Evelien Dekker

Academisch Medisch Centrum Universiteit van Amsterdam, Amsterdamo, North Holland, Netherlands

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Publications (271)2102.18 Total impact

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    ABSTRACT: Background and aims: Patients with longstanding colitis have an increased risk for developing CRC. Although the risk for ulcerative colitis is well established, for Crohn's disease data are contradictory. This study aims to determine the number Crohn's patients with dysplasia undergoing surveillance, and assess the diagnostic accuracy of chromoendoscopy (CE) combined with integrated confocal laser endomicroscopy (iCLE) for differentiating dysplastic versus non-dysplastic lesions. Methods: Patients with longstanding Crohn's colitis undergoing surveillance colonoscopy were included in this multicenter, prospective, cohort study. Surveillance was performed with CE and lesions were assessed with iCLE for differentiation. All lesions were removed and send in for pathology as reference standard. Results: Between 2010 and 2014, 61 Crohn's patients were included in 5 centers. Seventy-two lesions, of which 7 dysplastic, were detected in 6 patients (dysplasia detection rate: 9.8%), none included high-grade dysplasia or cancer. Combined CE with iCLE for differentiating neoplastic from non-neoplastic lesions, had an accuracy of 86.7% (95% CI, 78.1-95.3), sensitivity of 42.9% (95% CI, 11.8-79.8) and specificity of 92.4% (95% CI, 80.9-97.6). For CE alone this was 80.3% (95% CI, 70.7-89.9), 28.6% (95% CI, 5.1-69.7) and 86.4% (95% CI, 80.9-97.6). The study terminated early due to frequent failure of the endoscopic equipment. Conclusion: This study shows a low incidence of dysplastic lesions found during surveillance colonoscopy in longstanding extensive Crohn's colitis. The accuracy of both CE alone and in combination with iCLE was relatively good, although the sensitivity for both was poor. Due to frequent failure iCLE has limited applicability in daily practice as a surveillance strategy.
    Gastrointestinal endoscopy 09/2015; DOI:10.1016/j.gie.2015.09.001 · 5.37 Impact Factor
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    ABSTRACT: Implementation of nationwide screening programs aims to decrease the disease burden of colorectal cancer (CRC) in the general population. Globally, most population screening programs for CRC are performed by either fecal occult blood test, flexible sigmoidoscopy or colonoscopy. For screening programs with colonoscopy as primary method, only circumstantial evidence from observational studies is available to prove its effectiveness, suggesting that colonoscopy effectively reduces CRC incidence and mortality. Currently, large randomized trials are being conducted to corroborate these findings. Besides the direct effect of a screening program for CRC, its protective effect is further enhanced by enrolment of patients that underwent polypectomy in surveillance programs. However, despite CRC screening and surveillance colonoscopies, interval CRCs still occur. Those are predominantly located in the right-sided colon and potential explanations, besides unfavorable tumor characteristics, are preventable operator-dependent factors relating to the quality of the colonoscopy procedure. In an effort to reduce differences in endoscopists' performance and thereby the occurrence of interval CRCs, quality indicators of colonoscopy have been introduced. In addition, emerging advanced colonoscopy techniques might contribute to the improvement in polyp detection and removal. The meticulous inspection of the colonic mucosa not only results in the detection of advanced and relevant lesions, but also in the removal of many diminutive and small lesions leading to an increasing number of surveillance colonoscopies, known as the "high-detection paradox". More data on the cost-effectiveness of high quality colonoscopy as a primary screening method and surveillance programs with intervals based on optimal risk-stratification are eagerly awaited. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Digestive Endoscopy 08/2015; DOI:10.1111/den.12533 · 2.06 Impact Factor
  • Evelien Dekker · Monique E van Leerdam
    Gastrointestinal endoscopy 08/2015; 82(2):334-336. DOI:10.1016/j.gie.2015.03.1903 · 5.37 Impact Factor
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    ABSTRACT: Objectives: Randomized trials demonstrated that chromoendoscopy is superior to white light endoscopy with random biopsy sampling (WLE) for the detection of dysplasia in patients with inflammatory bowel disease (IBD). Whether implementing chromoendoscopy can increase the detection of dysplasia in clinical practice is unknown. Methods: Patients with ulcerative colitis (UC) and Crohn's disease (CD) undergoing colonoscopic surveillance between January 2000 and November 2013 in three referral centers were identified using the patients' medical records. In recent years, the use of high-definition chromoendoscopy was adopted in all three centers using segmental pancolonic spraying of 0.1% methylene blue or 0.3% indigo carmine (chromoendoscopy group). Previously, surveillance was performed employing WLE with random biopsies every 10 cm (WLE group). The percentage of colonoscopies with dysplasia was compared between both groups. Results: A total of 440 colonoscopies in 401 patients were performed using chromoendoscopy and 1,802 colonoscopies in 772 patients using WLE. Except for a higher number of CD patients with extensive disease and more patients with a first-degree relative with colorectal cancer (CRC) in the chromoendoscopy group, the known risk factors for IBD-associated CRC were comparable between both groups. Dysplasia was detected during 48 surveillance procedures (11%) in the chromoendoscopy group as compared with 189 procedures (10%) in the WLE group (P=0.80). Targeted biopsies yielded 59 dysplastic lesions in the chromoendoscopy group, comparable to the 211 dysplastic lesions detected in the WLE group (P=0.30). Conclusions: Despite compelling evidence from randomized trials, implementation of chromoendoscopy for IBD surveillance did not increase dysplasia detection compared with WLE with targeted and random biopsies.
    The American Journal of Gastroenterology 07/2015; 110(7):1014-1021. DOI:10.1038/ajg.2015.63 · 10.76 Impact Factor
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    ABSTRACT: Background and study aims: Fecal immunochemical tests (FIT) are used to detect blood in feces, which might indicate the presence of colorectal neoplasia. The aim of this study was to investigate whether FIT results vary depending on the characteristics of colonic lesions. Patients and methods: This was a retrospective analysis of lesions detected in a cohort of asymptomatic individuals (aged 50 - 75 years) who were invited to participate in a FIT-based screening pilot in The Netherlands. The mean FIT result was compared across subgroups of individuals defined by histopathology of the most advanced lesion detected. In addition, the results were compared with data from a primary colonoscopy screening trial, in which participants also completed a FIT. Results: In three rounds of FIT-based screening, a total of 877 FIT-positive individuals underwent colonoscopy. Higher mean FIT results (hemoglobin [Hb]/g feces) were observed in individuals with carcinomas (199 μg Hb/g) and advanced adenomas (87 μg Hb/g) compared with participants with nonadvanced adenomas (50 μg Hb/g) or those with serrated lesions (46 μg Hb/g) (P < 0.001). In the primary colonoscopy trial, 1256 participants completed a FIT test and underwent colonoscopy. The number of participants with nonadvanced adenomas as the most advanced lesion was comparable between this group and the FIT-based screening group (20 % vs. 22 %). Conclusion: In FIT-based screening, the mean FIT results varied depending on the characteristics of the most advanced colonic lesion. The proportion of participants with a nonadvanced adenoma as the most advanced lesion was similar in the FIT-based screening group and in the primary colonoscopy screening group, suggesting that these lesions are coincidental findings rather than FIT-detected findings. www.trialregister.nl number NTR2755. © Georg Thieme Verlag KG Stuttgart · New York.
    Endoscopy 06/2015; DOI:10.1055/s-0034-1392412 · 5.05 Impact Factor
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    ABSTRACT: Background and study aims: The most frequently cited prevalence for serrated polyposis syndrome (SPS) is 1 in every 3000 people screened, but this value is debated. Additionally, changes in 2010 in the World Health Organization (WHO) diagnostic criteria for SPS might affect reported prevalence. An updated estimate of SPS prevalence is necessary to predict the number of cases in screening programs. Patients and methods: A systematic literature search was conducted in the PubMed, EMBASE, and Web of Science databases up to February 2014. Studies reporting the prevalence of SPS, as defined by WHO criteria, in screening populations were selected. Results: Six studies reported prevalence of SPS in screening populations, varying from 0 to 0.66 %. The highest prevalences (0.34 % and 0.66 %) were seen in studies from screening programs with patients pre-selected by fecal blood test. Primary colonoscopy-based screening programs, that have the lowest risk of bias, reported SPS prevalences ranging from 0 to 0.09 %. Across studies, 56 patients were diagnosed with SPS of whom 3 presented with synchronous colorectal cancer at index endoscopy. Conclusion: The true prevalence of SPS is unclear because of the risk of bias across studies, but is likely to be below 0.09 % as derived from primary colonoscopy screening programs. The prevalence in pre-selected screening populations after positive fecal testing is higher, with reported values of 0.34 % and 0.66 %. Large and high quality primary colonoscopy screening studies, reporting SPS prevalence in adequately described populations, are necessary for better estimation of the true prevalence of SPS in average-risk patients. © Georg Thieme Verlag KG Stuttgart · New York.
    Endoscopy 06/2015; DOI:10.1055/s-0034-1392411 · 5.05 Impact Factor
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    ABSTRACT: Conventional adenomas were traditionally thought to be the only precursors to colorectal cancer (CRC). Nowadays, also serrated polyps are acknowledged as precursor lesions for CRC, responsible for up to 30% of all CRCs and probably a larger percentage of interval CRCs after colonoscopy. In recent years, much research is being done to unravel the serrated neoplasia pathway. Endoscopic detection of serrated polyps is still a challenge for gastroenterologists, which is illustrated by large variations in detection rates of serrated polyps in the proximal colon. Clinical practice is further inhibited by poor optical differentiation of SSA/Ps from conventional adenomas and HPs and difficult delineation of those lesions, resulting in incomplete resection. The main focus of this review is to highlight recent advancements in endoscopic imaging techniques with regards to detection, differentiation and resection of serrated polyps.
    Baillière&#x027 s Best Practice and Research in Clinical Gastroenterology 06/2015; 29(4). DOI:10.1016/j.bpg.2015.05.009 · 3.48 Impact Factor
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    ABSTRACT: This study explored individuals' preferences for genetic testing for colorectal cancer (CRC) in a screening situation and their willingness to participate in genetic testing for Lynch syndrome, familial adenomatous polyposis (FAP), and familial colorectal cancer (FCC). For that purpose, 532 respondents aged 55-65 years completed a Discrete Choice Experiment. Using panel latent class models, the preferences for two screening situation characteristics (the probability of being genetically predisposed and the probability of developing CRC) and screening test characteristics (the frequency of preventive colonoscopies and CRC survival) were estimated. Based on these preferences, respondents' willingness to participate in the three screening initiatives was estimated. Lower-educated respondents and respondents who express serious anxiety and worries found colonoscopy frequency and the probability of developing CRC relatively more important and survival relatively less important compared with higher-educated respondents and respondents who express no anxiety and worries. These differences in preferences resulted in opposite preferences for participation in FCC and FAP screening. In conclusion, the general population is willing to participate in genetic screening for CRC. If individuals are suspected of genetic or familial CRC, they should at least be informed about their increased risk of being genetically predisposed and about the importance of participating in all preventive follow-up colonoscopies in order to maximize survival.European Journal of Human Genetics advance online publication, 3 June 2015; doi:10.1038/ejhg.2015.117.
    European journal of human genetics: EJHG 06/2015; DOI:10.1038/ejhg.2015.117 · 4.35 Impact Factor
  • Gut 06/2015; 64(Suppl 1):A52. DOI:10.1136/gutjnl-2015-309861.105 · 14.66 Impact Factor
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    ABSTRACT: Colorectal cancer (CRC) is considered a heterogeneous disease, both regarding pathogenesis and clinical behaviour. Four decades ago, the adenoma-carcinoma pathway was presented as the main pathway towards CRC, a conclusion that was largely based on evidence from observational morphological studies. This concept was later substantiated at the genomic level. Over the past decade, evidence has been generated for alternative routes in which CRC might develop, in particular the serrated neoplasia pathway. Providing indisputable evidence for the neoplastic potential of serrated polyps has been difficult. Reasons include the absence of reliable longitudinal observations on individual serrated lesions that progress to cancer, a shortage of available animal models for serrated lesions and challenging culture conditions when generating organoids of serrated lesions for in vitro studies. However, a growing body of circumstantial evidence has been accumulated, which indicates that ≥15% of CRCs might arise through the serrated neoplasia pathway. An even larger amount of post-colonoscopy colorectal carcinomas (carcinomas occurring within the surveillance interval after a complete colonoscopy) have been suggested to originate from serrated polyps. The aim of this Review is to assess the current status of the serrated neoplasia pathway in CRC and highlight clinical implications.
    Nature Reviews Gastroenterology &#38 Hepatology 05/2015; 12(7). DOI:10.1038/nrgastro.2015.73 · 12.61 Impact Factor
  • Gastrointestinal Endoscopy 05/2015; 81(5):AB208. DOI:10.1016/j.gie.2015.03.193 · 5.37 Impact Factor
  • Gastrointestinal Endoscopy 05/2015; 81(5):AB326-AB327. DOI:10.1016/j.gie.2015.03.1453 · 5.37 Impact Factor
  • Gastrointestinal Endoscopy 05/2015; 81(5):AB145. DOI:10.1016/j.gie.2015.03.1231 · 5.37 Impact Factor
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    ABSTRACT: The adenoma detection rate (ADR) is the most important surrogate quality parameter for colorectal cancer (CRC) prevention. However, serrated polyps also are precursors of CRC. Large, prospective studies comparing the detection rate of serrated polyps among endoscopists in an era of awareness about the malignant potential of serrated polyps have not yet been performed. We aimed to compare the proximal serrated polyp (PSP) detection rate and the clinically relevant serrated polyp (RSP) detection rate among endoscopists and to analyze the association between these parameters and the ADR. Colonoscopy data were retrieved in one expert center between January 2011 and July 2014 by using a structured reporting system, enabling prospective and automatic quality assessment. Endoscopists who performed at least 50 colonoscopies within the timeframe were included for analysis. Multivariate logistic regression was used to compare the ADR, PSP detection rate, and RSP detection rate among endoscopists. The association among these parameters was calculated by using the Pearson r correlation coefficient. All lesions were assessed by an expert pathologist. In total, 16 endoscopists and 2088 colonoscopies were included for analysis. The PSP detection rate ranged from 2.9% to 18.6% (mean 10.4%) among endoscopists. Corrected for confounders, the odds ratio to detect ≥1 PSP, compared with endoscopists with the highest detection rate, ranged from 0.79 (95% confidence interval [CI], 0.41-1.52) to 0.12 (95% CI, 0.03-0.55). The PSP detection rate was highly correlated with the RSP detection rate (ρ 0.94; P < .001), ranging from 4.3% to 20.9% (mean 13.9%). The PSP detection rate moderately correlated with the ADR (0.55; P = .03), which ranged from 23.2% to 49.2% (mean 35.2%). The PSP detection rate is widely variable among endoscopists, strongly correlated with the RSP detection rate, and moderately correlated with the ADR. These results suggest a high miss rate of RSPs among endoscopists with low rates of PSP detection. Future research should determine the association between endoscopists' PSP detection rates and the risk of interval cancer. Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.
    Gastrointestinal endoscopy 04/2015; DOI:10.1016/j.gie.2015.02.044 · 5.37 Impact Factor
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    ABSTRACT: The effectiveness of colorectal cancer screening programs based on the fecal immunochemical test (FIT) is influenced by program adherence during consecutive screening rounds. We aimed to evaluate the participation rate, yield, and interval cancers in a third round of biennial CRC screening using FIT and to compare those with the first and the second screening round. A total of 3566 average-risk individuals aged 50-75 years were invited to participate in a third round of biennial FIT-based CRC screening. All FIT positives were recommended to undergo colonoscopy. We merged our data with the national cancer registry in the Netherlands to identify all non-screen-detected cancers in our cohort. Of the invitees, 2142 (60%) returned the FIT in this third screening round, compared to 56% in the second round and 57% in the first round. Overall, 153 of the third-round participants (7.1%) had a positive FIT result, versus 7.9% in the second round and 8.1% in the first round (P=0.05). Of all FIT positives, 123 (80%) underwent colonoscopy. Within this group, 33 persons had advanced neoplasia. The predictive value of FIT positivity for advanced neoplasia was 27% (33/123), compared to 42% in the second round and 54% in the first round - a significant decline (P<0.01). In an FIT-based screening program, participation rates remained stable over consecutive biennial screening rounds, while the FIT positivity rate and positive predictive value for advanced neoplasia gradually declined. Cancers in non-participants are significantly more advanced in staging than cancers in participants in the first round of screening. Copyright © 2015 Elsevier Ltd. All rights reserved.
    04/2015; 39(3). DOI:10.1016/j.canep.2015.03.012
  • Gastroenterology 04/2015; 148(4):S-757-S-758. DOI:10.1016/S0016-5085(15)32589-0 · 16.72 Impact Factor
  • Gastroenterology; 04/2015
  • Gastroenterology 04/2015; 148(4):S-112. DOI:10.1016/S0016-5085(15)30385-1 · 16.72 Impact Factor
  • Gastroenterology 04/2015; 148(4):S-160. DOI:10.1016/S0016-5085(15)30537-0 · 16.72 Impact Factor
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    ABSTRACT: We developed and validated an online questionnaire to document familial cancer history, in order to facilitate the detection of persons with a familial or hereditary colorectal cancer (CRC) risk. The development of the self-administered online questionnaire for the assessment of familial and hereditary CRC risk was based on nationwide criteria for referral to genetic specialists due to a Lynch syndrome suspicion, as well as existing criteria for surveillance colonoscopies because of an increased risk of familial CRC. The questionnaire was validated at a private colonoscopy center. Patients scheduled for colonoscopy were enrolled (n = 150). Performance of the questionnaire was assessed by comparing referrals based on questionnaire data against referral decisions based on full pedigree data. In a second validation phase, referrals based on questionnaire data were compared with referrals based on data collected in a telephone interview. We also calculated inter-observer agreement in referral decisions. In the first validation phase, the questionnaire had a sensitivity of 90 % (95 % CI 55-98 %) at a specificity of 98 % (95 % CI 87-100 %) in identifying persons qualifying for referral. In the second validation phase, sensitivity was 100 % (95 % CI 63-100) at a specificity of 97 % (95 % CI 91-99 %). In both validation phases an inter-observer agreement of 100 % in referral decisions was achieved. The online questionnaire has a high sensitivity and specificity in identifying persons qualifying for referral because of suspected Lynch syndrome or familial CRC. Implementation of this tool in colonoscopy clinics can facilitate the detection of patients with hereditary or familial CRC.
    Familial Cancer 03/2015; 14(3). DOI:10.1007/s10689-015-9792-1 · 1.98 Impact Factor

Publication Stats

4k Citations
2,102.18 Total Impact Points


  • 2006–2015
    • Academisch Medisch Centrum Universiteit van Amsterdam
      • • Department of Gastroenterology and Hepatology
      • • Academic Medical Center
      Amsterdamo, North Holland, Netherlands
  • 2004–2015
    • University of Amsterdam
      • Department of Gastroenterology and Hepatology
      Amsterdamo, North Holland, Netherlands
  • 2012
    • Pontifical Catholic University of Chile
      CiudadSantiago, Santiago Metropolitan, Chile
    • Lyell McEwin Hospital
      Tarndarnya, South Australia, Australia
    • VU University Medical Center
      • Department of Gastroenterology and Hepatology
      Amsterdamo, North Holland, Netherlands
  • 2011
    • Technische Universität München
      München, Bavaria, Germany
  • 2009
    • Imperial College London
      Londinium, England, United Kingdom