W1980 Rectal Aberrant Crypt Foci (ACF) Among Subjects with a History of High-Risk Colorectal Neoplasia (CRN).

W1979

AGA Abstracts

Prevalence of Transformed Adenomas Among Colonic Sessile Serrated Adenomas. Results of a Prospective Monocentric Study Ulriikka Chaput, Benoit Terris, Romain Coriat, Marianne Gaudric, Frederic Prat, Stanislas Chaussade Introduction Sessile serrated adenomas (SSA) form a heterogeneous group of lesions. Risk of occurence of high grade dysplasia is unknown. The aim of this study was to evaluate the prevalence of transformed adenomas (defined by the presence of high grade dysplasia, in situ carcinoma or intra mucosa carcinoma) among SSA and to compare them to the other histological types of adenomas. Methods The endoscopic and anatomopathological reports of the colonoscopies realised in our center between may 2006 and september 2008 were collected. For every patient, only the biggest polyp was taken into account. Informations about the polyps and the patients were collected prospectively. All the anatomopathological analysis were performed in our center. Only patients with adenomas were included. Adenomas were distributed in three groups : SSA, exclusively tubular adenomas, villous adenomas. Results The study included 462 adenomas. The characteristics of the patients are represented in table 1. None of the SSA presented high grade dysplasia. The prevalence of transformed adenomas is represented in table 2. To take into account the differences between the groups, SSA were matched with other histological types of adenomas according to the sex and age +/- 5 years of the patient, and to the size of the adenoma +/- 5 mm. Thirty one sessile serrated adenomas were matched with 50 tubular adenomas. The prevalence of transformed adenomas was respectively 0 and 12% (p=0.08). Twenty-three SSA were matched with 31 villous adenomas. The prevalence of transformed adenomas was respectively 0 and 29%(p<0,01). Conclusion No transformed adenoma was diagnosed among SSA. These results suggest that SSA would present a different natural history : they would become rapidly an adenocarcinoma or first become a classical adenoma masking completely their serrated aspect. Table 1 : Characteristics of the patients

Table 2 : Prevalence of transformed adenomas among the different histological types of adenomas

W1981 What Determines Individuals' Preferences for Colorectal Cancer Screening Tests? a Discrete Choice Experiment Lieke Hol, Leonie van Dam, Esther W. de Bekker-Grob, Ewout W Steyerberg, Ernst J. Kuipers, J. D. Habbema, Marie Louise Essink-Bot, Monique van Leerdam INTRODUCTION: Randomized controlled trials provided evidence for the effectiveness of colorectal cancer (CRC) screening. AGA guidelines recommend screening with any test. Uptake of CRC screening remains low despite efforts to increase participation rates. We therefore aimed to determine how procedural characteristics of various CRC screening tests determine preferences for participation, and how individuals weigh these against the perceived benefits from participation in CRC screening. METHODS: We designed a discrete choice experiment (DCE) in which subjects had to choose repetitively between a ‘no screening alternative' and two screening alternatives that differed in seven characteristics: pain, risk of complications, location (at home or in the hospital), preparation, duration of the procedure, screening interval and risk reduction of death from CRC. The questionnaire was sent to 712 individuals aged 50-74 years old including 500 screening naïve individuals and 212 individuals who underwent CRC screening as part of the Dutch randomized trial comparing two fecal occult blood tests (FOBT) and sigmoidoscopy. RESULTS: In total, 155 (31%) of screening naïve subjects (men 50%; mean age 62±6yrs) and 121 (57%) of the participants (men 49%; mean age 60±6yrs) returned the questionnaire. Respectively 96% and 91% of respondents passed the rationality test. All screening attributes proved to be important for the respondents' preferences, except for location, which did not influence preferences of the screening naïve individuals. There were no significant differences in preferences between screening naïve individuals and participants, besides location. For both groups combined, individuals required an additional risk reduction of death from CRC by a screening test of 1% for every additional 10 minutes of duration, 5% in order to expose themselves to a small risk of complications, 9% to accept mild pain, 10% to undergo preparation with an enema, 14% to use 0.75 liters of oral preparation and 12 hours fasting and 33% to use 4 liters of oral preparation and 18 hours fasting. Screening intervals shorter than once every 10 years were significantly preferred to a 10-year screening interval (all p-values <0.01). CONCLUSION: Procedural aspects of CRC screening tests were important determinants of individuals' preferences. The burden of preparation was considered the most important drawback. The finding that subjects preferred the screening interval to be shorter than 10 years suggests that they value the reassurance gained by undergoing screening. Our data can be used to inform potential screenees tailored to their needs, which may further improve uptake of CRC screening.

W1980 Rectal Aberrant Crypt Foci (ACF) Among Subjects with a History of HighRisk Colorectal Neoplasia (CRN). Paul J. Limburg, Michelle R. Mahoney, Stephen J. Sontag, Robert E. Schoen, Richard V. Benya, Michael J. Lawson, David Weinberg, Elena M. Stoffel, Russell I. Heigh, Michael V. Chiorean, Joel Levine, Christopher J. Gostout Background: ACF have been associated with colorectal cancer (CRC) risk in animal and human studies. However, to date, few reports have described ACF prevalence & morphological features among high-risk subjects. Aim: To further characterize ACF among subjects with > 1 cm, > 3 total, or histologically advanced (villous morphology, high-grade dysplasia, invasive cancer) CRN. Methods: Subjects were recruited at 11 sites for an ongoing CRC chemoprevention trial. Endoscopists completed a brief ACF training course, then performed magnification chromoendoscopy using a prototype colonoscope (Olympus CF-Q160ALE). Overall ACF number (ACF-N), crypt number (CN), lumen shape (LS), tissue plane (TP) and relative staining intensity (SI) were recorded; biopsies were not obtained (change in ACF-N defined as the chemoprevention trial endpoint). Fisher's exact, Chi-square, and Kruskal-Wallis tests were used to compare CN, LS, TP, and SI across ACF-N subgroups (04, 5-9, 10+). Results: Among 119/147 (81%) subjects with complete ACF data, the mean (SD) and range for ACF-N were 8.3 (5.5) and 1-34, respectively; 73% had > 5 ACF. LS, TP, and SI differed significantly by ACF-N subgroup, while CN did not (Table). Conclusions: In this multi-center study, most high-risk subjects had > 5 prevalent ACF. Select morphological features were also associated with ACF-N. Further investigation is needed to determine how these characteristics relate to tissue histology and chemopreventive response.

W1982 Barriers to Colorectal Cancer Screening Among Hispanics: A Nation-Wide Population-Based Study Jianmin Tian, Beili Dong Introduction: Colorectal cancer (CRC) is the 2nd leading cause of cancer death, and CRC screening can reduce mortality for individuals aged 50 years and older. However, CRC screening is much lower among Hispanics than non-Hispanics (46% vs. 64 %) according to BRFSS (Behavioral Risk Factor Surveillance System) 2006 national data. Only a few small studies from single geographic regions addressed the factors associated with this disparity. This study is to investigate the risk factors associated with low CRC screening rate among Hispanics. Methods: BRFSS (sponsored by CDC) is the largest telephone survey of adult population in US. In this study we selected all Hispanic respondents in 2006 BRFSS survey

AGA Abstracts

A-766