602 Fecal Immunochemical Test Is More Cost-Effective Than Guaiac Fecal Occult Blood Test. Comparison Between Two Colorectal Cancer Screening Programs

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Fecal occult blood tests (FOBT) followed by colonoscopy in positive cases is the preferred colorectal cancer (CRC) screening strategy in the most of European countries. Recent reports have shown the superiority of immunological FOBT over the classical guaiac based test. Our objective is to compare two CRC screening programs based on immunological and guaiac FOBT. METHODS: Results from two Spanish regional screening programs have been compared. The Region of Murcia CRC screening program included 35,741 people invited, using a postal based model of invitation, for the realization of an immunological FOBT (FOB-GOLD®), 2 samples with a cut-off of 100 ng/mL. The Valencian Country CRC screening program invited a population of 98,569 people, with a similar postal invitation schedule, using a guaiac based FOBT (Hemoccult®), with 2 samples from 3 consecutive bowel movements. Both Spanish regions are neighbour and with a very similar population structure. RESULTS: Immunological based program had a higher adherence rate (42.3% vs. 35.6%;p=0.00001), a higher positivity rate (9.5% vs. 1.6%; p=0.00001), a better detection rate for high-risk adenoma or cancer (34.17‰ vs. 5.35‰; p>0.00001), and a similar positive predictive value for high-risk adenoma or cancer (PPV) (35.8% vs. 35.9; p<0.05). There were no significant differences in colonoscopy quality indicators (Cecal intubation rate 92.0% vs. 88.1; p<0.05). The cost of the immunological FOBT based program was higher, with an incremental cost of 310€ per screened person. However, estimations of incremental effectivity are better for the immunological FOBT program, with a gain of 12 high-risk adenomas or CRC more detected per 1.000 participants. Cost-effectivity was clearly better with the immunological FOBT based program (3,282€/high-risk adenoma or cancer detected vs. 4,130€/high-risk adenoma or cancer detected) CONCLUSION: Using a similar invitation strategy in very close populations, adherence, positivity rate and detection rate are significantly better for the immunological FOBT, with a similar PPV. Despite a higher cost per screened person, the cost-effectivity of the immunological FOBT based program is also clearly better.

Are Hyperplastic Polyps Precursors of Colorectal Cancer? A Long-Term, Retrospective Study Marielle Bouwens, Eveline Rondagh, Bjorn Winkens, Ann Driessen, Adriaan P. de Bruine, Ad Masclee, Silvia Sanduleanu Traditionally, hyperplastic polyps of the colon were considered to be innocent lesions, with no malignant potential. However, the recently discovered alternative serrated pathway to colorectal cancer (CRC) suggests that at least some of these polyps are potential precursors for CRC. The aims of this study were i) to investigate the relation between hyperplastic polyps and the development of CRC and ii) to analyze the predictors for colorectal cancer in patients with hyperplastic polyps. Patients were retrospectively selected using a national pathology database (PALGA). Between 1991-1998, 943 hyperplastic polyps were detected in 568 patients undergoing diagnostic colonoscopy at our university hospital. Endoscopical data regarding number, size and location of the polyps at the index-colonoscopy were recorded. Endpoints were CRC, last colonoscopy or death. Outcome data were available using the registration database of the Regional Comprehensive Cancer Center. Kaplan-Meyer analysis was used to calculate the risk of CRC in patients with hyperplastic polyps. Results: A total of 568 patients were included (mean (SEM) age: 60 (+/- 1) years, 57% males), 410 patients with hyperplastic polyps only and 158 patients with hyperplastic polyps and also adenomas. Prevalence of CRC was 3.5% during a median follow-up period of 11 years (20 CRC cases), in line with prevalence of CRC in the general Dutch population. CRCs tended to be more frequently located in the right colon compared to the left colon (2.5% versus 1.1%, p=0.074). Multivariate analysis showed that presence of multiple hyperplastic polyps (hazard ratio 2.7, 95% CI 1.1 - 6.9; p=0.043), as well as presence of large (> 5 mm) hyperplastic polyps in the right colon (hazard ratio 7.8, 95% CI 3.0 - 20.5 p < 0.0001) were independent risk factors for the development of CRC. The concomitant presence of adenomas was not an additional risk factor for the development of CRC. Conclusion: Patients with large, right-sided hyperplastic polyps have nearly 8-fold increased risk for development of colorectal cancer. These data reinforce the potential role of the serrated pathway in the pathogenesis of CRC. As surveillance of patients with high-risk hyperplastic polyps remains controversial, development of guidelines is indicated.

603 Comparison of the Yield of Flexible Sigmoidoscopy (FSG) At 3 vs. 5 Years After a Negative Exam Robert E. Schoen, Joel Weissfeld, Adeyinka O. Laiyemo, Vincent P. Doria-Rose, Robert S. Bresalier, Timothy R. Church, Lance Yokochi, Barbara O'Brien, Paul Pinsky Background: To reduce costs, lengthening the time between endoscopic exams has been encouraged. However, there are little data on the impact of delaying the timing of repeat examinations. In the PLCO cancer screening trial, FSG was performed initially at baseline and after 3 years (T3), but in 1998 the protocol was changed and the second exam was performed after 5 years (T5). Aim: To compare the yield of adenoma, advanced adenoma (AA), and cancer in subjects whose initial FSG exam was negative, and whose repeat exam was performed at 3 as opposed to 5 years later. Methods: Participants were enrolled in 10 U.S. centers. Screen-detected abnormalities were referred for diagnostic evaluation and subsequent colonoscopy and pathology results were reviewed. Results: 9,328 subjects (61.6% male, 86.8% white, mean 68.9 years at repeat) returned for an exam 3 years and 23,931 (50.1% male, 89.4% white, mean 66.2 years at repeat) returned for an exam 5 years after a negative FSG. A positive FSG exam for polyp was seen in 11.1 and 15.6% of women and men respectively at T3, and in 17.5 and 23.9% of women and men respectively at T5. The crude number of cancers at T3 was 9 (4 in women, 5 in men, 7 were distal), and at T5 was 24 (15 in men, 9 in women, 15 distal). The total and distal cancer/AA, and cancer/ adenoma yields (per 1000 subjects) are shown (table). Logistic regression adjusting for age, gender, and a colon procedure ≤3 years prior to enrollment showed a higher yield for cancer/adenoma at T5 vs. T3 (OR 1.69; 95%CI 1.49 - 1.92) and for cancer/AA (OR 1.47; 95%CI 1.17 - 1.84). Conclusions: Having a repeat FSG exam at 5 as opposed to 3 years later results in an increased yield of neoplasia, especially in men. Further study of the risk of delaying repeat endoscopic examinations after a negative exam is needed. Age Adjusted Yields

601 Advanced Neoplasia of the Left Hemicolon Are Better Detected By Fit Than Right Sided Lesions Frank A. Oort, René W. van der Hulst, Jochim S. Terhaar sive Droste, Henk van Heukelem, Ruud J. Loffeld, Eric C. Wesdorp, Ruud Duijkers, Rosalie Ooteman, Zaldy D. Valdehueza, Madelon Q. Wentink, Veerle M. Coupe, Gerrit A. Meijer, Chris J. Mulder Introduction: Fecal Immunochemical Tests(FITs)have been proposed as a screening tool for Colorectal Cancer(CRC). FITs detect the globin part of human haemoglobin using specific antibodies. Globin is degraded by digestive enzymes present in the intestinal lumen. Theoretically, this makes FIT selective for occult blood loss in the colon since globin from blood lost proximal to the colon will be degraded. On the other hand, this could have a negative effect on the detection rate of right sided colonic lesions as well. Since the incidence of right sided adenomas and cancers is rising, this could be a pitfall of the use of FIT in CRC screening. Aim: To assess whether there is a difference in sensitivity of FIT for right and left sided advanced neoplasia. Methods: All adult patients scheduled for a colonoscopy in 5 participating hospitals were asked to perform a FIT(OC sensor®, Eiken chemical Co, Japan) on one bowel movement the day prior to colonoscopy. The desktop analyser “OCSENSOR μ” was used for analysis. The cut off value was set at 100ng/ml according to the manufacturers instructions. Test results were compared with colonoscopy outcome as gold standard. Advanced neoplasia are all cancers and advanced adenomas (i.e. ≥1 cm in diameter and/or villous architecture and/or high-grade dysplasia). The right colon was defined as the caecum, ascending and transverse colon including the splenic flexure. The left colon includes the descending colon, sigmoid and rectum. The location of all lesions was assessed by the endoscopist. The chi-square test was used to determine statistical significance. Results: In 1808 individuals who underwent total colonoscopy, 193 advanced adenomas and 62 cancers were found. Individuals with multiple lesions on both sides of the colon were excluded from this analysis(N=48). In the right colon 41 advanced adenomas were found as well as 23 cancers. In the left hemicolon 104 advanced adenomas and 23 cancers were found. The OC-sensor at cut off 100 ng/ml was positive in 11.7% of 1808 individuals. Detection rate for right sided advanced neoplasia was 39.1% versus 56.6% for left sided advanced neoplasia, (P=0.01) (Table 1). Conclusions: Left sided colonic advanced neoplasia are better detected by FIT than right sided lesions. This is an important limitation of FIT when applied in CRC screening, while the incidence of right sided lesions is increasing. Table 1 - FIT detection rates for lesions of the left and right side of the colon

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AGA Abstracts

AGA Abstracts

Fecal Immunochemical Test Is More Cost-Effective Than Guaiac Fecal Occult Blood Test. Comparison Between Two Colorectal Cancer Screening Programs Rodrigo Jover, Fernando Carballo, Teresa Sala, Pedro Zapater, Emilio Torrella, Marta Ponce, Francisco Perez-Riquelme, Jose Cruzado, Dolores Salas