 37 percent in 1996 ( P< 0.05).

CONCLUSIONS

The incidence of colorectal cancer has almost doubled from 1981 to 1996 in this Dutch region. The proportion of proximal colorectal cancer has increased from 25 to 37 percent. These findings add to the notion that sigmoidoscopy is not the optimal diagnostic or screening tool for colorectal cancer.

Rationale for colonoscopy screening and estimated effectiveness in clinical practice

Colonoscopy screening has the highest anticipated level of effectiveness of the available colorectal cancer screening techniques. Its long-term cost-effectiveness is also comparable with or superior to other modalities. Evidence for the expected reduction in colorectal cancer incidence and mortality varies with colonoscopy screening from 50% to 90%, for reasons that are not fully understood. Maintaining a high standard of performance is critical with regard to achieving the highest level of effectiveness possible.

Flexible sigmoidoscopy: an important screening option for average-risk individuals

Colorectal cancer screening techniques should be effective, acceptable to patients, affordable, widely available, and safe. For average-risk adults aged more than 50 years who do not have significant colorectal symptoms, significant family history, or significant predisposing conditions, flexible sigmoidoscopy is an important option for reducing the risk for colorectal cancer, meeting all criteria for an effective and feasible screening modality. This article discusses evidence supporting flexible sigmoidoscopy, practical issues in implementation, and current controversies.

Achieving quality in flexible sigmoidoscopy screening for colorectal cancer

BACKGROUND

Sigmoidoscopy screening, which can dramatically reduce colorectal cancer mortality, is supported increasingly by physicians and payers, and is likely to be performed more frequently in the future. As more physicians and nonphysician medical personnel learn how to perform this procedure, and with attention to quality standards, the overall impact of sigmoidoscopy screening may improve. This review describes elements that characterize high-quality examinations and identifies resources for in-depth information on performing flexible sigmoidoscopy.

METHODS

The domains of quality were identified from textbooks, articles, and the professional opinions of gastroenterologists and primary care physicians. Information was obtained from MEDLINE, bibliographies in recent articles, medical professional organizations, equipment manufacturers' representatives, and focus groups of primary care physicians.

RESULTS

Nine domains of quality are identified and discussed: training, logistical start-up, patient interaction, bowel preparation, examination technique, lesion recognition, complications, reporting, and processing (equipment cleaning and disinfection).

CONCLUSIONS

Persons learning how to perform and to implement flexible sigmoidoscopy may use this information to help ensure the quality of screening examinations.

Effect of magnetic endoscope imaging on colonoscopy performance: a randomised controlled trial

BACKGROUND

Colonoscopy can be technically challenging because of unpredictable colonoscope looping. Without imaging, straightening the colonoscope is sometimes difficult since the endoscopist has to guess where the tip is. Magnetic endoscope imaging (MEI), a new non-radiographical technique for picturing the colonoscope shaft in real time, could facilitate loop straightening and thus improve performance.

METHODS

We assessed trainees and endoscopists with much experience of routine outpatient colonoscopy. In group 1, trainees examined 113 consecutive patients. MEI views were recorded in all examinations, but procedures were randomised to be done by two trainees, either with the endoscopist and endoscopy assistants viewing the imager display (n=58), or without the imager view (n=55). In group 2, two skilled endoscopists were randomised (as with group 1) to undertake consecutive examinations (n=183) either with (n=92) or without (n=91) the MEI view. MEI views of all procedures were analysed retrospectively.

FINDINGS

In both groups, intubation times were shorter (median 11.8 min [4.3-31.5] vs 15.3 min [4-67] [group 1]; 8.0 min [2.6-40.8] vs 9.3 min [2.5-52.6] [group 2]) and number of attempts at straightening the colonoscope fewer (median 5 [0-20] vs 12 [0-57] [group 1]; 7 [0-55] vs 10 [0-80] [group 2]), when the endoscopist was able to see the imager view. In group 1, colonoscopy completion rates were also higher (100% [58] vs 89% [49]) and duration of looping was reduced (median 3 min [0-18.8] vs 5.4 min [0-44.5]) when the imager could be seen. Abdominal hand pressure was more effective when the endoscopist and endoscopy assistant could see the imager view.

INTERPRETATION

MEI significantly improves performance of colonoscopy, particularly when used by trainees, or by experts in technically difficult cases; loops were straightened or controlled effectively, resulting in quick intubation times and high completion rates.

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.

Colonoscopy aided by magnetic 3D imaging: is the technique sufficiently sensitive to detect differences between men and women?

Colonoscopy tends to be more difficult to perform in women. Women also experience more pain during flexible sigmoidoscopy, and the mean insertion distance of the instrument is less than in men. The 'Bladen system', first described in 1993, is a non-radiological method of continuously visualising the path of the endoscope using magnetic drive coils under the patient and a chain of sensors up the biopsy channel of the instrument. In 1998, results were published that used a novel computer graphics system (the 'RMR system'), in which a much more realistic endoscope could be produced using the stored positional data from the Bladen system. The RMR computer graphics system has been further refined to enable measurement of the anatomical lengths of different parts of the large intestine to an accuracy of greater than 5 mm. The system is used to analyse the results obtained in 232 patients undergoing a total colonoscopy. In women, the colonoscope tends to form loops in the sigmoid colon more readily than in men (p < 0.05). When the first 50 cm of the endoscope are inserted for the first time, the tip passes either up to or beyond the splenic flexure in 40/116, or 34.5%, of males, compared with 24/117, or 20.5%, of females (p = 0.0137). It is demonstrated that women have longer transverse colons than men, and the differences are especially apparent when a stiffening tube is used to splint the left side of the colon (p < 0.0001). The possible relevance of these observations to biomedical engineers and those manufacturing and assessing prototype endoscopes is discussed.