CT colonography before colonoscopy in subjects with positive faecal occult blood test. Preliminary experience

Purpose

We report a preliminary evaluation of the performance of computed tomography colonography (CTC) systematically obtained before optical colonoscopy (OC) in subjects with positive faecal occult blood test (FOBT) within a population-based screening programme for colorectal cancer (CRC).

Materials and methods

Seventy-nine subjects with positive FOBT from a regional screening programme were invited to perform same day CTC and OC. CTC was performed with standard bowel preparation. OC with segmental unblinding was the reference standard. A perpatient per-adenoma analysis was performed.

Results

Forty-nine of 79 subjects (62%) with positive FOBT adhered to the study and completed both examinations. Twenty-two (44.9%) of the 49 had a cancer or an adenoma ≥6 mm. Per-patient sensitivity, specificity, negative predictive value and positive predictive value for cancer or adenoma ≥6 mm were 95.5% (95%CI:77.2%–99.9%), 51.9% (95%CI:32.0%–71.3%), 93.3% (95%CI:68.1%–99.8%) and 61.8% (95%CI:43.6%–77.8%).

Conclusions

In the setting of a FOBT-based screening programme for CRC, CTC showed a high sensitivity, but relatively low specificity and positive predictive value, for cancer and adenoma ≥6 mm. Probably performing CTC without faecal tagging as second line test after a positive FOBT is not a cost-effective strategy.     

某部40岁以上1208例体检人群大肠癌筛查结果分析

 目的 探索与体检相结合的大肠癌筛查工作的可行性。方法 选择某部40岁以上人群1208例,通过宣传手段使其了解大肠癌的危险因素,发放便潜血标本收集器,对便潜血试验阳性和有危险因素的高危人群进行肠镜检查。结果 在1208例筛查人员中,同时行便潜血检查和参加危险因素调查者1045例,筛查的总应答率86.5%,肠镜检查的应答率72.7%,均高于国内几次大型筛查的应答率（P＜0.05）。潜血阳性组行肠镜检查21例,危险因素调查阳性组行肠镜检查83例;两组的肠镜检查应答率、肠镜检查阳性率、癌的检出率、伴不典型增生的检出率相比差异无统计学意义,潜血阳性组绒毛状腺瘤、多发管状腺瘤的检出率高于危险因素调查阳性组（P＜0.05）,危险因素调查阳性组单发管状腺瘤的检出率高于潜血阳性组（P＜0.05）。结论 与单位体检相结合的大肠癌筛查方案人群应答率高,危险因素调查是大肠癌筛查的有效手段。     

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.     

Detection of colorectal cancer and adenomas by FDG-PET cancer screening program: results based on a nationwide Japanese survey

Purpose

The aim of this study was to analyze the detection rate for CRC and adenomas for asymptomatic subjects in Japan by FDG-PET cancer screening program carried out between 2006 and 2009.

Methods

The “FDG-PET cancer screening program” included both PET and positron emission tomography with computed tomography (PET/CT) with or without other screening tests. A total of 154,783 asymptomatic subjects underwent FDG-PET cancer screening program; we analyzed the 1,808 cases with findings from any detection method that indicated suspected CRC.

Results

Among the 1,808 cases, the number of cases verified as CRC and adenoma was 394 and 679, respectively. The sensitivity and positive predictive value (PPV) of FDG-PET were 86.0 and 31.7 % for CRC, and 63.6 and 63.8 % for CRC and adenoma. The sensitivity and PPV of fecal occult blood test (FOBT) for CRC were lower than those of FDG-PET, but higher for adenoma. Therefore, FDG-PET and FOBT were complementary for screening for CRC, and CRC and adenoma. The majority of CRC detected by the FDG-PET imaging was UICC stage 0 or I, however, detection of smaller or less invasive cancer was limited.

Conclusion

The FDG-PET screening program in Japan has detected CRC at an early stage and adenomas as premalignant lesions. A combination of FDG-PET and FOBT yields the best results if the intent is to detect either CRC or adenoma. However, it is absolutely clear that an FDG-PET cancer screening program cannot detect all colon lesions.     

Cost-effectiveness modeling of colorectal cancer: computed tomography colonography vs colonoscopy or fecal occult blood tests

Objectives

To assess the cost-effectiveness of three colorectal-cancer (CRC) screening strategies in France: fecal-occult-blood tests (FOBT), computed-tomography-colonography (CTC) and optical-colonoscopy (OC).

Methods

Ten-year simulation modeling was used to assess a virtual asymptomatic, average-risk population 50–74 years old. Negative OC was repeated 10 years later, and OC positive for advanced or non-advanced adenoma 3 or 5 years later, respectively. FOBT was repeated biennially. Negative CTC was repeated 5 years later. Positive CTC and FOBT led to triennial OC. Total cost and CRC rate after 10 years for each screening strategy and 0–100% adherence rates with 10% increments were computed. Transition probabilities were programmed using distribution ranges to account for uncertainty parameters. Direct medical costs were estimated using the French national health insurance prices. Probabilistic sensitivity analyses used 5000 Monte Carlo simulations generating model outcomes and standard deviations.

Results

For a given adherence rate, CTC screening was always the most effective but not the most cost-effective. FOBT was the least effective but most cost-effective strategy. OC was of intermediate efficacy and the least cost-effective strategy. Without screening, treatment of 123 CRC per 10,000 individuals would cost €3,444,000. For 60% adherence, the respective costs of preventing and treating, respectively 49 and 74 FOBT-detected, 73 and 50 CTC-detected and 63 and 60 OC-detected CRC would be €2,810,000, €6,450,000 and €9,340,000.

Conclusion

Simulation modeling helped to identify what would be the most effective (CTC) and cost-effective screening (FOBT) strategy in the setting of mass CRC screening in France.     

Computed tomography colonography for the practicing radiologist: A review of current recommendations on methodology and clinical indications

Colorectal cancer (CRC) represents one of the most relevant causes of morbidity and mortality in Western societies. CRC screening is actually based on faecal occult blood testing, and optical colonoscopy still remains the gold standard screening test for cancer detection. However, computed tomography colonography (CT colonography) constitutes a reliable, minimally-invasive method to rapidly and effectively evaluate the entire colon for clinically relevant lesions. Furthermore, even if the benefits of its employment in CRC mass screening have not fully established yet, CT colonography may represent a reasonable alternative screening test in patients who cannot undergo or refuse colonoscopy. Therefore, the purpose of our review is to illustrate the most updated recommendations on methodology and the current clinical indications of CT colonography, according to the data of the existing relevant literature.     

Does CT colonography have a role for population-based colorectal cancer screening?

Colorectal cancer (CRC) is the second most common cancer and second most common cause of cancer-related deaths in Europe. CRC screening has been proven to reduce disease-specific mortality and several European countries employ national screening programmes. These almost exclusively rely on stool tests, with endoscopy used as an adjunct in some countries. Computed tomographic colonography (CTC) is a potential screening test, with an estimated sensitivity of 88?% for advanced neoplasia ≥10?mm. Recent randomised studies have shown that CTC and colonoscopy have similar yields of advanced neoplasia per screened invitee, indicating that CTC is potentially viable as a primary screening test. However, the evidence is not fully elaborated. It is unclear whether CTC screening is cost-effective and the impact of extracolonic findings, both medical and economic, remains unknown. Furthermore, the effect of CTC screening on CRC-related mortality is unknown, as it is also unknown for colonoscopy. It is plausible that both techniques could lead to decreased mortality, as for sigmoidoscopy and gFOBT. Although radiation exposure is a drawback, this disadvantage may be over-emphasised. In conclusion, the detection characteristics and acceptability of CTC suggest it is a viable screening investigation. Implementation will depend on detection of extracolonic disease and health-economic impact. Key Points ? Meta-analysis of CT colonographic screening showed high sensitivity for advanced neoplasia ≥10mm. ? CTC, colonoscopy and sigmoidoscopy screening all have similar yields for advanced neoplasia. ? Good quality information regarding the cost-effectiveness of CTC screening is lacking. ? There is little good quality data regarding the impact of extracolonic findings. ? CTC triage is not clinically effective in first round gFOBT/FIT positives.     

Virtual colonoscopy--chances for a screening procedure?

In principle, virtual colonoscopy is capable to be used as method for early detection of colorectal cancer (CRC), even if the accuracy of the method and radiation exposure are matters discussion in the radiological community. Virtual colonoscopy is able to detect any pathology which is relevant for early detection of CRC especially when using multislice CT, but also with single slice CT. The diagnosis of small lesions, less than 7 mm in diameter (polyps and flat lesions) is still problematic as it is in conventional colonoscopy. The exposure to x-rays in asymptomatic patients, without any increased risk of developing cancer is highly problematic and should be reduced to a minimum. Using special post processing filters on the volume dataset it can be shown that a tube current of 20 mAs is sufficient without any loss in accuracy. Measurements on the Alderson-phantom showed, that an effective dose exposure of 1.2 mSv is obtained using these reduced mAs values. It has to be differentiated between virtual colonoscopy for early detection of polyps and CRC in individual patients or as a screening examination of a large population. Virtual colonoscopy as a screening examination necessitates reduction of radiation dose, a high degree of automatization in 3D reconstructions as well as the assessment of the entire mucosa. High risk patients, whom refuse fibreoptic colonoscopy should undergo virtual colonoscopy. Virtual colonoscopy has a good chance to become an accepted tool for general screening, if efficient dose reduction, complete visualization of the colon mucosa and automatization of the post processing procedures can be achieved.     

Screening des Kolonkarzinoms

Colorectal cancer (CRC) is responsible for 27,000 deaths and 65,000 new cancers in Germany each year, although this should be unnecessary as CRC is preventable because it is possible to remove the precursors, harmless polyps and adenomas. However, only 2.5?% of people in health insurance make use of screening colonoscopy annually so that it becomes necessary to check out other screening tests. The most commonly used test is the Guaiak-based test for fecal occult blood (gFOBT) which is highly specific but not very sensitive (only approximately 10?%). New immunological stool tests are more sensitive but the specificity is reduced from 90?% to approximately 80?%. Virtual colonoscopy based on computed tomography (CT) or magnetic resonance imaging (MRI) is comparable to endoscopy for diagnostics with overall accuracy rates of approximately 80–90?% for polyps larger than 5 mm but for radiation protection reasons CT is not usable in Germany and MRI is internationally not adequately established by large study trials. For the future there is much hope in molecular blood tests. It is of great importance that every physician is aware of the different tests, their strengths and weaknesses and advises all patients to use the different screening possibilities.     

应用纤维结肠镜进行直肠乙状结肠癌普查的探讨(附4219例分析)

在4219人普查中,共检出大肠癌5例(0.1％),其中Dukse A期早期癌2例、B期癌2例、C期癌1例。检出大肠息肉160例(3.8％),其中腺瘤86例,有3例重度不典型增生。所有息肉均经内镜切除。作者意见:小组人群可直接用纤维结肠镜普查;大组人群普查最好先经隐血试验初筛,阳性者及阴性的高危人群再做纤维结肠镜检查。术前不进行饮食准备,清洗肠道提倡用开塞露灌肠。     

Completion of colorectal cancer screening in women attending screening mammography

RATIONALE AND OBJECTIVES: The American Cancer Society (ACS) and the United States Preventive Services Task Force (USPSTF) recommend colorectal cancer (CRC) screening to begin at age 50 in individuals at average risk for CRC. To estimate rate at which women eligible for CRC screening at the time of screening mammography attendance later completed in CRC screening, we retrospectively evaluated CRC screening utilization in women who underwent screening mammography at our institution. MATERIALS AND METHODS: We retrospectively identified 3357 women between the ages of 50 to 75 who received screening mammography in 1998 at a single academic medical center using the institution's Radiology Information System (RIS). Additional information collected from the institution's Health System Data Warehouse and the Radiology department's mammography quality assurance data included mammography results, Breast Imaging Reporting and Database System (BI-RADS) classification of mammography findings, recommendation for screening mammography follow-up, insurance status, and CRC screening utilization after screening mammography. After excluding women who were current with CRC screening at the time of mammography, we determined the proportion of eligible women who completed CRC screening after mammography. Age, insurance type, BI-RADS code, and recommendation code were evaluated as potential predictors of CRC screening completion in eligible women. RESULTS: Of the 3357 women between the ages of 50 and 75 who received screening mammography in 1998, only 414 (12.3%) were current with CRC screening at the time of screening mammography. Of the remaining 2943 women who were eligible for CRC screening at the time of screening mammography, 142 (4.8%) subsequently completed CRC screening. Average time to completion of CRC screening after screening mammography is 35.4 months (range, 0.27-64.9). Managed care insurance was the only significant predictor of CRC screening completion after screening mammography in eligible women after adjusting for other variables (adjusted OR 1.73, 95% CI 1.21-2.47, P < .0001). Neither BI-RADS classification nor postmammography recommendations were significantly associated with CRC screening completion. CONCLUSIONS: Prevalence studies have demonstrated that women who were compliant with screening mammography were more compliant with CRC screening. Our data suggest that despite this increased compliance, overall incidence of CRC screening is low in the screening mammography population.     

An international review of the main cost-effectiveness drivers of virtual colonography versus conventional colonoscopy for colorectal cancer screening: Is the tide changing due to adherence?

Objectives

The majority of recent cost-effectiveness reviews concluded that computerised tomographic colonography (CTC) is not a cost-effective colorectal cancer (CRC) screening strategy yet. The objective of this review is to examine cost-effectiveness of CTC versus optical colonoscopy (COL) for CRC screening and identify the main drivers influencing cost-effectiveness due to the emergence of new research.

Methods

A systematic review was conducted for cost-effectiveness studies comparing CTC and COL as a screening tool and providing outcomes in life-years saved, published between January 2006 and November 2012.

Results

Nine studies were included in the review. There was considerable heterogeneity in modelling complexity and methodology. Different model assumptions and inputs had large effects on resulting cost-effectiveness of CTC and COL. CTC was found to be dominant or cost-effective in three studies, assuming the most favourable scenario. COL was found to be not cost effective in one study.

Conclusions

CTC has the potential to be a cost-effective CRC screening strategy when compared to COL. The most important assumptions that influenced the cost-effectiveness of CTC and COL were related to CTC threshold-based reporting of polyps, CTC cost, CTC sensitivity for large polyps, natural history of adenoma transition to cancer, AAA parameters and importantly, adherence. There is a strong need for a differential consideration of patient adherence and compliance to CTC and COL. Recent research shows that laxative-free CTC screening has the potential to become a good alternative screening method for CRC as it can improve patient uptake of screening.     

低剂量CT仿真结肠镜结合FOBT检查对结直肠癌的诊断价值

目的探讨低剂量CT仿真结肠镜结合增强扫描(CTVC)及大便潜血检测(fecal occult blood test,FOBT)诊断结直肠癌临床价值。方法选取我院160例结肠占位性病变患者作为观察对象,均行CTVC及FOBT,分析低剂量CTVC、FOBT的临床效果。结果病理学结果显示,160例结直肠占位性病变中,93例为结直肠癌、67例为良性病变。结肠镜阳性检出78例、阴性检出54例,常规CT检出91例、阴性检出58例,低剂量CTVC阳性检出91例、阴性检出58例,结肠镜、常规CT、CTVC与病理学结果的Kappa值分别为0.682、0.857、0.857;此外,低剂量CTVC组同常规剂量组比较,其放射剂量长度乘积(DLP)、有效放射剂量(ED)均显著下降。FOBT阳性检出84例、阴性检出66例,与病理学结果的Kappa值为0.874。低剂量、FOBT的曲线下面积(ACU)、特异度分别为0.922、0.944、0.978、0.683,2者联合的ACU、特异度为0.987、0.989。结论FOBI辅助低剂量CTVC能够提高对结肠癌的诊断效果,且降低患者的辐射剂量,值得临床推广应用。     

Diagnostic accuracy of CT colonography in patients with positive faecal occult blood test: results of the Italian project Legatumori 2003–2006

Purpose

In the framework of the 3-year project of the Italian Legatumori (2003–2006), we evaluated the diagnostic accuracy of computed tomography (CT) colonography in detecting colorectal lesions in a screening population with positive faecal occult blood test (FOBT).

Materials and methods

Two hundred and thirty asymptomatic subjects (age range 45–80 years) were enrolled in the study. CT colonography was performed with standard patient preparation (no faecal tagging) and a 4-detector-row CT scanner. Image analysis was carried out with primary 2D analysis and the use of 3D endoluminal views to solve difficult cases. Patients were referred for conventional colonoscopy in the following situations: detection of three or more suspected lesions with maximum diameter ≤6 mm; evidence of one or more lesions with maximum diameter >6 mm; presence of colonic masses (maximum diameter >3 cm).

Results

CT colonography detected colonic masses in 12 out of 135 subjects (8%). It generated 93 false positives and 19 false negatives in the identification of diminutive lesions (≤6 mm), and 70 false positives and six false negatives in lesions >6 mm. Sensitivity was 83% in smaller lesions and 93% in lesions >6 mm; specificity was 45% and 59%, respectively.

Conclusions

In a screening population with positive FOBT, CT colonography without faecal tagging and no definite size threshold for the reporting of polyps showed very low specificity but high sensitivity in the detection of all colorectal lesions.     

An evaluation of current methods of diagnosing colorectal cancer in the United Kingdom

Colorectal cancer (CRC) is a highly conversed topic, particularly since implementation of screening for CRC is imminent within the U.K.AimsThe aim of this research project was to examine the diagnostic tools currently used within the UK to detect CRC and their impact on the aetiology and epidemiology of CRC.MethodologyThe complexity of the research topic lent itself towards a literature review. A systematic approach of researching was therefore adopted to analyse and critically evaluate the reliability and validity of articles. Electronic databases including AMED, Cancerlit, CINHAL, the Cochrane Library, EMBASE, MEDLINE and EBM-Reviews were utilised to provide a wide spectrum of recent and relevant articles. Other research strategies involved looking for books relating to the topics, which were kept to within 6 years of publication to maintain accuracy of information. Selected websites, such as NICE, the Department of Health, NHS websites and Cancer Research U.K. were useful at explaining current and future screening plans and trials within Britain and allowed the study of reliable U.K. statistics. The research articles were then outlined and placed into sections of similar topic areas, which enabled the author to compare, contrast and evaluate the hypotheses. By organising the research in this way, a thorough review of the existing research for CRC was resultant.ResultsA range of diagnostic tools is currently in use for detecting CRC within the UK. Screening for asymptomatic individuals aged 55–60 years+, (the age range where CRC incidence is higher), would provide the most effective reduction in CRC incidence and mortality rates.ConclusionsThe use of a multi-phasic screening programme consisting of faecal occult blood tests (FOBt) and a whole bowel examination is considered to be the most effective diagnostic tools. However, preventative schemes, such as better education of the risks and symptoms of CRC, supported by the NHS Cancer Plan (2000), have demonstrated to be a vital adjunct to CRC screening to reduce the incidence and mortality of the disease.     

Associations in breast and colon cancer screening behavior in women

RATIONALE AND OBJECTIVES: Gender-based psychosocial factors appear to influence colorectal cancer (CRC) screening adherence. Given its near-universal acceptance by the public, screening mammography represents a potential "teachable moment" for educating patients about the risk of CRC. Accordingly, to better understand screening behaviors among women, data from the Behavioral Risk Factors Surveillance Survey (BRFSS) were analyzed to identify potential relationships that would allow interventions to enhance CRC screening. MATERIALS AND METHODS: Women 50 years and older who participated in the BRFSS 2001 survey were included in the analysis. Colorectal, breast, and cervical cancer screening adherence with American Cancer Society guidelines was determined. We identified the association between breast and cervical cancer screening adherence and general health and demographic characteristics with CRC screening adherence. RESULTS: After adjustment for sociodemographic factors in a multivariate analysis, women 60-69 years old (adjusted odds ratio [OR], 1.50; P < .01) and 70-79 years old (adjusted OR, 1.39; P < .01), having achieved at least some high school (adjusted OR, 1.62; P < .01) or college (adjusted OR, 2.11; P < .01) education, having health coverage (adjusted OR, 1.67; P < .01) or a personal physician (adjusted OR, 1.60; P < .01), and adherence to screening mammography (adjusted OR, 2.42; P < .01) and Pap smear (adjusted OR, 1.70; P < .01) were independently associated with an increased likelihood CRC screening adherence. Women in self-reported good general health were less likely to have adhered to CRC screening guidelines (adjusted OR, 0.79; P < .01). Current smokers were also less likely to have adhered to CRC screening guidelines than were women who never smoked or formerly smoked (adjusted OR, 0.76; P < .01). Participants who adhered to both mammography and Pap smear guidelines were significantly more likely to adhere to CRC screening (51.5% CRC screening adherence) compared with women who adhered to neither screening test (8.2% CRC screening adherence), with an adjusted OR of 5.67 (P < .001). Participants who adhered to both mammography and Pap smear guidelines were significantly more likely to adhere to CRC screening than were women who adhered to either screening test (38.0% CRC screening adherence) with an adjusted OR of 1.94 (P < .001). CONCLUSION: Women with up-to-date mammography and cervical cancer screening were more likely to be up-to-date with CRC screening. Regardless of the increased association between non-CRC-related cancer screening and CRC screening, rates of CRC screening utilization remained low in these otherwise compliant populations.     

Flat colorectal lesions in asymptomatic adults: implications for screening with CT virtual colonoscopy

OBJECTIVE: The clinical significance of flat lesions in colorectal cancer screening remains uncertain. The purpose of this study was to investigate the frequency, histology, and virtual colonoscopy detection of flat lesions in an asymptomatic screening population. SUBJECTS AND METHODS: The morphology of all detected polyps was prospectively recorded as flat or polypoid (sessile or pedunculated) in 1,233 consecutive asymptomatic adults who underwent same-day virtual colonoscopy and optical colonoscopy. A flat morphology was defined as a shallow plaquelike broad-based lesion with a height of less than one half of its width. RESULTS: Of 344 polyps of 6 mm or greater confirmed at optical colonoscopy, 17 (4.9%) were labeled as flat at both virtual colonoscopy and optical colonoscopy; 17 (4.9%), at optical colonoscopy only; and 25 (7.3%), at virtual colonoscopy only, yielding 59 total lesions in 52 (4.2%) of 1,233 patients. Twenty-nine (49.2%) of 59 flat lesions were adenomatous, of which four measured 10 mm or greater and one 6- to 9-mm lesion was histologically advanced. None of the 148 diminutive flat lesions (< or = 5 mm) detected at optical colonoscopy was histologically advanced. Virtual colonoscopy prospectively detected 24 (82.8%) of 29 flat adenomas and 47 (80.0%) of all 59 flat lesions 6 mm or greater. In comparison, the sensitivity of virtual colonoscopy for the detection of polypoid adenomas and all polypoid lesions of 6 mm or greater was 86.2% (156/181, p = 0.58) and 81.0% (231/285, p = 0.86), respectively. CONCLUSION: Flat adenomas measuring 6 mm or greater are uncommon in a typical Western screening population, and advanced flat neoplasms are rare. The sensitivity of virtual colonoscopy for detecting flat lesions was similar to that of polypoid lesions. These results indicate that flat lesions are not a significant drawback for virtual colonoscopy screening.     

Using CT Encounters to Improve Colorectal Cancer Screening Utilization: Cross-Sectional Survey Results From the National Health Interview Survey

PurposeMillions of patients undergo CT imaging examinations every year. These encounters may represent opportunities to improve colorectal cancer (CRC) screening rates among patients who have not received recommended CRC screening. Using a nationally representative cross-sectional survey, our purpose was to estimate the proportion of patients who have undergone CT examinations who have not received recommended CRC screening.MethodsSurvey respondents aged 45-75 years in the 2015 National Health Interview Survey without history of CRC were included. Proportion of patients who have undergone CT examinations among those who have not received recommended CRC screening was estimated. Multiple variable logistic regression analyses were performed to evaluate the association between sociodemographic characteristics and CRC screening adherence. Analyses were conducted accounting for complex survey design features.ResultsSixteen thousand two hundred and six survey respondents met inclusion criteria. About 44.3% (43.1, 45.5) reported having ever received a CT scan and 50.8% (49.6, 51.9) underwent CRC screening. Among those who previously had CT scans, Asian race participants and participants without health insurance coverage had lower odds of adherence, while increasing household income and education were associated with higher odds of adherence (P < 0.01). Among participants who did not receive CRC screening, 33.7% (32.1%, 35.3%) reported having a CT scan, representing an estimated 15,278,667 people across the United States.ConclusionAmong patients who have not received recommended CRC screening, nearly 1 out of 3 report having undergone a CT examination. CT encounters may represent opportunities to improve overall CRC screening rates.     

MR colonography without bowel cleansing or water enema: a pilot study

Objectives

The value of screening for colorectal cancer has been well demonstrated, and national programmes are being implemented. At present the primary imaging modality is colonoscopy, which has an associated morbidity and mortality. CT colonography (CTC) has been proposed as an alternative, but this is associated with radiation exposure and generally requires bowel preparation. The aim of this pilot study was to assess the feasibility of MR colonography (MRC) without bowel preparation or water enema for the detection of colorectal neoplasia.

Methods

Patients scheduled for colonoscopy were invited to participate in the study; informed consent was obtained. MRC (with oral barium faecal tagging and colonic air distension) was performed 1–2 weeks before the colonoscopy. Axial T₂ weighted single-shot fast spin-echo (prone and supine) and axial T₁ weighted fast spoiled gradient-recalled (pre- and post-iv gadolinium) supine MRI sequences were performed. The examinations were reported by two gastrointestinal radiologists by consensus. Colonoscopy following standard bowel preparation was performed by a single endoscopist blinded to the MRC results. Significant lesions were defined as polyps or masses >10 mm in diameter.

Results

29 patients were studied. Colonoscopy revealed 25 mass lesions in 13 patients. MRC correctly identified four of the nine lesions >10 mm in diameter (sensitivity 44%; specificity 100%). Although specificity remained high for smaller lesions, sensitivity was poor.

Conclusion

This pilot study has demonstrated the feasibility of performing MRC without bowel preparation or water enema. This would seem to be a promising modality for colorectal cancer screening. Larger studies are required to determine the accuracy of this modality for the detection of colorectal neoplasia.Colorectal cancer (CRC) develops from pre-existing adenomatous polyps. Screening for CRC has been shown to reduce cancer-related mortality by detection of colorectal carcinoma at an earlier stage and by removal of polyps prior to malignant transformation [1]. The mainstay of CRC screening is colonoscopy; however, this is associated with a low morbidity and mortality [2], which assumes greater significance in the context of a screening programme. Discomfort is associated with the procedure itself, but also with the bowel cleansing that is required.There has been considerable interest in the development of non-invasive diagnostic imaging procedures that could offer a more acceptable alternative to colonoscopy. CT colonography (CTC) demonstrates good sensitivity and specificity for polyps ≥10 mm in diameter. However, there is a drop-off in lesion detection at <10 mm, and even more so at <5 mm [3]. Furthermore, radiation exposure may be a concern in a screening programme and, as for colonoscopy, bowel preparation is necessary.MR colonography (MRC), first developed in 1998 [4], offers the advantage over CTC of not involving radiation exposure. The technique for performing MRC has been refined with the development of fast breath-hold sequences with adequate anatomic coverage. Both “bright lumen” (using a gadolinium-spiked water enema) and “dark lumen” (water or gas enema) techniques have been developed [5]. MRC has been shown to have a high sensitivity and specificity for colonic lesions measuring >10 mm [6], and even lesions >5 mm but <10 mm [7,8], when compared with colonoscopy. As with colonoscopy and CTC, however, these techniques required full bowel cleansing.In an attempt to further reduce the discomfort and increase the acceptability of the procedure, Lauenstein et al [9] developed a faecal tagging technique that avoided bowel cleansing. The signal of the intraluminal faecal material was nulled by coating it with a high-concentration barium mixture taken orally over 36 h prior to the procedure. This MRC technique has demonstrated a high sensitivity and specificity for colonic lesions >5 mm in diameter [10].Another attempt at decreasing any discomfort associated with MRC has focused on using room air instead of water for bowel distension [11]. Leung et al [12] have evaluated this technique in a large study and demonstrated a high specificity, although sensitivity was poor for lesions <10 mm.The aim of this pilot study was to assess the feasibility and acceptability of performing MRC without bowel cleansing and using air insufflation instead of water enema for the detection of colorectal neoplasia.     

Screening des kolorektalen Karzinoms

In Germany approximately 29,000 people died of colorectal carcinoma (CRC) in 2002; the risk of getting CRC is 4-6% in Germany, rising with age from the 50th year of life. About one third of all people over 50 years of age have polyps with the potential for malignant transformation in the colorectum, which is a sufficiently high prevalence rate to justify screening. In contrast to most other cancer diseases, in the case of CRC it is possible to prevent the cancer and not only to detect it at an early stage. Application of the test for occult blood in persons between their 45th and 80th years can reduce the mortality of CRC by 14%. We can assume that already regular sigmoidoscopies with consistent performance of polypectomy when needed could reduce the incidence of CRC by 50-70%. There is no doubt that coloscopy is the technique of choice for secondary prevention, as it unites the possibility of complete diagnosis and treatment with a justifiably low level of risk. The economic advantages of an avoidance strategy compared with the treatment of CRC, which is certainly expensive, have been documented. On the basis of all the data reported, in the case of CRC preventive strategies can be emphatically recommended.