Nonbleeding adenomas: Evidence of systematic false-negative fecal immunochemical test results and their implications for screening effectiveness-A modeling study.

BACKGROUND: If some adenomas do not bleed over several years, they will cause systematic false-negative fecal immunochemical test (FIT) results. The long-term effectiveness of FIT screening has been estimated without accounting for such systematic false-negativity. There are now data with which to evaluate this issue. METHODS: The authors developed one microsimulation model (MISCAN [MIcrosimulation SCreening ANalysis]-Colon) without systematic false-negative FIT results and one model that allowed a percentage of adenomas to be systematically missed in successive FIT screening rounds. Both variants were adjusted to reproduce the first-round findings of the Dutch CORERO FIT screening trial. The authors then compared simulated detection rates in the second screening round with those observed, and adjusted the simulated percentage of systematically missed adenomas to those data. Finally, the authors calculated the impact of systematic false-negative FIT results on the effectiveness of repeated FIT screening. RESULTS: The model without systematic false-negativity simulated higher detection rates in the second screening round than observed. These observed rates could be reproduced when assuming that FIT systematically missed 26% of advanced and 73% of nonadvanced adenomas. To reduce the false-positive rate in the second round to the observed level, the authors also had to assume that 30% of false-positive findings were systematically false-positive. Systematic false-negative FIT testing limits the long-term reduction of biennial FIT screening in the incidence of colorectal cancer (35.6% vs 40.9%) and its mortality (55.2% vs 59.0%) in participants. CONCLUSIONS: The results of the current study provide convincing evidence based on the combination of real-life and modeling data that a percentage of adenomas are systematically missed by repeat FIT screening. This impairs the efficacy of FIT screening. Cancer 2016;122:1680-8. © 2016 American Cancer Society.

Developing a score chart to improve risk stratification of patients with colorectal adenoma.

BACKGROUND AND STUDY AIMS: Current surveillance guidelines risk stratify patients with adenoma by using only one or two factors: adenoma multiplicity or presence of an advanced adenoma characteristic. Combinations of adenoma characteristics are not considered, which limits the predictive value of these guidelines. The aim of the study was to develop a scoring system for more refined risk stratification of patients with adenoma. PATIENTS AND METHODS: The Dutch Pathology Registry (PALGA) was used to identify newly diagnosed patients with adenoma in 10 Dutch hospitals between 1988 and 2002. Medical records were reviewed until 1 December 2008 for follow-up. Logistic regression analysis was used to assess patient- and adenoma-related predictors of metachronous advanced neoplasia. The prediction model was validated by bootstrapping and cross-validation. A score chart was developed based on identified adenoma-related predictors. The discriminative ability of the prediction model was compared with currently used risk stratifications in surveillance guidelines. RESULTS: A total of 2914 patients with adenoma were included (mean age 61 years; 55 % male). The score chart consisted of characteristics that contributed 1 point (size ≥ 10 mm, villous histology, proximal location, having 2 - 4 adenomas) or 2 points (having ≥ 5 adenomas). A patient's adenoma risk score could range from 0 to 5 points. A score of 5 for a 75-year-old man implied a 5-year risk of advanced neoplasia of 46 %. The discriminative ability of the model was moderate (c-statistic 0.712) but better than risk stratifications in current international guidelines, which had c-statistics of 0.642 - 0.674. CONCLUSION: A score chart that combines adenoma-related predictors of advanced colorectal neoplasia optimized the risk stratification of patients with adenoma for appropriate surveillance colonoscopy intervals.

Adherence to surveillance guidelines after removal of colorectal adenomas: a large, community-based study.

OBJECTIVE: To determine adherence to recommended surveillance intervals in clinical practice. DESIGN: 2997 successive patients with a first adenoma diagnosis (57% male, mean age 59 years) from 10 hospitals, who underwent colonoscopy between 1998 and 2002, were identified via Pathologisch Anatomisch Landelijk Geautomatiseerd Archief: Dutch Pathology Registry. Their medical records were reviewed until 1 December 2008. Time to and findings at first surveillance colonoscopy were assessed. A surveillance colonoscopy occurring within ± 3 months of a 1-year recommended interval and ± 6 months of a recommended interval of 2 years or longer was considered appropriate. The analysis was stratified by period per change in guideline (before 2002: 2-3 years for patients with 1 adenoma, annually otherwise; in 2002: 6 years for 1-2 adenomas, 3 years otherwise). We also assessed differences in adenoma and colorectal cancer recurrence rates by surveillance timing. RESULTS: Surveillance was inappropriate in 76% and 89% of patients diagnosed before 2002 and in 2002, respectively. Patients eligible under the pre-2002 guideline mainly received surveillance too late or were absent (57% of cases). For patients eligible under the 2002 guideline surveillance occurred mainly too early (48%). The rate of advanced neoplasia at surveillance was higher in patients with delayed surveillance compared with those with too early or appropriate timed surveillance (8% vs 4-5%, p<0.01). CONCLUSIONS: There is much room for improving surveillance practice. Less than 25% of patients with adenoma receive appropriate surveillance. Such practice seriously hampers the effectiveness and efficiency of surveillance, as too early surveillance poses a considerable burden on available resources while delayed surveillance is associated with an increased rate of advanced adenoma and especially colorectal cancer.

Features of adenoma and colonoscopy associated with recurrent colorectal neoplasia based on a large community-based study.

BACKGROUND & AIMS: We investigated adenoma and colonoscopy characteristics that are associated with recurrent colorectal neoplasia based on data from community-based surveillance practice. METHODS: We analyzed data of 2990 consecutive patients (55% male; mean age 61 years) newly diagnosed with adenomas from 1988 to 2002 at 10 hospitals throughout The Netherlands. Medical records were reviewed until December 1, 2008. We excluded patients with hereditary colorectal cancer (CRC) syndromes, a history of CRC, inflammatory bowel disease, or without surveillance data. We analyzed associations among adenoma number, size, grade of dysplasia, villous histology, and location with recurrence of advanced adenoma (AA) and nonadvanced adenoma (NAA). We performed a multivariable multinomial logistic regression analysis to estimate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: During the surveillance period, 203 (7%) patients were diagnosed with AA and 954 (32%) patients with NAA. The remaining 1833 (61%) patients had no adenomas during a median follow-up of 48 months. Factors associated with AA during the surveillance period included baseline number of adenomas (ORs ranging from 1.6 for 2 adenomas; 95% CI: 1.1-2.4 to 3.3 for ≥5 adenomas; 95% CI: 1.7-6.6), adenoma size ≥10 mm (OR = 1.7; 95% CI: 1.2-2.3), villous histology (OR = 2.0; 95% CI: 1.2-3.2), proximal location (OR = 1.6; 95% CI: 1.2-2.3), insufficient bowel preparation (OR = 3.4; 95% CI: 1.6-7.4), and only distal colonoscopy reach (OR = 3.2; 95% CI: 1.2-8.5). Adenoma number had the greatest association with NAA. High-grade dysplasia was not associated with AA or NAA. CONCLUSIONS: Large size and number, villous histology, proximal location of adenomas, insufficient bowel preparation, and poor colonoscopy reach were associated with detection of AA during surveillance based on data from community-based practice. These characteristics should be used jointly to develop surveillance policies for adenoma patients.

Interpretation and adherence to the updated risk-stratified guideline for colonoscopy surveillance after polypectomy - a nationwide survey.

Background and study aims Low adherence to the Dutch guideline for colonoscopy surveillance after polypectomy led to release of a new guideline in 2013. This new guideline was risk-stratified at a more detailed level than the previous one to achieve more efficient use of colonoscopy resources. This study assessed the feasibility of the risk-stratified guideline by evaluating correct interpretation of and adherence to this guideline. Methods Based on semi-structured interviews with 10 gastroenterologists, we developed an online survey to evaluate gastroenterologists' recommendations for surveillance in 15 example cases of patients with polyps. If recommended intervals differed from the new guideline, respondents were asked to indicate their motives for doing so. Results Ninety-one of 592 (15.4 %) invited gastroenterologists responded to at least one case, of whom 84 (14.2 %) completed the survey. Gastroenterologists gave a correct recommendation in a median of 10 of 15 cases and adherence per case ranged from 14 % to 95 % (median case 76 %). The two cases that addressed management of serrated polyps were least often answered correctly (14 % and 28 % correct answers). Discrepancies were mainly due to misinterpretation of the guideline with respect to serrated polyps (48 %) or misreading of the questions (30 %). Conclusions Median adherence to the updated colonoscopy surveillance guideline of 76 % seems reasonable, and is higher than adherence to the previous guideline (range: 22 %-80 %, median 59 %). This shows that detailed (more complex) risk stratification for designation of a surveillance interval is feasible. Adherence could potentially be improved by clarifying correct interpretation of serrated polyps.

Opposing associations of serum n-3 and n-6 polyunsaturated fatty acids with colorectal adenoma risk: an endoscopy-based case-control study.

Several human and animal studies have shown that n-3 polyunsaturated fatty acids (PUFA) might be associated with a decreased risk, whereas other studies showed that n-6 PUFA may be associated with an increased risk of colorectal cancer. However, results from these studies are not consistent. We evaluated the associations between serum n-3 and n-6 PUFA levels and colorectal adenoma risk in an endoscopy-based case-control study, conducted in The Netherlands between 1997 and 2002. We included 363 cases of colorectal adenomas and 498 adenoma-free controls. Serum fatty acids were measured in cholesteryl esters. Logistic regression models were used to calculate odds ratios (OR), which were adjusted for age, gender and alcohol intake. Total serum n-3 PUFA levels were inversely associated with colorectal adenoma risk, the OR comparing the third tertile with the first tertile was 0.67 [95% confidence interval (CI) 0.46-0.96, p for trend = 0.03]. Serum eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3) and the n-3/n-6 ratio were inversely associated with colorectal adenoma risk, but these were not statistically significant. In contrast, the risk of colorectal adenomas was increased by total n-6 PUFA with an OR of 1.68 (95% CI, 1.17-2.42, p for trend = 0.006) and by linoleic acid (LA; C18:2n-6) with an OR of 1.65 (95% CI, 1.15-2.38, p for trend = 0.007). This is the first observational study that simultaneously finds an inverse association of serum n-3 PUFA and a positive association of n-6 PUFA with colorectal adenoma risk.