Patient experience and preferences toward colon cancer screening: a comparison of virtual colonoscopy and conventional colonoscopy

Colonography by computed tomography

Computed tomographic colonography ('virtual colonoscopy') has shown promising results in the detection of large (> or = 10 mm) polyps in populations with a high prevalence of polyps. Recent studies in low prevalence populations, however, show variable results in sensitivity, ranging from 55% to 94% for the detection of patients with polyps measuring 10 mm or longer. Therefore questions have been raised about computed tomographic colonography as a screening method, probably the most valuable use of this technique. This article describes possible causes of these remarkable differences as well as advances in computed tomographic colonography.

Screening and surveillance of colorectal cancer

Although colorectal cancer (CRC) is the second leading cause of cancer deaths in the United States, it is preventable. Screening modalities include fecal occult blood testing, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. Colonoscopy allows effective detection and removal of precursor adenomatous polyps and is the dominant CRC screening modality. Emerging technologies include CT and MR colonography and fecal DNA tests. Effective and cost-effective surveillance after polypectomy and curative CRC resection requires balancing the protective effect of polypectomy while maximizing intervals between examinations; thus, estimation of the risk of recurrence determines the intensity of surveillance for individual patients.

Colon imaging: computed tomographic colonography

Computed tomographic colonography (CTC, virtual colonoscopy) is an attractive modality with which to image the colon. Many different techniques are available; moreover, during the last several years, advances in hardware and software have been remarkable. Evidence to this date suggests that CTC has varying sensitivity for detection of large colonic lesions, largely dependent on technique and the method of study. A variety of issues related to CTC are reviewed, including evolution of CTC, sensitivity and specificity of CTC, patient experience, extracolonic lesions, advances in colon preparation, and training. It is clear that CTC has great promise, but also that many questions about its use remain to be answered.

Mass screening with CT colonography: should the radiation exposure be of concern?

BACKGROUND & AIMS

Computed tomography colonography (CTC), particularly using noncathartic techniques, has the clear potential to increase compliance for colorectal cancer screening. Because the geometry for CTC is highly advantageous, it can be performed with lower radiation doses than almost any other CT examination. If CTC were to become a standard screening tool for the population age 50 years and older, the potential market in the United States would soon be over 100 million people. Therefore, it is pertinent to consider the radiation exposure and any potential radiation risk to the population from such a mass CTC screening program.

METHODS

Organ doses from CTC examinations can be estimated with standard techniques. These doses can be applied to organ- and dose-specific radiation cancer risk estimates to estimate the excess cancer risk resulting from the radiation from a paired (supine and prone) CTC examination.

RESULTS

The cancer risks associated with the radiation exposure from CTC are unlikely to be zero, but they are small. A best estimate for the absolute lifetime cancer risk associated with the radiation exposure using typical current scanner techniques is about 0.14% for paired CTC scans for a 50-year-old, and about half that for a 70-year-old. These values probably could be reduced by factors of 5 or 10 with optimized CTC protocols.

CONCLUSIONS

In terms of the radiation exposure, the benefit-risk ratio potentially is large for CTC.

Eliciting relative preferences for two methods of colorectal cancer screening

Two methods of mass population screening for colorectal cancer - faecal occult blood testing and sigmoidoscopy - have been the subject of randomized controlled trials in the UK. A national screening programme is currently under consideration and the choice of screening method remains open. To be successful, a programme will require high levels of uptake, and uptake is likely to depend upon subjects' attitudes towards the screening method introduced. Although a preferred screening method has already been identified from a questionnaire survey, we undertook a further interview study (n = 106), with a view to comparing the results of two different approaches to eliciting public preferences. In comparison with the questionnaire study, a higher proportion of interview subjects stated a preference. Interview subjects were generally more favourably disposed towards sigmoidoscopy, excepting those with previous experience. Compared with the questionnaire survey, the interviews provided richer information on the reasons for preferences offered. Individual preferences were evidently subjective and dependant on attitudes towards a variety of method characteristics, such as discomfort, convenience and perceived sophistication. Characteristics such as age and low income, which had predicted preferences in the questionnaire study, predicted preferences in the interview study also. The difference between the results obtained by the different elicitation techniques can be explained in terms of the differential provision of information and sample selection. Conclusions made about public preferences are likely to depend on the technique employed in eliciting them.

Dark lumen magnetic resonance enteroclysis in combination with MRI colonography for whole bowel assessment in patients with Crohn's disease: first clinical experience

BACKGROUND

Magnetic resonance enteroclysis (MRE) is a recently introduced imaging technique that assesses the small bowel with similar sensitivity and specificity as the fluoroscopically performed conventional enteroclysis. Magnetic resonance imaging colonography (MRC) seems to be a promising technique for polyp assessment in the colon. In this feasibility study, we evaluated the combination of small bowel MRI with unprepared MRC as an integrative diagnostic approach of the whole bowel in patients with Crohn's disease.

METHODS

Thirty patients with known Crohn's disease were prospectively examined. No particular colonic preparation was applied. Applying the dark lumen technique in all patients, MRE and MRC were performed within 1 session using an integrative examination protocol. T2-weighted and contrast-enhanced T1-weighted sequences were acquired. Inflammation assessment (grades 0 to 2) of the colon was compared with conventional colonoscopy in 29 patient and with surgery in 1 patient. The entire colon was graded fair to good distended in all patients. In 11 of 210 evaluated colonic segments, feces hindered an adequate intraluminal bowel assessment. Twenty-three of 30 patients had complete colonoscopy as the gold standard. In 7 patients, complete colonoscopy could not be performed because of an inflamed stenosis.

RESULTS

Correct grading of colonic inflammation was performed with 55.1% sensitivity and 98.2% specificity in all segments. Considering only more extensive inflammation (grade 2), the sensitivity of MRC increased to 70.2% with a specificity of 99.2%.

CONCLUSIONS

The combination of MRE and MRC could improve the diagnostic value of abdominal MRI evaluation in patients with Crohn's disease. However, MRC can not replace conventional colonoscopy in subtle inflammation assessment.

Intra-individual comparison of patient acceptability of multidetector-row CT colonography and double-contrast barium enema

AIMS

To compare the subjective acceptability of CT colonography in comparison with barium enema in older symptomatic patients, and to ascertain preferences for future colonic investigation.

MATERIALS AND METHODS

The study population comprised 78 persons aged 60 years or over with symptoms suggestive of colorectal neoplasia, who underwent CT colonography followed the same day by barium enema. A 25-point questionnaire was administered after each procedure and an additional follow-up questionnaire a week later. Responses were compared using Wilcoxon matched pairs testing, Mann-Whitney test statistics and binomial exact testing.

RESULTS

Participants suffered less physical discomfort during CT colonography (p = 0.03) and overall satisfaction was greater compared with barium enema (p = 0.03). On follow-up, respondents reported significantly better tolerance of CT colonography (p = 0.002), and were less prepared to undergo barium enema again (p < 0.001). Of 52 subjects expressing an opinion, all preferred CT to barium enema.

CONCLUSION

Patient satisfaction was higher with CT colonography than barium enema. CT colonography caused significantly less physical discomfort and was overwhelmingly preferred by patients.

Colorectal cancer screening and surveillance with CT colonography: current controversies and obstacles

Computed tomographic (CT) colonography has been advocated as an alternative colorectal screening method because studies in populations with a high prevalence of polyps have demonstrated that sensitivity for patients with large (> or =10 mm) polyps is generally high (approximately 90%). In three recent studies in low-prevalence populations, however, these values vary from 55% to 94%. Many questions have been raised as to the cause of this remarkable variability, which hampers the implementation of CT colonography in colorectal cancer screening and surveillance. We provide an overview of some potential causes and discuss the available, often indirect, evidence. In addition, several other obstacles that may influence implementation are discussed. Many differences between the study with high sensitivity (94%) and the two studies with low sensitivity (55% and 64%) exist: the primary method to review the data (two or three dimensional), bowel preparation (with or without oral contrast agents), study design (verification method and analysis of adenomas only), reader's experience, and scanning technique (single vs. multislice, thin vs. thick sections). Additional obstacles for implementation in prevention of colorectal cancer may be controversial results concerning patient acceptance, the large-scale use of ionizing radiation, difficulties in detecting flat adenomas, and extracolonic findings. Use of primary three-dimensional review methods, addition of oral contrast agents to bowel preparation, and endoscopic verification of false-positive results on CT colonography are speculated to have a positive influence on sensitivity. Future investigations should demonstrate the influence of these potential factors on sensitivity of CT colonography. Despite a growing body of evidence, it remains uncertain to what extent patient acceptance, radiation issues, flat lesions, and extracolonic findings will be a stumbling block to using CT colonography for colorectal cancer screening.

Magnetic resonance colonography: a promising new technique

Colorectal carcinoma is still the second leading cause of cancer-related death, although it arises mostly from benign adenomas. Numerous screening methods are available, but none of them is accepted as ideal. Ultrafast three-dimensional data sets acquired by cross-sectional imaging modalities (CT or magnetic resonance ) in combination with new post-processing modes, known as virtual colonoscopy, have led to a new discussion of screening tests for colorectal cancer. Recently published results indicate a high sensitivity for CT colonography and for MR-based colonography (MRC), with detection rates of greater than 90% for colorectal lesions greater than 10 mm in size. Three-dimensional data acquisition for MRC is performed in less than 1 minute, and no severe complications have been reported. The main advantages of MRC are the lack of ionizing radiation, the low risk of the procedure, and low patient discomfort. MRC has become an attractive diagnostic procedure for colorectal lesions that can also be used as a screening method.

Computerized tomography colonography

First introduced a decade ago, computerized tomography (CT) colonography (virtual colonoscopy) is emerging as an important radiologic investigation for colorectal neoplasia, with diagnostic performance likely exceeding barium enema and comparable with optical colonoscopy. Employing state-of-the-art multislice technology, CT colonography allows a complete examination of the colon and surrounding organs in less than 30 seconds. This article reviews current techniques, indications, comparison with existing technologies, and diagnostic performance. Although already widely disseminated, important future developments, such as prepless bowel cleansing (laxative free) and computer-aided diagnosis, may establish CT colonography as the preferred first-line, whole-colon investigation.

CT colonography and colonoscopy: assessment of patient preference in a 5-week follow-up study

PURPOSE

To prospectively evaluate short- and midterm patient preference of computed tomographic (CT) colonography relative to colonoscopy in patients at increased risk for colorectal cancer and to elucidate determinants of preference.

MATERIALS AND METHODS

Consecutive patients at increased risk for colorectal cancer underwent CT colonography prior to scheduled colonoscopy. Patient experience and preference were assessed both directly after the examinations and 5 weeks after the examinations. Differences in pain, embarrassment, discomfort, and preference were assessed with the Wilcoxon signed rank sum test or a binomial test. Potential determinants of preference were investigated with logistic regression analyses.

RESULTS

Data for 249 patients were included. Fewer patients experienced severe or extreme pain during CT colonography (seven [3%] of 245) than during colonoscopy (81 [34%] of 241) (P < .001). Directly after both examinations, 168 (71%) of 236 patients preferred CT colonography; 5 weeks later, 141 (61%) of 233 patients preferred CT colonography (P < .001). Initially, a painful colonoscopy examination (odds ratio, 0.17; 95% confidence interval [CI]: 0.08, 0.38) was a determinant of CT colonography preference. Similarly, a painful (odds ratio, 3.70; 95% CI: 1.54, 8.92) or an embarrassing (odds ratio, 4.46; 95% CI: 1.18, 16.88) CT colonography examination was a determinant of colonoscopy preference. After 5 weeks, the presence of polyps emerged as a determinant of colonoscopy preference (odds ratio, 1.94; 95% CI: 1.02, 3.70), while the role of experiences waned.

CONCLUSION

Patients preferred CT colonography to colonoscopy; however, this preference decreased in time, while outcome considerations gradually replaced temporary experiences of inconvenience.

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

BACKGROUND & AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Community-based screening by colonoscopy or computed tomographic colonography in asymptomatic average-risk subjects

OBJECTIVES

Visualizing the entire colorectum in screening is an advantage of colonoscopy, and also computed tomographic (CT) colonography, another potentially suitable screening test. Our objective was to compare screening CT colonography and colonoscopy in an asymptomatic average-risk population, and to determine whether providing a choice of tests increased participation.

METHODS

One thousand and four hundred subjects from the general community, randomly selected from the parliamentary electoral roll, were allocated one of three screening groups: colonoscopy, CT colonography, or a choice of these tests, and were sent an institutional letter of invitation. Those with symptoms, colorectal cancer in first-degree relatives, or colonoscopy within 5 yr were ineligible. Outcome measures were participation, acceptability of screening, and yield for advanced colorectal neoplasia in participants.

RESULTS

Of the subjects, 24.9% were ineligible; the overall participation rate was 18.2% (184/1,009). Participation in each screening group was not different. Both tests were accompanied by the same high levels of acceptability; most participants found colonoscopy (87%) and CT colonography (67%, p < 0.001) less unpleasant than expected. About 29% (26/89) CT colonography subjects had a positive screening test. The yield of advanced colorectal neoplasia was 8.7% (95% CI 5-14%), with no difference in yield between tests.

CONCLUSION

Colorectal neoplasia screening by colonoscopy or CT colonography was associated with modest participation, high levels of acceptability, and similar yield for advanced colorectal neoplasia. Providing a choice of test did not increase participation.

CT and MR colonography: scanning techniques, postprocessing, and emphasis on polyp detection

In the last decade, computed tomographic (CT) and magnetic resonance (MR) colonography, two new cross-sectional techniques for imaging of the colon, emerged. Both techniques show promising initial results in the detection of polyps equal to or greater than 1 cm in diameter in symptomatic patients. Imaging protocols are still mostly under development and prone to change. Both CT and MR colonography generate a large number of source images, which have to be read carefully for filling defects and, if intravenous contrast material is used, enhancing lesions. An important postprocessing technique is multiplanar reformatting, which allows the viewer to see potential lesions in an orientation other than that of the source images. Virtual endoscopy, a volume rendering technique that generates images from within the colon lumen, is used for problem solving. CT and MR colonography have potential advantages over colonoscopy and double-contrast barium enema examination: multiplanar capabilities, detection of enhancing lesions that make the distinction between fecal residue and true lesion possible, and ante- and retrograde virtual colonoscopy. Currently, a number of studies suggest that patients have a preference for CT colonography over colonoscopy. Patients consider bowel cleansing the most uncomfortable part of any colon examination; hence, from the acceptance point of view, fecal tagging techniques are promising. Before CT and MR colonography can be implemented in daily practice, they must show approximately the same accuracy as colonoscopy for polyp detection in both symptomatic and screening patients.

Magnetic resonance colonography in the detection of colonic neoplasm in high-risk and average-risk individuals

OBJECTIVES

Magnetic resonance colonography (MRC) is a new noninvasive diagnostic modality for colorectal cancer. However, the use of MRC in the detection of colorectal neoplasm in average-risk individuals remains unknown. This study determined the performance and the patient's preference of MRC in the detection of colorectal neoplasm.

METHODS

Both high-risk (i.e., symptoms suggestive of colorectal neoplasm, positive fecal occult blood test, history of colorectal cancer in one or more first-degree relatives) and average-risk (i.e., asymptomatic individuals >50 yr) individuals were recruited. MRC was performed immediately prior to conventional colonoscopy (CC) by using air inflation without contrast. The finding on CC together with histology was used as a gold standard. Patients' pain and discomfort score were recorded immediately and 24 h after the procedure. They were also asked about their preferences for the two procedures.

RESULTS

A total of 165 patients (79 average risk and 86 high risk) were recruited. Eight patients had incomplete MRC and one patient had failed CC. Of the remaining 156 patients, 4 were found to have colonic cancer and 31 were found to have 67 polyps. MRC correctly identified 3 cancers (sensitivity 75%, specificity 99.3%) and 4 patients with colonic polyps (sensitivity 12.9% and specificity 97.6%). Sensitivity of MRC tended to be lower in polyps <10 mm in size and in average-risk individuals. The mean procedure time of CC was significantly shorter than MRC (13.6 +/- 6.7 vs 20.6 +/- 2.7 min, p < 0.001). Although there was no significant difference in the pain and discomfort scores of the 2 procedures, 75% of patients preferred CC to MRC.

CONCLUSIONS

The performance of MRC when used in the detection of colonic neoplasm in average-risk individuals is unsatisfactory.

Colorectal neoplasia screening with CT colonography in average-risk asymptomatic subjects: community-based study

PURPOSE

To evaluate computed tomographic (CT) colonography as a screening tool for average-risk asymptomatic subjects with regard to participation, acceptability, and safety.

MATERIALS AND METHODS

CT colonography for colorectal neoplasia screening was offered to 2,000 subjects aged 50-54 and 65-69 years. Only asymptomatic subjects at average risk of colorectal neoplasia were enrolled. Participants underwent CT colonography followed by colonoscopy if CT colonography findings showed any polyps. Acceptability was measured with a 100-point (0, most favorable; 100, least favorable) visual analogue scale (VAS). Chi2 statistic was used to compare participation rates among subgroups. Safety of CT colonography was evaluated by recording all important adverse events.

RESULTS

A total of 1,452 subjects were eligible for screening. The adjusted participation rate was 28.4%. Participation was higher in younger subjects and in those from a high socioeconomic region. Major reasons for nonparticipation were insufficient time and perceived good health. Median VAS scores for pain, general satisfaction, embarrassment, and willingness to repeat screening were 13, 6, 8, and 5, respectively. Most subjects found CT colonography better than (60%) or same as (32%) expected. Ninety-three (27.4%) of 340 subjects were referred for colonoscopy, with polyps found in 67 (positive predictive value, 0.73). By adopting criteria that a positive finding at CT colonography is that of a single polyp larger than 5 mm or multiple polyps larger than 2 mm, 14% of CT examinations would have led to colonoscopy; 5.7% of CT findings were false-positive, with no significant impairment in large polyp detection. There were no important adverse events related to CT colonography, although four subjects had syncope or presyncope related to bowel preparation.

CONCLUSION

Community-based colorectal neoplasia screening with CT colonography was accompanied by a participation rate that compares favorably with that of similar screening programs. CT colonography was highly acceptable to participants.

Cardiovascular Effects at Multi–Detector Row CT Colonography Compared with Those at Conventional Endoscopy of the Colon

PURPOSE

To compare the cardiovascular effects of computed tomographic (CT) colonography and conventional endoscopy in a group of patients undergoing both procedures.

MATERIALS AND METHODS

A total of 144 patients underwent CT colonography followed by flexible sigmoidoscopy (40 patients) or colonoscopy (104 patients). Pulse, blood pressure, and oxygen saturation were measured before, during, and after the procedures. Forty patients also underwent continuous Holter electrocardiographic (ECG) monitoring. Periprocedural pain was assessed by using a handheld counting device. Outcome variables were assessed by using a combination of paired t testing and multilevel linear regression.

RESULTS

When a spasmolytic was not used, CT colonography was associated with only a small increase in oxygen saturation (P =.03), while use of a spasmolytic caused an increase in pulse (mean increase, 19.9 beats per minute; P <.001) and diastolic blood pressure (mean increase, 5 mm Hg; P <.001). Compared with that at CT, oxygen saturation decreased significantly during and after colonoscopy and sigmoidoscopy (mean decrease after colonoscopy with sedation, 1.0%; P <.001). Systolic and diastolic blood pressure also decreased during and after colonoscopy (mean systolic decrease after colonoscopy with sedation, 16.6 mm Hg, P <.001; mean diastolic decrease after colonoscopy with sedation, 7.5 mm Hg, P <.001). Patients were 30.3 times more likely to develop bradycardia after endoscopy (95% CI: 2.65, 346; P =.006). Ventricular couplets were significantly higher at endoscopy than at CT in patients with a history of cardiac disease (odds ratio: 72.5 and 95% CI: 4.56, 1,153 at CT vs odds ratio: 14.6 and 95% CI: 0.96, 222 at endoscopy; P =.002). Patients were 1.89 times more likely to register pain during colonoscopy than during CT (95% CI: 1.06, 3.38; P =.03).

CONCLUSION

CT colonography had no significant cardiovascular effect other than spasmolytic-induced tachycardia. Endoscopy-and colonoscopy in particular-causes cardiovascular effects that are largely related to sedation. CT colonography is less painful than colonoscopy and is comparable to flexible sigmoidoscopy.

Acceptance by patients of multidetector CT colonography compared with barium enema examinations, flexible sigmoidoscopy, and colonoscopy

OBJECTIVE

The purpose of this study was to compare patient acceptance of multidetector CT colonography, total colonoscopy, flexible sigmoidoscopy, and double-contrast barium enema to ascertain any overall preference. SUBJECTS AND METHODS. One hundred sixty-eight patients underwent CT colonography followed by either flexible sigmoidoscopy (n = 59) or colonoscopy (n = 109). A 25-point questionnaire with principal components relating to satisfaction, worry, and physical discomfort was administered after CT colonography and after endoscopy, and a follow-up questionnaire was administered 1 week after the procedures. Questionnaires were also completed by 140 patients undergoing double-contrast barium enema examinations. Responses were compared using Wilcoxon's matched pairs test and the Mann-Whitney test.

RESULTS

Overall satisfaction was greater with colonoscopy (p = 0.01), but CT colonography caused less discomfort (p = 0.002), was better tolerated (p = 0.005), and was the preferred follow-up investigation of those expressing a preference (p = 0.003). Compared with flexible sigmoidoscopy, CT colonography caused less pain (p = 0.004), was more acceptable (p = 0.04), and was preferred as the follow-up investigation (p < 0.001). Tolerance of colonoscopy was significantly less in women (p = 0.03), but such was not the case for CT colonography (p = 0.58). Patients undergoing CT colonography were less worried (p < 0.001), were more satisfied (p = 0.001), and suffered less discomfort (p < 0.001) than those having barium enema.

CONCLUSION

Patients' experiences with barium enema examinations were significantly worse than with any other test. Although patients were most satisfied with colonoscopy, they reported more pain during both colonoscopy and sigmoidoscopy than during CT colonography, and they also found CT more acceptable. In patients expressing a preference, CT colonography was the preferred follow-up investigation.

Virtual colonoscopy compared with conventional colonoscopy for stricturing postoperative recurrence in Crohn's disease

BACKGROUND

The place of virtual colonoscopy (VC) in patients with Crohn's disease (CD) requiring endoscopic follow-up after surgery is unknown. The authors compared findings from VC versus conventional colonoscopy (CC) for assessing the postoperative recurrence of CD.

METHODS

Sixteen patients with ileocolonic anastomosis for CD were prospectively enrolled from January 2001 to January 2002. Recurrence was assessed by CC according to Rutgeerts et al. VC was performed with a computed tomography scanner, with images examined by three radiologists who were unaware of the endoscopic findings.

RESULTS

CC showed perianastomotic recurrence in 15 of 16 patients. Perianastomotic narrowing or stenosis was detected by VC in 11 of these 15 patients. There were 11 true positive, 1 true negative, 0 false-positive, and 4 false-negative findings (73% sensitivity, 100% specificity, 100% positive predictive value, 20% negative predictive value, 75% accuracy). Among the eight patients showing a rigid stenosis of the anastomosis not allowing passage of the colonoscope, VC detected narrowing or stenosis in seven patients.

CONCLUSIONS

The current findings suggest that although the widespread use of VC in CD is currently not indicated because of possible false-negative findings, this technique may represent an alternative to CC in noncompliant postsurgical patients with a rigid stenosis not allowing passage of the endoscope.

Is colonoscopic screening of a low-risk (normal) population ethically justifiable?

This report summarizes the arguments for and against colonoscopic screening of a low-risk population for colorectal cancer. The strongest argument in favor of colonoscopy is that colonoscopy rarely misses an existing colorectal neoplasia and its precursor lesions and that procedural side effects are rare. In contrast, the combination of fecal occult blood test plus sigmoidoscopy leaves 10-15% of advanced neoplasms in the proximal colon undetected. However, colonoscopy is costly and the health care systems of only few European countries refund the respective costs. In addition, there is presently not sufficient manpower available to deliver colonoscopy to the public starting at the age of 50 in a 1:10 yearly frequency. Compliance to the procedure is very low even in countries which refund screening costs. Therefore, promotion of colonoscopy as the presently most effective screening procedure depends mainly on major educational efforts within the public to increase compliance as well as on the readiness of European health care systems to cover the respective costs.

Colorectal cancer screening with CT colonography, colonoscopy, and double-contrast barium enema examination: prospective assessment of patient perceptions and preferences

PURPOSE

To prospectively assess and compare perceptions of and preferences for computed tomographic (CT) colonography, colonoscopy, and double-contrast barium enema examination (DCBE) by asymptomatic patients undergoing colorectal cancer screening.

MATERIALS AND METHODS

A total of 696 asymptomatic patients at higher-than-average risk undergoing colorectal cancer screening were consecutively recruited to undergo both CT colonography and colonoscopy (group 1), and a like group of 617 patients was separately recruited to undergo both CT colonography and DCBE (group 2). Standard bowel preparations were different between the groups undergoing colonoscopy and DCBE. Each patient completed a questionnaire that assessed preparation inconvenience and discomfort, examination discomfort, willingness to repeat examinations, and examination preference. Survey results were compared for significance by using the Wilcoxon rank sum or chi2 test.

RESULTS

The majority of patients considered the preparation to be uncomfortable (group 1, 460 of 515 [89%]; group 2, 482 of 538 [90%]) and inconvenient (group 1, 393 of 502 [78%]; group 2, 427 of 527 [81%]). Reported discomfort was similar at CT colonography and colonoscopy (P =.63) but was less at CT colonography than at DCBE (P <.001). Patients experienced significantly less discomfort than expected at both CT colonography and colonoscopy but not at DCBE. Patients' willingness to undergo frequent rescreening was significantly greater for CT colonography than for either colonoscopy or DCBE. The acceptable time interval between screenings was significantly shorter for all examinations if the bowel preparation could be avoided. Overall, patients preferred CT colonography to colonoscopy (group 1, 72.3% vs 5.1%; P <.001) or to DCBE (group 2, 97.0% vs 0.4%; P <.001).

CONCLUSION

Patients undergoing colorectal cancer screening prefer CT colonography to both colonoscopy and DCBE. The majority of patients experience discomfort and inconvenience with cathartic bowel preparation.

Colorectal cancer screening: scientific review

CONTEXT

Screening for colorectal cancer clearly reduces colorectal cancer mortality, yet many eligible adults remain unscreened. Several screening tests are available, and various professional organizations have differing recommendations on which screening test to use. Clinicians are challenged to ensure that eligible patients undergo colorectal cancer screening and to guide patients in choosing what tests to receive.

OBJECTIVE

To critically assess the evidence for use of the available colorectal cancer screening tests, including fecal occult blood tests, sigmoidoscopy, colonoscopy, double-contrast barium enema, and newer tests, such as virtual colonoscopy and stool-based molecular screening.

DATA SOURCES

All relevant English-language articles were identified using PubMed (January 1966-August 2002), published meta-analyses, reference lists of key articles, and expert consultation.

DATA EXTRACTION

Studies that evaluated colorectal cancer screening in healthy individuals and assessed clinical outcomes were included. Evidence from randomized controlled trials was considered to be of highest quality, followed by observational evidence. Diagnostic accuracy studies were evaluated when randomized controlled trials and observational studies were not available or did not provide adequate evidence. Studies were excluded if they did not evaluate colorectal screening tests and if they did not evaluate average-risk individuals.

DATA SYNTHESIS

Randomized controlled trials have shown that fecal occult blood testing can reduce colorectal cancer incidence and mortality. Case-control studies have shown that sigmoidoscopy is associated with a reduction in mortality, and observational studies suggest colonoscopy is effective as well. Combining fecal occult blood testing and sigmoidoscopy may decrease mortality and can increase diagnostic yield.

CONCLUSION

The recommendation that all men and women aged 50 years or older undergo screening for colorectal cancer is supported by a large body of direct and indirect evidence. At present, the available evidence does not currently support choosing one test over another.

Patient preferences for CT colonography, conventional colonoscopy, and bowel preparation

OBJECTIVES

The aim of this study was to determine patient pre-examination expectations and postexamination appraisals for CT colonography, conventional colonoscopy and bowel preparation.

METHODS

Prospective evaluation of 120 patients at defined risk for colorectal neoplasia was performed with CT colonography followed by colonoscopy on the same day. Subjects were stratified by age and sex (67 women and 53 men) and were randomized to receive either manual air (n = 61) or CO(2) (n = 59) insufflation during CT colonography. Patients' expectations were assessed just before the two examinations, and appraisals were assessed 2 to 3 days afterward regarding pain/discomfort, embarrassment, difficulty, overall assessment, preference for future testing, and bowel preparation.

RESULTS

No significant differences were found in appraisals of manual air versus CO(2) insufflation techniques. For both CT colonography and colonoscopy, patients' appraisals after the procedure were significantly more positive than prior expectations. Patients expressed more favorable appraisals of colonoscopy for pain (p < 0.001) and embarrassment (p < 0.001), with most responses being "none" to "a little" for both examinations. Overall appraisals of the tests were favorable and similar between CT and colonoscopy: patients mainly expressed "not unpleasant" to "a little unpleasant" (95%, 114/120 for both examinations). Overall, appraisal of the bowel preparation was the most negative. Preferences for future testing were more favorable toward CT: of the patients, 58% (69/120) preferred CT, 14% (17/120) preferred colonoscopy, and 28% (34/120) had no preference.

CONCLUSIONS

Overall appraisals were similar and positive for both CT colonography and colonoscopy, with less favorable appraisals of the bowel preparation. Most patients stated that they would prefer CT for future evaluation.

Screening CT colonography

CT colonography (Virtual Colonoscopy) was first introduced in 1994 as a novel imaging technique for the detection of colorectal polyps and cancer. It is currently proposed as a new screening tool for colorectal carcinoma that may be more acceptable to patients than current methods. There are a growing number of published studies evaluating all aspects of CT colonography, including technique, imaging displays, interpretation methods, patient acceptance, and lesion detection accuracy. While there are multiple studies that have found excellent CT colonography results for the detection of larger polyps in high risk or symptomatic patient cohorts, there are very few published studies evaluating the performance of CT colonography in asymptomatic screening patients. Although we do not have the results of large, randomized, controlled trials documenting the performance of CT colonography in screening-type patients, this technique is currently employed at some sites as a screening tool for colorectal carcinoma. Thus, CT colonography has become a part of the controversy surrounding total body CT screening. In this article, the current techniques for colonic preparation and distention will be discussed, as well as the optimum CT protocol, and the recommended use of image displays for time-efficient interpretation. The results of the larger and newer studies will be presented, as well as some of the current clinical uses of CT colonography. Issues specific to the use of CT colonography as a screening test will also be discussed.

Colorectal cancer screening: a challenge for magnetic resonance colonography

The high incidence of colorectal carcinoma and the fact that colorectal cancer mostly arises from benign adenomas have led to recommendations for screening programs. The introduction of ultrafast three-dimensional datasets acquired by cross-sectional imaging modalities (computed tomography or magnetic resonance imaging) in combination with new postprocessing modes, known as virtual endoscopy, has led to new discussion on the recommendation of screening tests for colorectal cancer. Published results have indicated a high sensitivity for computed tomographic colonography and magnetic resonance-based colonography. Both techniques currently must be combined with colon cleansing. Three-dimensional data acquisition for magnetic resonance-based colonography is less than 1 minute using three-dimensional gradient-echo sequences. The lack of ionizing radiation, the low risk and discomfort to patients, and new techniques of minimized patient preparation make this magnetic resonance technique an attractive diagnostic procedure for colorectal lesions, with many aspects for use as a screening method.

The future of colorectal imaging: computed tomographic colonography

The development of colorectal cancer screening alternatives that are attractive to patients and effective for screening is critical for reducing this too-common and deadly disease. CTC is an exciting technique that is the only imaging alternative developed since the barium enema for colon screening. In the past few years, many obstacles to clinical implementation of CTC have been eliminated. For example, there is no longer any post-processing time, which was previously as long as 8 to 10 hours, and the interpretation time has been drastically reduced from 4 hours to 15 to 20 minutes. The majority of studies have demonstrated excellent results for detection of lesions > or = 1 cm, with few false positives. This examination will continue to improve with the development of automated (computer) detection programs and automated 3D rendering algorithms. In addition, cathartic bowel preparation, one of the biggest obstacles to patient compliance with colorectal cancer screening, may be eliminated if successful fecal tagging can be developed. The most important issue that remains is its performance in a screening population, and studies are currently underway to answer that important question.

Colon cancer screening strategies

Screening has been shown to reduce morbidity and mortality related to colorectal cancer. However, the optimal strategy for population screening for colorectal cancer has been a topic of heated debate. Recent studies have challenged the efficacy and cost-effectiveness of current population screening practices. Novel approaches to improve the assessment of an individual's colorectal cancer risk and advances in technology are changing our approach to colorectal screening. This review covers current guidelines for screening for colorectal cancer, recent advances in cancer risk assessment, and the role of endoscopy, virtual colonoscopy, and fecal DNA testing in colorectal cancer screening.