Double contrast enema and colonoscopy in polyp detection

The Double Contrast Barium Enema in the Identification of Proximal Colonic Adenomas and Carcinomas beyond the Limits of Fiberoptic Sigmoidoscopy

Eight hundred and twenty patients were examined by fiberoptic sigmoidoscopy (SIG) and double contrast barium enema (DCBE) to detect colonic cancers or adenomas. Cancer or adenoma in the bowel tract proximal to the upper limit of SIG insertion was detected in 4-patients and in 12 on DCBE. The DCBE detection rate of proximal colonic lesions varied according to the hemoccult (HO) outcome. This was 1.16 % for cancer and 2.03 % for adenoma in HO+ patients and null for cancer and 1.23 % for adenoma in HO–- patients. The detection rate of proximal adenomas was higher in patients who presented adenomas on endoscopy in the distal bowel (SIG+), 2.46 % as compared to 0.48 % in SIG- patients,. independent of the HO reports. Routine DCBE is practically useless in HO-SIG- patients and questionable in HO-SIG+ patients since improvement of the detection rate is null for cancer and moderate for adenoma. It is recommended for HO+ patients because it increases the colonic cancer detection rate (10.5 % in this study).

Accuracy of Double Contrast Barium Enema and Sigmoideoscopy in the Detection of Polyps in Patients with Diverticulosis

The sensitivity between double contrast barium enema (DCBE) and sigmoideoscopy in diagnosing neoplastic lesions in the sigmoid colon was compared in patients with diverticulosis. In 52 patients with severe diverticulosis (≥15 diverticulas) the DCBE detected one out of 4 polyps found by sigmoideoscopy. In the remaining 54 patients with mild diverticulosis (<15 diverticulas) DCBE detected 7 out of 10 polyps found by sigmoideoscopy. Successful bowel preparation did not influence the outcome of the DCBE. Sigmoideoscopy was incomplete in 17 (16%) of the patients; females were more difficult to examine than males (p= 0.012), as were those with a previous pelvic operation (p= 0.032). We conclude that neither DCBE nor sigmoideoscopy alone is sufficient to detect all neoplastic lesions in the sigmoid colon in patients with sigmoid diverticulosis of the colon.

Radiographic Findings in Overlooked Colon Carcinomas

Double contrast barium enemas in 21 patients with primarily overlooked colon carcinomas were reviewed. The carcinomas were flat and measured less than 30 mm in 18 cases. These tumours constitute almost 1.4 per cent of the carcinomas diagnosed during a 12-year period. The retrospective analysis revealed the following signs of carcinoma: missing haustral folds, disharmony of interhaustral fold patterns; radiolucent filling defects; local contractions; residue-like masses and decrease of volume. In all cases, at least two secondary signs of carcinoma, range 1.7 to 3, were seen.

The Diagnostic and Prognostic Role of microRNA in Colorectal Cancer - a Comprehensive review

The discovery of microRNA, a group of regulatory short RNA fragments, has added a new dimension to the diagnosis and management of neoplastic diseases. Differential expression of microRNA in a unique pattern in a wide range of tumor types enables researches to develop a microRNA-based assay for source identification of metastatic disease of unknown origin. This is just one example of many microRNA-based cancer diagnostic and prognostic assays in various phases of clinical research.

Since colorectal cancer (CRC) is a phenotypic expression of multiple molecular pathways including chromosomal instability (CIN), micro-satellite instability (MIS) and CpG islands promoter hypermethylation (CIMP), there is no one-unique pattern of microRNA expression expected in this disease and indeed, there are multiple reports published, describing different patterns of microRNA expression in CRC.

The scope of this manuscript is to provide a comprehensive review of the scientific literature describing the dysregulation of and the potential role for microRNA in the management of CRC. A Pubmed search was conducted using the following MeSH terms, "microRNA" and "colorectal cancer". Of the 493 publications screened, there were 57 papers describing dysregulation of microRNA in CRC.

Colon cancer screening update and management of the malignant polyp

Colorectal carcinoma is common, but screening for this cancer has found less acceptance with the public than screening for breast, prostate, and cervical cancer. Available methods include fecal occult blood tests (FOBTs), flexible sigmoidoscopy (FOS), double-contrast barium enema, colonoscopy, computed tomographic colography, and fecal DNA. Evaluation of these options demonstrates that colonoscopy at ages 55 and 65 offers the best combination of reduction in colorectal cancer at the lowest cost. However, when compliance with screening recommendations is very high, costs are high, and the proportion of cancers arising from adenomas is low, the combination of FOS and FOBT is most cost effective. Malignant polyps look friable and irregular and feel hard. Sessile malignant polyps need to be treated by formal resection. Patients with pedunculated polyps with favorable histology (clear margin, well or moderately differentiated, no lymphovascular invasion) can be observed, and those whose polyps show unfavorable histology should have the polyp-bearing segment of colon resected along with its draining lymph nodes.

Virtual colonoscopy vs optical colonoscopy

IMPORTANCE OF THE FIELD: The high prevalence of colon carcinoma combined with the low compliance of currently recommended screening guidelines explains the continued high mortality rate of colon cancer. Utilizing a strategy of virtual colonoscopy (VC) in asymptomatic patients over 50, with optical colonoscopy (OC) follow-up for removal of detected adenomatous polyps may result in lowering the colon cancer death rate. However, the screening potential of VC has not yet been widely recognized. Debates and doubts of its potential benefits have been frequently seen in the literature since VC was first reported in 1994. AREAS COVERED IN THIS REVIEW: This article reviews the currently available screening options and discuss their advantages and drawbacks. TAKE HOME MESSAGE: VC has many advantages over the existing screening options and its several drawbacks can be mitigated so that it would become a valuable screening modality. A strategy that utilizes VC for population-based screening over the age of 50 and OC for screening high-risk individuals and those with positive VC findings would result in a significantly reduced rate of colon cancer deaths.

An update on imaging of colorectal cancer

Screening of asymptomatic average-risk patients for presence of colon cancer and early detection in precursor stages is of great interest to general population. Comprehensive evaluation of symptomatic or high-risk patients represents another important clinical focus. Available techniques for total colon imaging, rectal cancer staging and the role of positron emission tomography are discussed.

Colorectal cancer screening and surveillance: current standards and future trends

Its prevalence, long premalignant course, and favorable response to early intervention make colorectal cancer an ideal target for screening regimens. The success of these regimens depends on accurate assessment of risk factors, patient compliance with scheduled visits and tests, and physician knowledge of screening strategies. We review the current recommendations for colorectal cancer screening in general and at-risk populations, comment on surveillance methods in high-risk patients, and examine current trends that will likely influence screening regimens in the future.

Quality control issues in the management of colon cancer patients

Quality assurance in colon cancer demands a multidisciplinary effort involving general practitioners, surgeons, radiologists, gastroenterologists, medical oncologists, and pathologists, among others. Maximal improvements in survival will result when colon cancer screening, diagnosis, staging, treatment and surveillance are optimized. We seek to identify those issues most relevant to the quality of care we provide our colon cancer patients.

The evaluation of rectal bleeding in adults. A cost-effectiveness analysis comparing four diagnostic strategies

BACKGROUND

Though primary care patients commonly present with rectal bleeding, the optimal evaluation strategy remains unknown.

OBJECTIVE

To compare the cost-effectiveness of four diagnostic strategies in the evaluation of rectal bleeding.

DESIGN

Cost-effectiveness analysis using a Markov decision model.

DATA SOURCES

Systematic review of the literature, Medicare reimbursement data, Surveillance, Epidemiology, and End Results (SEER) Cancer Registry.

TARGET POPULATION

Patients over age 40 with otherwise asymptomatic rectal bleeding.

TIME HORIZON

The patient's lifetime.

PERSPECTIVE

Modified societal perspective.

INTERVENTIONS

Watchful waiting, flexible sigmoidoscopy, flexible sigmoidoscopy followed by air contrast barium enema (FS+ACBE), and colonoscopy.

OUTCOME MEASURES

Incremental cost-effectiveness ratio.

RESULTS OF BASE-CASE ANALYSIS

The incremental cost-effectiveness ratio for colonoscopy compared with flexible sigmoidoscopy was 5,480 dollars per quality-adjusted year of life saved (QALY). Watchful waiting and FS+ACBE were more expensive and less effective than colonoscopy.

RESULTS OF SENSITIVITY ANALYSES

The cost of colonoscopy was reduced to 1,686 dollars per QALY when age at entry was changed to 45. Watchful waiting became the least expensive strategy when community procedure charges replaced Medicare costs, when age at entry was maximized to 80, or when the prevalence of polyps was lowered to 7%, but the remaining strategies provided greater life expectancy at relatively low cost. The strategy of FS+ACBE remained more expensive and less effective in all analyses. In the remaining sensitivity analyses, the incremental cost-effectiveness of colonoscopy compared with flexible sigmoidoscopy never rose above 34,000 dollars.

CONCLUSIONS

Colonoscopy is a cost-effective method to evaluate otherwise asymptomatic rectal bleeding, with a low cost per QALY compared to other strategies.

Prospective comparison of air-contrast barium enema and colonoscopy in patients with fecal occult blood: a pilot study

BACKGROUND

The utility of air-contrast barium enema and colonoscopy for evaluation of the colon has been debated. Air-contrast barium enema is less expensive and invasive than colonoscopy, but it also is less sensitive and specific. Further, although air-contrast barium enema may be less painful than colonoscopy, it often is poorly tolerated by patients. Thus, this study compared the sensitivity and the specificity of air-contrast barium enema and colonoscopy for detection of colonic lesions in patients with fecal occult blood.

METHODS

Over a 30-month period, patients with fecal occult blood were recruited. Patients underwent standard air-contrast barium enema, followed by colonoscopy 7 to 14 days later. Colonoscopists were blinded to the results of air-contrast barium enema until the colonoscopy was completed, after which the results were disclosed. If the findings were discrepant, colonoscopy was repeated.

RESULTS

A total of 100 patients were evaluated. Nine air-contrast barium enemas were reported to be inadequate, and the cecum was not intubated at colonoscopy in two patients. In the remaining patients, 5 cancers were identified (1 each cecum, transverse colon, descending colon, sigmoid colon, and rectum) by both studies. Sixty-six polypoid lesions were identified in 30 patients. Diverticula were identified in 42 patients by air-contrast barium enema and in 18 patients by colonoscopy. Air-contrast barium enema detected 3 of 36 polypoid lesions 5 mm or less in diameter, 5 of 15 adenomas 6 to 9 mm in size, and 4 of 15 adenomas 10 mm or greater in diameter (sensitivity 8%, 33%, and 27%, respectively). After excluding patients with diverticula, air-contrast barium enema detected 3 of 7 adenomas 10 mm or greater in size. Overall, 12 polypoid lesions or filling defects were identified by air-contrast barium enema that could not be verified by colonoscopy. The specificity of air-contrast barium enema for lesions 1.0 cm or greater in size was 100%; for those 6 mm or greater, it was 97%.

CONCLUSIONS

Air-contrast barium enema accurately detects colon cancer and diverticula. Its sensitivity for detection of polypoid lesions or adenomas is poor and was confounded by the presence of diverticula.

Adherence to colorectal cancer screening in mammography-adherent older women

Colorectal cancer (CRC) is the third leading cause of cancer mortality among women. Screening can prevent the development of CRC or diagnose early disease when it can effectively be cured, however existing screening methods are underutilized. In this study, we examined the utility of an updated Health Belief Model to explain CRC screening adherence. The present study included 280 older women seeking routine mammography at a large, urban breast diagnostic facility. Overall, 50% of women were adherent to CRC screening guidelines. Multiple regression indicated that self-efficacy, physician recommendation, perceived benefits of and perceived barriers to screening accounted for 40% of variance in CRC screening adherence. However, there was no evidence for two mediational models with perceived benefits and perceived barriers as the primary mechanisms driving adherence to CRC screening. These findings may inform both future theoretical investigations as well as clinical interventions designed to increase CRC screening behavior.

Colonoscopy in asymptomatic individuals with a family history of colorectal cancer

BACKGROUND

This study was performed to evaluate the use of total colonoscopy as the optimal screening test in asymptomatic individuals with a family history of colorectal cancer (CRC).

METHODS

Colonoscopy was performed in 249 asymptomatic individuals who had one or two first-degree relatives (FDRs) with CRC; individuals with three or more FDRs with CRC were excluded.

RESULTS

Eighty-six colonic lesions were found in 51 individuals (51 of 249; 20.5%). Among these 51 subjects, 27 had neoplastic polyps (n = 38) and 29 had metaplastic polyps (n = 44). Although no invasive cancer was detected, in 14 individuals the lesions had a high malignancy potential because of their size and histopathology. We did not confirm a statistically significant difference in the incidence of neoplastic polyps according to the number of affected FDRs. Finally, the presence of metaplastic polyps was a very strong indication for the concomitant presence of metaplastic polyps (P <.0001).

CONCLUSIONS

Total colonoscopy is the optimal screening procedure for the examination of asymptomatic individuals with a family history of CRC.

Caecal carcinomas in the elderly: useful signs in minimal preparation CT

OBJECTIVE

Frail, elderly and immobile patients frequently have difficulty in tolerating formal colonic investigations. Caecal tumours may account for up to 35% of colonic tumours. Barium enema and colonoscopy have limitations in assessing this region. The aims of this study were to evaluate the accuracy of a minimal preparation CT technique (merely with prolonged oral contrast medium) in identifying caecal carcinomas and to determine helpful radiological signs.

MATERIALS AND METHODS

The CT technique involved helical acquisition following 2 days of preparation with oral contrast medium. The outcome of 4 years' experience (1995-1998) was reviewed. The gold-standards were pathological and cancer registration records, together with colonoscopy and barium enema where available, with a minimum of 15 months' follow-up.

RESULTS

CT correctly identified 27 of 30 caecal carcinomas, and missed three, in a total of 1077 CT studies in 1031 patients (median age 80 years). There were also 21 false-positive cases in which CT incorrectly raised the possibility of a caecal tumour. The sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were 90%, 98%, 99% and 56%, respectively. Serosal margin blurring, tumour length, presence of abnormal peri-colic fat and terminal ileal wall thickening were identified as useful radiological signs.

CONCLUSIONS

Minimal preparation CT is able to identify caecal carcinomas with fair accuracy. Such evaluation may become important given the increasing population age and evidence of a 'proximal shift' in the site of colonic tumours in the elderly.

Colorectal cancer screening participation: comparisons with mammography and prostate-specific antigen screening

OBJECTIVES

The relation of personal characteristics, health and lifestyle behaviors, and cancer screening practices to current colorectal cancer (CRC) screening was assessed and compared with those factors' relation to current mammography screening in women and prostate-specific antigen (PSA) screening in men.

METHODS

A cross-sectional random-digit-dialed telephone survey of 954 Massachusetts residents aged 50 and older was conducted.

RESULTS

The overall prevalence of current CRC screening was 55.3%. Logistic regression results indicated that family history of CRC (odds ratio [OR] = 1.98; 95% confidence interval [CI] = 1.02, 3.86), receiving a regular medical checkup (OR = 3.07; 95% CI = 2.00, 4.71), current screening by mammography in women and PSA in men (OR = 4.40; 95% CI = 2.94, 6.58), and vitamin supplement use (OR = 1.87; 95% CI = 1.27, 2.77) were significant predictors of CRC screening.

CONCLUSIONS

Health and lifestyle behaviors were related to increased current CRC, mammography, and PSA screening. Personal factors independently related to CRC screening were not consistent with those related to mammography and PSA screening. This lack of consistency may reflect different stages of adoption of each type of screening by clinicians and the public.

Barium enema and endoscopy for the detection of colorectal neoplasia: sensitivity, specificity, complications and its determinants

AIM

To analyse sensitivity, specificity and complication rate of endoscopy, and barium enema for the detection of colorectal neoplasia.

MATERIALS AND METHODS

A MEDLINE search was performed (1980-2000) directed at the endoscopic and radiologic literature on barium enema. Articles were selected based on the type of study, availability of sensitivity and specificity values in sizeable patient groups, and reports on complications. Sixty articles were included in the analysis.

RESULTS

Endoscopy proved to have superior sensitivity for polyps in patients at high-risk for colorectal neoplasia. The role of endoscopy and radiology in average-risk screening populations is not known. Sensitivity and specificity rates ranged widely, probably due to bias. For the detection of small polyps endoscopy has superior performance, whereas sensitivity is similar for endoscopy and barium enema for the detection of larger (>1 cm) polyps and tumours. Overall, endoscopy is associated with a higher complication rate.

CONCLUSION

Endoscopy is the preferred detection method in high-risk patients. The role of endoscopy and radiology in a screening setting requires evaluation. This review provides the test characteristics of endoscopy and radiology which are relevant for a cost-effectiveness analysis. Double-contrast barium enema may play an important role for screening purposes, owing to its good sensitivity for detecting larger (>1 cm) polyps and its lack of major complications. de Zwart, I. M.et al. (2001). Clinical Radiology56, 401-409.

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

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Screening for colorectal cancer

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

AGA technical review on the evaluation and management of occult and obscure gastrointestinal bleeding

This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics committee. The paper was approved by the committee on May 16, 1999, and by the AGA governing board on July 18, 1999.

Screening for colorectal cancer: present, past and future

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

Screening and surveillance for colorectal carcinoma

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

Hydrosonography in the evaluation of colorectal polyps

Prewarmed saline enemas and transabdominal ultrasound (hydrosonography) were used to evaluate 17 consecutive children with rectal bleeding before colonoscopy. Twelve patients with polyps were identified (10 by ultrasound, 10 by endoscopy): these included multiple hyperplastic polyps (1), multiple polyps (1), solitary polyps (9), and pseudopolyps (1). Ultrasound identified 11 polyps in 10 patients, missing two patients with small polyps less than 0.5 cm in diameter. The polyps were hyperechoic ovoid masses fixed to the colonic wall, with a stalk (7), submucosal infolding (5), and intraluminal floating (5). There was one false positive. Colonoscopy was refused by one patient and failed to reach beyond the distal sigmoid in another following previous surgery for malrotation. Colonoscopy was superior in identifying finer mucosal detail (colitis, ulcers, proctitis, anal fissure) and in detecting smaller polyps (sessile polyps, hyperplastic polyps). Hydrosonography of the colon is a simple, relatively non-invasive procedure that provides an alternative, radiation-free examination of the whole colon before colonoscopy. It is complementary to colonoscopy in the management of rectal bleeding in children.

Double-contrast barium enema study with computed radiography: assessment in detection of colorectal polyps

Feasibility and diagnostic performance of digital radiography in gastrointestinal imaging have not been fully investigated. We performed double-contrast barium enema study with computed radiography (CR-DCBE) on a routine basis, and the efficacy of this system for detection of colorectal polyps was investigated. The files of 76 patients, who had undergone both CR-DCBE and colonoscopy, were reviewed by two observers who were blinded to the colonoscopic findings. The radiation dose of CR-DCBE was reduced to 50% of conventional film-screen system. By using colonoscopic findings as a reference, the sensitivity and positive predictive value for colorectal polyps were 66% to 71% and 32% to 41%, respectively. There was no significant interobserver difference. The use of postprocessing with gray-scale reversal and edge enhancement did not significantly improve the results. The sensitivity for polyps smaller than 1 cm was comparable with published data of conventional film-screen systems. Our preliminary results show that CR-DCBE has an acceptable sensitivity for detection of colorectal polyps. It is suggested that the use of CR is a promising approach to digital gastrointestinal radiography.

Cost-effectiveness analysis of strategies for colorectal cancer screening in Japan

To determine the cost-effectiveness of colorectal cancer screening strategies in Japan and to determine the influence of long-term compliance with screening programs on the selection of strategies, the natural history of a simulated cohort of 40-year-old Japanese of both genders was modeled with and without colorectal cancer screening until age 75 years. Survival, number of complications, and direct medical costs were compared among several combinations of screening examinations. In addition, the age of initiating screening was varied, as was the long-term compliance rate. Strategies using immunological fecal occult blood test were found to be the most cost-effective. Immunological fecal occult blood test followed by colonoscopy, if positive, would save 24.05 (5.88 discounted) days of life and cost 28,420 yen (US $210) per screened person, thus offering a cost-effectiveness ratio of 1.765 million yen (US $13,100) per year of life saved. If long-term compliance is 100%, initiating screening at age 40 years offers more years of life saved and a low incremental cost of screening. However, if more likely dropout rates are considered, initiation at age 40 years is dominated by later initiation of screening.

Benign colorectal neoplasms undetected by colonoscopy

This retrospective investigation assessed the sensitivity of colonoscopy for the detection of colonic polyps seen previously at barium enema examination. Included in the study were 77 patients with 106 polypoid lesions. Films showing lesions not subsequently seen at colonoscopy were reviewed and only those lesions with a visible point of attachment, exhibiting no movement in response to filling or change in position of the patient, and confidently diagnosed as a polyp by both reviewing radiologists were included among the 106 lesions. Sixteen lesions (15%) seen radiologically were not located colonoscopically, indicating an endoscopic sensitivity of 85%. Contrary to previous reports, most of the lesions missed endoscopically were in the left colon in regions thought to have been traversed by the instrument. The 15% false-negative rate found for colonoscopy is consistent with existing reports on colonoscopic errors and is approximately the same as the false-negative error rate for radiologic detection of colonic polyps.

Colorectal cancer: the case for barium enema

Both colonoscopy and barium enema are important techniques for examining the colon for polyps and cancer. They are approximately equally sensitive in detecting polypoid lesions of 7 to 10 mm or larger. A major limitation of colonoscopy is that the cecum cannot be visualized in 10 to 36% of cases. The comparable accuracy for detecting significant lesions, greater safety, and greater cost-effectiveness of barium enema favor its use in most patients.

Is colonoscopic screening appropriate in asymptomatic patients with family history of colon cancer?

Colonoscopy has been advocated by some investigators as the most appropriate means of screening asymptomatic patients with a positive family history of colorectal cancer. However, results of such screening have been widely disparate. The purpose of this study was to evaluate the yield of colonoscopy in a cohort of completely asymptomatic individuals with one or two first-degree relatives with a history of colorectal cancer and to compare this yield with that of colonoscopy in a group of patients with apparent anal bleeding. Patients with possible genetic disorders, such as familial polyposis, were excluded. A total of 160 asymptomatic patients and a comparison group of 137 patients with nonacute anorectal bleeding underwent colonoscopy. Colonoscopy was completed in 143 of the 160 study patients (89 percent) and in all of the comparison patients and did not result in any complications. Twenty-two adenomas were found in 17 study patients (10.6 percent); 16 of the 22 adenomas were less than 1 cm in size. In the comparison group, eight adenomas were identified (5.8 percent of patients). No cancers were identified. The difference in polyp frequency between groups was not significant. The relatively low yield of colorectal neoplasms discovered at colonoscopy in this study may in part be due to the small sample size or to the strict criteria used to define these asymptomatic patients but does not lend strong support to the notion that colonoscopy is an appropriate first step in screening the asymptomatic patient with one or two first-degree relatives with colon cancer.

Is evaluation of the right colon necessary prior to cecocystoplasty?

Use of the ileocecal bowel segment in urological surgery has become more widespread. Thorough preoperative evaluation of the bowel is seldom performed. A case is presented in which the intraoperative finding of numerous cecal polyps led to abortion of a planned cecocystoplasty. The literature on fecal occult blood testing and screening methods for colorectal neoplasia was reviewed. Patients are classified into 2 categories, average risk and high risk, according to the relative risk for colorectal neoplasia. The data suggest that the fecal occult blood test, if properly performed, is an adequate screening tool for average risk patients. However, because of the high rate of false negative results this test is inadequate for evaluation of high risk patients. It is recommended that such patients should undergo preoperative screening colonoscopy regardless of the fecal occult blood test result.

Through the colonoscope--a radiologist's view

A series of 1578 consecutive colonoscopies performed by radiologists in training is reviewed, with specific reference to patients with colorectal neoplasms. The contribution of the radiologist to the practice of colonoscopy is discussed. This input to the colonoscopy service of a hospital carries several benefits, including the following: a link is established between radiologists and gastroenterologists which improves the standard of both barium enema and colonoscopic examinations; informed discussion is made possible about the suitability of a barium enema lesion for endoscopic removal; the endoscoping radiologist acquires an impartial view of each examination and is able to choose the more appropriate investigation; direct visualisation of the colonic mucosa and its abnormalities may facilitate the interpretation of barium radiographs and enhance the quality of the radiological training that can be offered. In our experience, participation in a weekly colonoscopy session has had no adverse effect on the routine work of the radiology department.

Spatial clustering of multiple hyperplastic, adenomatous, and malignant colonic polyps in individual patients

Analysis of relative polyp locations in 426 consecutive patients with multiple colonic polyps found on colonoscopy showed novel findings. First, synchronous and metachronous neoplastic polyps showed spatial clustering in individual patients. For example, patients with their largest neoplasm in the cecum or proximal ascending colon, had 34.3 percent +/- 4.6 percent (standard error) of their other colonic neoplasms in the same location. Second, hyperplastic polyps showed spatial clustering in individuals that was statistically significantly greater than expected from the increased hyperplastic polyp concentration in the rectum and sigmoid. Third, hyperplastic polyps showed spatial clustering with neoplastic polyps; this clustering was similar in magnitude to clustering for exclusively hyperplastic or neoplastic polyps. In contrast, lipomas were not spatially clustered with hyperplastic and neoplastic polyps. The magnitude of clustering between hyperplasia and neoplasia showed a closer association between these histologic types than previously appreciated. Because of clustering, regions with prior polyps appear to merit closer surveillance. These findings suggest clinical study, using a randomized controlled clinical trial, of whether a patient who had only rectal and sigmoid adenomas on initial and follow-up colonoscopy should have surveillance with flexible sigmoidoscopy alternating annually with colonoscopy. A patient with a prior cecal adenoma should have surveillance only with a complete colonoscopy or adequate cecal views on barium enema.

Radiological evidence for the polyp/cancer sequence in the colon

Three cases of frank malignancy developing in pre-existing colonic polyps are presented. Although this sequence of events is well recognised, it is rarely demonstrated radiologically. The cases illustrate the importance of identifying and appropriately treating polypoid colonic lesions.

Colorectal polyps: a correlation of radiological and pathological findings

Ninety colorectal polyps seen on double contrast barium enema were reviewed and note was made of surface and base characteristics, size, site and the presence of associated disease. Results were then correlated with the histology. The radiological characteristics of each histological type of polyp encountered are described. Because of the variation in radiological appearance of each histological type and similarities in appearance between these types, we conclude that radiology cannot accurately predict the histology of a colorectal polyp.

Endoscopic examination of the colon in infancy and childhood

Flexible fiberoptic colonoscopy is a safe and effective diagnostic procedure in infants and children. It is a sensitive and practical procedure that has made substantial contributions to the diagnosis and treatment of colonic disorders in infants and children. With further refinements in technique, future applications of its use are likely to occur.

Colonoscopy in the diagnosis of colorectal cancer

Many studies show that colonoscopy is the most accurate method available in the diagnosis of colorectal cancer. Furthermore, in some cases it makes it possible to treat malignant polyps adequately by simple polypectomy. Endoscopic removal of adenomas plays an important role in prevention of colorectal malignancies. It has also been shown that there is a high rate of synchronous premalignant and malignant lesions.

Problems in the colonoscopic localization of tumors: continued value of the barium enema

Six patients in whom errors of diagnosis and therapy occurred because of reliance on colonoscopic tumor localization are presented. Three of the patients required a second laparotomy for surgical resection of a tumor that was missed at the first exploration. While endoscopy is regarded as the diagnostic gold standard, there are problems in its use for colonoscopic localization. Reliance on distance measurements may be misleading. Anatomical variants can be confusing. For this reason, a preoperative barium enema for precise delineation and localization of tumors is recommended. When a barium enema is not feasible, such as when a malignant polyp has been removed endoscopically, preoperative endoscopic localization with injection of India ink or intraoperative colonoscopy must be performed.

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

A mathematical model was used to estimate the cost-effectiveness of colorectal cancer screening strategies for people who are at high risk because of a first-degree relative with colorectal cancer. The model uses indirect evidence about such factors as cancer incidence, sensitivity and specificity of different tests, and treatment effectiveness. The analysis indicates that for screening people over 40 yr old an annual fecal occult blood test may reduce colorectal cancer mortality by about one-third, either colonoscopy or barium enema may reduce mortality by approximately 85%, a 3-5-yr frequency for endoscopies or barium enemas preserves 70%-90% of the effectiveness of an annual frequency, and beginning screening at age 50 reduces effectiveness by 5%-10%. Although both barium enemas and colonoscopies appear to be effective in reducing mortality, the lower cost of the barium enema makes it a more cost-effective strategy. All of these estimates depend on the baseline estimates of each of the factors incorporated in the model; the conclusions are most sensitive to assumptions about the natural history of adenomatous polyps, the bleeding of adenomas and presymptomatic cancers, and the sensitivity of the fecal occult blood test. Recommendations about colorectal cancer screening must also consider factors such as discomfort, inconvenience, and the availability of various technologies.

The workup of the asymptomatic patient with a positive fecal occult blood test

Twenty-two protocols for working up an asymptomatic patient who has a positive fecal occult blood test were evaluated using existing information on the prevalences of cancers, adenomas and other conditions in such patients; the natural history of colorectal cancer; the effectiveness of screening tests; risks; and costs. The authors estimate the impacts of the 22 workup strategies on outcomes such as the chance of finding an existing cancer or adenoma, risks (bleeding and perforation), and financial costs of different strategies involving rigid sigmoidoscopy, flexible sigmoidoscopy, barium enema, and colonoscopy. Two protocols were particularly effective. The first involves performing a barium enema study and following it with colonoscopy; if colonoscopy is negative, the barium enema study should be repeated. The second is to perform colonoscopy and if it is negative, follow it with a barium enema study.

The current status of early detection and screening for colorectal cancer

There are several approaches to the early detection of colorectal cancer that currently are in use in various segments of the health care system. Herein, the status of cancer control research regarding symptom and risk factor assessment, sigmoidoscopy and colonoscopy, double contrast barium enema, and fecal occult blood testing is reviewed. In addition to the different technologies of early cancer detection, there are different models of disease control intervention. These include the routine clinical activities of primary care providers as well as programmatic screening of mass populations. The currently available techniques for early colorectal cancer detection appear better suited for existing patient care settings than for programs outside the direct supervision and follow-up of the health professional.