Colorectal Cancer Screening Techniques Research Articles

N32 Implementation of chromoendoscopy in colorectal cancer screening in patients with Inflammatory Bowel Disease

Abstract Background Patients with inflammatory bowel disease (IBD) have a higher risk of colorectal cancer (CRC), so we must implement the best available endoscopic technique to detect it early, decreasing the risk of CRC and death. There is low adherence to CRC screening by chromoendoscopy with dye in patients with IBD, despite the fact that national and international clinical practice guidelines consider this technique of choice based on the available evidence. Description Of The Initiative The standardization of a screening procedure, based on the evidence of endoscopy, allows any member of the team, doctor or nurse, to detect the need for the indication, improving screening in terms of follow-up interval and technique. Likewise, the inflammatory nurse will have to know the technique to be able to inform the patient and improve their adherence, preparation and resolve doubts. The main aim is early detection of dysplasia and CRC. The side aims are: ▪ To improve the implementation of chromoendoscopy as a technique for CRC screening. ▪ Improve patient adherence to colonoscopy. Methods The development of an endoscopic follow-up procedure according to risk factors in patients with ulcerative colitis and colonic Crohn's disease, in which chromoendoscopy is the technique of choice. The technique in our center is with 0.4% carmine indigo diffusion with catheter-diffuser, but it is possible to adapt other alternatives according to availability. The procedure establishes the follow-up interval at 1, 3 or 5 years depending on the low, medium or high risk, respectively, depending on the activity, extent and duration of the disease, presence of stenosis and pseudopolyps, primary sclerosing cholangitis and/or family history of CRC. Results In our center, 100% of screenings are performed by chromoendoscopy with dye, by a single expert endoscopist, scheduled with a longer examination time than a conventional colonoscopy and with optimization of bowel preparation. Conclusion CRC screening of patients with IBD should preferably be performed with chromoendoscopy with dye, establishing follow-up intervals depending on known risk factors, both clinical, endoscopic and histological, and this indication should be standardized in a procedure that is known to all members of the team.

Noninvasive colorectal cancer screening techniques: literature review

Fecal DNA testing is a noninvasive method recommended by professional medical societies for colorectal cancer screening in individuals with intermediate risk of the disease. Adenamatous and serrated lesions, as well as cancer, lead to exfoliation of cells containing neoplastic altered DNA which, in turn, can be detected with sensitive testing methods aimed at specific genetic and epigenetic biomarkers. Mt-sDNA test approved by the United States Food and Drug Administration in 2014 showed sensitivity of 92 % for detection of colorectal cancer which is much higher than sensitivity of fecal immunochemical test (74 %).

The Public Perception of CT Colonography Versus Colonoscopy via Sentiment Analysis of Social Media

PurposeThe purpose of this study was to understand the public perception of CT colonography (CTC) in comparison with optical colonoscopy as a colorectal cancer screening technique. MethodsIn this observational study, all English-language tweets from January 1, 2015, until September 1, 2021, containing terms related to CTC and terms related to optical colonoscopy were collected. The tweets were given sentiment scores using Twitter-roBERTa-base, a natural language processing model. These scores were then used to classify tweets into positive, neutral, and negative categories. The numbers of negative, positive, and neutral tweets were tabulated. ResultsA total of 4,709 tweets from 2,194 users relating to CTC were collected. Of these tweets, 9.81% were negative, 68.52% were neutral, and 21.63% were positive. In comparison, a total of 445,969 tweets from 261,209 users were collected relating to optical colonoscopy. Of these tweets, 31.8% were negative, 51.3% were neutral, and 16.9% were positive. ConclusionsThe public awareness of CTC remains limited in comparison with optical colonoscopy, with Twitter volume relating to CTC being about 1% the volume for optical colonoscopy. There was a higher proportion of negative tweets regarding colonoscopy. The lower proportion of negative tweets regarding CTC may be helpful in encouraging its use as an alternative to optical colonoscopy, with the aim of increasing uptake of colorectal cancer screening.

Incidence, mortality, survival, risk factor and screening of colorectal cancer: A comparison among China, Europe, and northern America.

Colorectal cancer (CRC) is one of the most common malignancies worldwide. China, Europe and northern America account for more than half of the new CRC cases and associated deaths globally. This review summarizes the current status and temporal trends of CRC in China, Europe, and northern America. The potential primary preventive strategies and latest advances in CRC screening techniques and programs are discussed. Recently, the incidence and mortality of CRC in some European and northern American countries have decreased; conversely, CRC incidence and mortality continue to increase in China. The overall 5-year relative survival rate for CRC is similar between these regions, but there is considerable heterogeneity among European countries. Implementing population-based CRC screening programs can effectively address the growing disease burden. The effectiveness of nationwide CRC screening programs in these regions has been limited by relatively low coverage and participation rate. The deployment of state-of-the-art techniques and precise risk-adapted screening strategies incorporating effective risk prediction models and screening techniques may boost screening effectiveness. Our review provides novel foundations for the development and optimization of CRC preventive strategies.

Towards Novel Non-Invasive Colorectal Cancer Screening Methods: A Comprehensive Review.

Simple SummarySince the 70s, a variety of colorectal cancer (CRC) screening programs have been adopted throughout the world with the aim of reducing the mortality rate of one of the leading cancer-related causes of death in the world. However, currently employed techniques present numerous shortcomings that negatively affect early-stage CRC detection, thus urging us to consider new and improved alternatives. Among the cited shortcomings are invasiveness and cultural stigma surrounding certain sample collection techniques, both of which negatively affect screening compliance. For this reason, many of the viable alternatives collected and described in this review aim to achieve good diagnostic performance while minimizing patient stress and discomfort. This text should serve as a guiding light for healthcare providers specialized in preventive medicine in the continuous pursuit of improved patient care.Colorectal cancer (CRC) is one of the leading cancer-related causes of death in the world. Since the 70s, many countries have adopted different CRC screening programs, which has resulted in a decrease in mortality. However, current screening test options still present downsides. The commercialized stool-based tests present high false-positive rates and low sensitivity, which negatively affects the detection of early stage carcinogenesis. The gold standard colonoscopy has low uptake due to its invasiveness and the perception of discomfort and embarrassment that the procedure may bring. In this review, we collected and described the latest data about alternative CRC screening techniques that can overcome these disadvantages. Web of Science and PubMed were employed as search engines for studies reporting on CRC screening tests and future perspectives. The searches generated 555 articles, of which 93 titles were selected. Finally, a total of 50 studies, describing 14 different CRC alternative tests, were included. Among the investigated techniques, the main feature that could have an impact on CRC screening perception and uptake was the ease of sample collection. Urine, exhaled breath, and blood-based tests promise to achieve good diagnostic performance (sensitivity of 63–100%, 90–95%, and 47–97%, respectively) while minimizing stress and discomfort for the patient.

Cost-Effectiveness Analysis of Colorectal Cancer Screening: A Systematic Review.

IntroductionColorectal cancer (CRC) is a significant health problem with an increasing incidence worldwide. Screening is one of the ways, in which cases and deaths of CRC can be prevented. The objective of this systematic review was to evaluate the cost-effectiveness of the different CRC screening techniques and to specify the efficient technique from a cost-effectiveness perspective.MethodsThe economic studies of CRC screening in general populations (average risk), aged 50 years and above were reviewed. Two reviewers independently reviewed the titles, abstracts, and full-texts of the studies in five databases: Cochrane, Embase, Scopus, Web of Science and PubMed. The disagreements between reviewers were resolved through the authors’ consensus. The main outcome measures in this systematic review were the incremental cost-effectiveness ratio (ICER) of screening versus no-screening and then in comparison with other screening techniques. The ICER is defined by the difference in cost between two possible interventions, divided by the difference in their effect.ResultsEight studies were identified and retained for the final analysis. In this study, when screening techniques were compared to no-screening, all CRC screening techniques showed to be cost-effective. The lowest ICER calculated was $PPP −16265/quality-adjusted life-year (QALY) (the negative ICERs were between purchasing power parity in US dollar ($PPP) −16265/QALY to $PPP −1988/QALY, whereas the positive ICERs were between $PPP 1257/QALY to $PPP 55987/QALY). For studies comparing various screening techniques, there was great heterogeneity in terms of the structures of the analyses, leading to diverse conclusions about their incremental cost-effectiveness.ConclusionAll CRC screening techniques were cost-effective, compared with the no-screening methods. The cost-effectiveness of the various screening techniques mainly was dependent on the context-specific parameters and highly affected by the framework of the cost-effectiveness analysis. In order to make the studies comparable, it is important to adopt a reference-based methodology for economic evaluation studies.

Colorectal Cancer in Brunei Darussalam: An Overview and Rationale for National Screening Programme.

Colorectal cancer (CRC) is the third most common cancer worldwide after lung and breast cancers, and ranks second in terms of cancer mortality globally. Brunei Darussalam reports high incidence of CRC in the Southeast Asian region and has no formal national screening programme for CRC. Screening for CRC in Brunei Darussalam is offered in an opportunistic fashion for individuals with average or above average risks for CRC, that is, the individual has a positive family history of CRC or neoplasms and is more than 50 years old. Opportunistic screening is widely practiced but this is not standardised. The Ministry of Health in Brunei Darussalam is currently in the process of implementing a CRC screening programme as part of a larger national health screening based on the increasing incidence of non-communicable diseases (NCDs). This review article assesses the situation of CRC in Brunei Darussalam from the 1980s to present day, including incidence of CRC in different age groups, ethnicities and genders; relevant non-modifiable and modifiable risk factors of CRC in Brunei Darussalam setting; and common CRC screening techniques used in Brunei Darussalam as well as other Asia-Pacific countries. The review also discusses the merits of a national CRC screening programme. With the increasing incidence of CRC worldwide and in Brunei Darussalam, national screening for CRC in Brunei Darussalam is an important strategy to lower morbidity and mortality rates. A review of the progress and outcome of the national screening programme will be available a few years after rollout.

Addressing priority challenges in the detection and assessment of colorectal polyps from capsule endoscopy and colonoscopy in colorectal cancer screening using machine learning

Background: Colorectal capsule endoscopy (CCE) is a potentially valuable patient-friendly technique for colorectal cancer screening in large populations. Before it can be widely applied, significant research priorities need to be addressed. We present two innovative data science algorithms which can considerably improve acquisition and analysis of relevant data on colorectal polyps obtained from capsule endoscopy.Material and methods: A fully paired study was performed (2015–2016), where 255 participants from the Danish national screening program had CCE, colonoscopy, and histopathology of all detected polyps. We developed: (1) a new algorithm to match CCE and colonoscopy polyps, based on objective measures of similarity between polyps, and (2) a deep convolutional neural network (CNN) for autonomous detection and localization of colorectal polyps in colon capsule endoscopy.Results and conclusion: Unlike previous matching methods, our matching algorithm is able to objectively quantify the similarity between CCE and colonoscopy polyps based on their size, morphology and location, and provides a one-to-one unequivocal match between CCE and colonoscopy polyps. Compared to previous methods, the autonomous detection algorithm showed unprecedented high accuracy (96.4%), sensitivity (97.1%) and specificity (93.3%), calculated in respect to the number of polyps detected by trained nurses and gastroenterologists after visualizing frame-by-frame the CCE videos.

Colon cancer screening with CT colonography: logistics, cost-effectiveness, efficiency and progress.

Colorectal cancer (CRC) incidence and mortality can be significantly reduced by population screening. Several different screening methods are currently in use, and this review focuses specifically on the imaging technique computed tomographic colonography (CTC). The challenges and logistics of CTC screening, as well as the importance of test accuracy, uptake, quality assurance and cost-effectiveness will be discussed. With comparable advanced adenoma detection rates to colonoscopy (the most commonly used whole-colon investigation), CTC is a less-invasive alternative, requiring less laxative, and with the potential benefit that it permits assessment of extracolonic structures. Three large-scale European trials have contributed valuable evidence supporting the use of CTC in population screening, and highlight the importance of selecting appropriate clinical management pathways based on initial CTC findings. Future research into CTC-screening will likely focus on radiologist training and CTC quality assurance, with identification of evidence-based key performance indicators that are associated with clinically-relevant outcomes such as the incidence of post-test interval cancers (CRC occurring after a presumed negative CTC). In comparison to other CRC screening techniques, CTC offers a safe and accurate option that is particularly useful when colonoscopy is contraindicated. Forthcoming cost-effectiveness analyses which evaluate referral thresholds, the impact of extra-colonic findings and real-world uptake will provide useful information regarding the feasibility of future CTC population screening.

Cell-surface markers for colon adenoma and adenocarcinoma.

Early detection of colorectal cancer (CRC) is crucial for effective treatment. Among CRC screening techniques, optical colonoscopy is widely considered the gold standard. However, it is a costly and invasive procedure with a low rate of compliance. Our long-term goal is to develop molecular imaging agents for the non-invasive detection of CRC by molecular imaging-based colonoscopy using CT, MRI or fluorescence. To achieve this, cell surface targets must be identified and validated. Here, we report the discovery of cell-surface markers that distinguish CRC from surrounding tissues that could be used as molecular imaging targets. Profiling of mRNA expression microarray data from patient tissues including adenoma, adenocarcinoma, and normal gastrointestinal tissues was used to identify potential CRC specific cell-surface markers. Of the identified markers, six were selected for further validation (CLDN1, GPR56, GRM8, LY6G6D/F, SLCO1B3 and TLR4). Protein expression was confirmed by immunohistochemistry of patient tissues. Except for SLCO1B3, diffuse and low expression was observed for each marker in normal colon tissues. The three markers with the greatest protein overexpression were CLDN1, LY6G6D/F and TLR4, where at least one of these markers was overexpressed in 97% of the CRC samples. GPR56, LY6G6D/F and SLCO1B3 protein expression was significantly correlated with the proximal tumor location and with expression of mismatch repair genes. Marker expression was further validated in CRC cell lines. Hence, three cell-surface markers were discovered that distinguish CRC from surrounding normal tissues. These markers can be used to develop imaging or therapeutic agents targeted to the luminal surface of CRC.

Preferences for Colorectal Cancer Screening Techniques and Intention to Attend: a Multi-Criteria Decision Analysis

Despite the expected health benefits of colorectal cancer screening programs, participation rates remain low in countries that have implemented such a screening program. The perceived benefits and risks of the colorectal cancer screening technique are likely to influence the decision to attend the screening program. Besides the diagnostic accuracy and the risks of the screening technique, which can affect the health of the participants, additional factors, such as the burden of the test, may impact the individuals' decisions to participate. To maximise the participation rate of a screening program for a new colorectal cancer program in the Netherlands, it is important to know the preferences of the screening population for alternative screening techniques. The aim of this study was to explore the impact of preferences for particular attributes of the screening tests on the intention to attend a colorectal cancer screening program. We used a web-based questionnaire to elicit the preferences of the target population for a selection of colon-screening techniques. The target population consisted of Dutch men and women aged 55-75 years. The analytic hierarchy process (AHP), a technique for multi-criteria analysis, was used to estimate the colorectal cancer screening preferences. Respondents weighted the relevance of five criteria, i.e. the attributes of the screening techniques: sensitivity, specificity, safety, inconvenience, and frequency of the test. With regard to these criteria, preferences were estimated between four alternative screening techniques, namely, immunochemical fecal occult blood test (iFOBT), colonoscopy, sigmoidoscopy, and computerized tomographic (CT) colonography. A five-point ordinal scale was used to estimate the respondents' intention to attend the screening. We conducted a correlation analysis on the preferences for the screening techniques and the intention to attend. We included 167 respondents who were consistent in their judgments of the relevance of the criteria and their preferences for the screening techniques. The most preferred screening method for the national screening program was CT colonography. Sensitivity (weight = 0.26) and safety (weight = 0.26) were the strongest determinants of the overall preferences for the screening techniques. However, the screening test with the highest intention to attend was iFOBT. Inconvenience (correlation [r] = 0.69), safety (r = 0.58), and the frequency of the test (r = 0.58) were most strongly related to intention to attend. The multi-criteria decision analysis revealed the attributes of the screening techniques that are most important so as to increase intention to participate in a screening program. Even though the respondents may recognize the high importance of diagnostic effectiveness in the long term, their short-term decision to attend the screening tests may be less driven by this consideration. Our analysis suggests that inconvenience, safety, and frequency of the test are the strongest technique-related determinants of the respondents' intention to participate in colorectal screening programs.

Time requirements and health effects of participation in colorectal cancer screening with colonoscopy or computed tomography colonography in a randomized controlled trial

Time limitations and unwanted health effects may act as barriers to participation in colorectal cancer (CRC) screening. The aim of the study was to measure the time requirements and health effects of colonoscopy and computed tomography colonography (CTC) screening. This was a prospective diary study in a consecutive sample within a randomized controlled CRC screening trial, comparing primary colonoscopy and CTC screening for average-risk individuals aged 50 - 74 years. The diary ended when all screening-related complaints had passed. The diary was returned by 75 % (241/322) of colonoscopy and 75 % (127/170) of CTC screenees. The median interval between leaving home and returning from the examination was longer for colonoscopy (4 hours and 18 minutes [4:18], interquartile range [IQR] 3:30 - 5:00) than for CTC (2:30 hours, IQR 2:06 - 3:00; P < 0.001). Similarly, the time to return to routine activities was longer after colonoscopy (3:54 hours, IQR 1:48 - 15:00) than after CTC (1:36 hours, IQR 0:54 - 4:42). The duration of screening-related symptoms after the examination was shorter for colonoscopy (11:00 hours, IQR 2:54 - 20:00) than for CTC (22:00 hours; IQR 5:30 - 47:00; P < 0.001). Abdominal complaints were reported more frequently after CTC. Anxiety, pain, and quality of life worsened during the screening process, with no differences between the two examinations. Compared with colonoscopy, CTC screening required less time and allowed screenees to return to their daily activities more quickly. In contrast, CTC was associated with a twofold longer duration of screening-related symptoms. Feelings of anxiety, pain, and quality of life scores were similar during colonoscopy and CTC screening. These results should be incorporated into cost-effectiveness analyses of CRC screening techniques.

Use of RNA isolated from feces as a promising tool for the early detection of colorectal cancer

Colorectal cancer is one of the most common forms of cancer worldwide. Early detection would allow patients to be treated surgically and halt the progression of the disease; however, the current methods of early detection are invasive (colonoscopy and sigmoidoscopy) or have low sensitivity (fecal occult blood test). The altered expression of genes in stool samples of patients with colorectal cancer can be determined by RT-PCR. This is a noninvasive and highly sensitive technique for colorectal cancer screening. According to information gathered in this review and our own experience, the use of fecal RNA to determine early alterations in gene expression due to malignancy appears to be a promising alternative to the current detection methods and owing to its low cost could be implemented in public health services.

Mo1558 The Efficacy of CT Colonography in the Detection of Colonic Lesions (Flat and Polypoid) Compared to Optical Colonoscopy: A Meta-Analysis

Colorectal cancer (CRC) is the second leading cause of cancer death in the United States with approximately 150,000 new cases every year. Flat adenomas are known to have an increased risk of harboring high-grade dysplasia which may progress to invasive adenocarcinoma. Computed tomographic colonography (CTC), is an evolving technique for CRC screening and its use has been a heated topic of debate in the medical community. The reported efficacy of CTC has shown variable results especially in the detection of flat polyps.

Colonic polyps: inheritance, susceptibility, risk evaluation, and diagnostic management.

Colorectal cancer (CRC) is the third-ranked neoplasm in order of incidence and mortality, worldwide, and the second cause of cancer death in industrialized countries. One of the most important environmental risk factors for CRC is a Western-type diet, which is characterized by a low-fiber and high-fat content. Up to 25% of patients with CRC have a family history for CRC, and a fraction of these patients are affected by hereditary syndromes, such as familial adenomatous polyposis, Gardner or Turcot syndromes, or hereditary nonpolyposis colorectal cancer. The onset of CRC is triggered by a well-defined combination of genetic alterations, which form the bases of the adenoma-carcinoma sequence hypothesis and justify the set-up of CRC screening techniques. Several screening and diagnostic tests for CRC are illustrated, including rectosigmoidoscopy, optical colonoscopy (OC), double contrast barium enema (DCBE), and computed tomography colonography (CTC). The strengths and weaknesses of each technique are discussed. Particular attention is paid to CTC, which has evolved from an experimental technique to an accurate and mature diagnostic approach, and gained wide acceptance and clinical validation for CRC screening. This success of CTC is due mainly to its ability to provide cross-sectional analytical images of the entire colon and secondarily detect extracolonic findings, with minimal invasiveness and lower cost than OC, and with greater detail and diagnostic accuracy than DCBE. Moreover, especially with the advent and widespread availability of modern multidetector CT scanners, excellent quality 2D and 3D reconstructions of the large bowel can be obtained routinely with a relatively low radiation dose. Computer-aided detection systems have also been developed to assist radiologists in reading CTC examinations, improving overall diagnostic accuracy and potentially speeding up the clinical workflow of CTC image interpretation.

Colonic polyps: inheritance, susceptibility, risk evaluation, and diagnostic management

Colonic polyps: inheritance, susceptibility, risk evaluation, and diagnostic management Emanuele Neri, Lorenzo Faggioni, Lorenzo Cini, Carlo BartolozziDiagnostic and Interventional Radiology, University of Pisa, Pisa, ItalyAbstract: Colorectal cancer (CRC) is the third-ranked neoplasm in order of incidence and mortality, worldwide, and the second cause of cancer death in industrialized countries. One of the most important environmental risk factors for CRC is a Western-type diet, which is characterized by a low-fiber and high-fat content. Up to 25% of patients with CRC have a family history for CRC, and a fraction of these patients are affected by hereditary syndromes, such as familial adenomatous polyposis, Gardner or Turcot syndromes, or hereditary nonpolyposis colorectal cancer. The onset of CRC is triggered by a well-defined combination of genetic alterations, which form the bases of the adenoma-carcinoma sequence hypothesis and justify the set-up of CRC screening techniques. Several screening and diagnostic tests for CRC are illustrated, including rectosigmoidoscopy, optical colonoscopy (OC), double contrast barium enema (DCBE), and computed tomography colonography (CTC). The strengths and weaknesses of each technique are discussed. Particular attention is paid to CTC, which has evolved from an experimental technique to an accurate and mature diagnostic approach, and gained wide acceptance and clinical validation for CRC screening. This success of CTC is due mainly to its ability to provide cross-sectional analytical images of the entire colon and secondarily detect extracolonic findings, with minimal invasiveness and lower cost than OC, and with greater detail and diagnostic accuracy than DCBE. Moreover, especially with the advent and widespread availability of modern multidetector CT scanners, excellent quality 2D and 3D reconstructions of the large bowel can be obtained routinely with a relatively low radiation dose. Computer-aided detection systems have also been developed to assist radiologists in reading CTC examinations, improving overall diagnostic accuracy and potentially speeding up the clinical workflow of CTC image interpretation.Keywords: colonic polyps, colorectal cancer, colonoscopy, double contrast barium enema, computed tomography colonography

ACR Appropriateness Criteria® on Colorectal Cancer Screening

Colorectal cancer remains one of the most common causes of cancer death in this country. This malignancy is ideally suited for screening because the detection and removal of the precursor adenomatous polyp can prevent most colorectal cancers from ever forming. The choice of a test for screening involves consideration of various individual parameters, including patient age and the presence of risk factors for the development of colorectal cancer. Computed tomographic colonography (CTC) has emerged as the leading imaging technique for colorectal cancer screening in average-risk individuals on the basis of the evidence presented in this paper. The double-contrast barium enema is an alternative imaging test that is appropriate particularly when CTC is not available. In 2008, the American Cancer Society guideline for colorectal cancer screening was revised jointly with the US Multi-Society Task Force on Colorectal Cancer and the ACR to include CTC every 5 years as an option for average-risk individuals. Computed tomographic colonography is also the preferred test for colon evaluation after an incomplete colonoscopy. Imaging tests including CTC and the double-contrast barium enema are usually not indicated for colorectal cancer screening in high-risk patients with polyposis syndromes or inflammatory bowel disease. This paper presents the new colorectal cancer imaging test ratings and is the result of evidence-based consensus by the ACR Appropriateness Criteria Expert Panel on Gastrointestinal Imaging.

Optical Measurement of Rectal Microvasculature as an Adjunct to Flexible Sigmoidosocopy: Gender-Specific Implications

Flexible sigmoidoscopy is a robust, clinically validated, and widely available colorectal cancer screening technique that is currently sanctioned by major guideline organizations. Given that endoscopic visualization is generally limited to the distal third of the colon and women tend to have a proclivity for proximal lesions, the flexible sigmoidoscopy performance is markedly inferior in women than in men. Our group has shown that by using a novel light-scattering approach, we were able to detect an early increase in blood supply (EIBS) in the distal colonic mucosa, which served as a marker of field carcinogenesis and, hence, proximal neoplasia. Therefore, we sought to ascertain whether rectal EIBS would improve flexible sigmoidoscopy, especially in women. A polarization-gated spectroscopy fiber-optic probe was used to assess EIBS in the endoscopically normal rectum (n = 366). When compared with gender-matched neoplasia-free controls, females with advanced proximal neoplasia (n = 10) had a robust (60%; P = 0.002) increase in rectal mucosal oxyhemoglobin content whereas the effect size in males was less marked (33%; P = 0.052). In women, addition of rectal oxyhemoglobin tripled the sensitivity for advanced neoplasia over flexible sigmoidoscopy alone. Indeed, the performance characteristics seemed to be excellent (sensitivity, 100%; specificity, 76.8%; positive predictive value, 32.6%; and negative predictive value, 100%). A variety of nonneoplastic factors were assessed and did not confound the relationship between rectal EIBS and advanced neoplasia. Therefore, using rectal EIBS in combination with flexible sigmoidoscopy mitigated the gender gap and may allow flexible sigmoidoscopy to be considered as a viable colorectal cancer screening test in women.

Comparing Three Colorectal Cancer Screening Techniques

A recent randomized trial found that, compared with traditional guaiac-based fecal occult blood testing (FOBT), immunochemical FOBT detected more

Hepatic Steatosis (Fatty Liver Disease) in Asymptomatic Adults Identified by Unenhanced Low-Dose CT

The purpose of this study was to investigate the prevalence of hepatic steatosis in an asymptomatic U.S. adult population using attenuation values at unenhanced CT as the reference standard. We also assessed the utility of known clinical risk factors for diagnosis. For 3,357 consecutive asymptomatic adults (1,865 women and 1,492 men; mean age, 57.0 years), hepatic and splenic CT attenuation values (Hounsfield units) were obtained by unenhanced CT using a low-dose colonography technique for colorectal cancer screening. Multiple attenuation criteria for steatosis were applied, including liver thresholds and comparison of liver and spleen attenuation. Relevant clinical risk factors were compared against a CT liver attenuation < or = 40 HU, which has been shown to exclude mild steatosis. Mean liver attenuation was 58.8 +/- 10.8 (SD) HU. The prevalence of moderate-to-severe hepatic steatosis (defined by liver attenuation < or = 40 HU) was 6.2% (208/3,357). For CT attenuation criteria that include milder degrees of steatosis, prevalence increased to as high as 45.9% (1,542/3,357) for a liver-to-spleen attenuation ratio of < or = 1.1. Overweight status (body mass index > 25) was a sensitive indicator for moderate-to-severe steatosis (92.8%) but was highly nonspecific (37.5%). Other clinical risk factors, such as diabetes, dyslipidemia, hypertension, alcohol overuse, and hepatitis, were more specific (77.6-92.4%) but highly insensitive (1.9-37.5%). Combining clinical risk factors did not substantially increase the accuracy for screening. Assessment of liver attenuation by use of unenhanced CT represents an objective and noninvasive means for detection of asymptomatic hepatic steatosis, whereas clinical risk factor assessment is unreliable. Further longitudinal investigation is needed to determine the most appropriate attenuation threshold and the risk for disease progression to steatohepatitis and cirrhosis.