Nationwide Colorectal Cancer Screening Program Research Articles

Impact of bowel preparation quality on colonoscopy findings and colorectal cancer deaths in a nation-wide colorectal cancer screening program.

Impact of bowel preparation quality on colonoscopy findings and colorectal cancer deaths in a nation-wide colorectal cancer screening program.

Initial Impact of National CRC Screening on Incidence and Advanced Colorectal Cancer

Screening for colorectal cancer (CRC) aims to decrease CRC incidence and mortality. Biennial fecal immunochemical test screening started in the Netherlands in 2014 for individuals 55-75 years of age. This study investigated the effect of screening on stage-specific incidence, with focus on stage III and IV CRC. Inhabitants diagnosed with CRC in 2009-2018 were included. CRC incidence per stage, year, and detection method (ie, screen-detected vs clinically detected) was evaluated. Patient, tumor, and treatment characteristics, and survival of patients with stage III and IV CRC, were compared according to the detection method. Included were 140,649 CRCs in 136,882 patients. An initial peak of stage I-III CRC diagnoses after initiation of screening was followed by a continuous decrease within screening-eligible ages. Total CRC incidence remained higher than before screening, although stage II and IV CRC incidence decreased below prescreening levels. Screen-detected CRCs were significantly more frequently located in the left-sided colon (stage III; 43.7% vs 30.9%; stage IV: 45.1% vs 36.1%), and the primary tumor resection rate was higher (stage III colon: 99.8% vs 99.0%, rectum: 97.3% vs 89.7%; stage IV colon: 65.4% vs 56.6%, rectum: 47.3% vs 33.5%). Patients with screen-detected stage IV CRC had significantly more often single-organ metastases (74.5% vs 57.0%; P < .001) and more frequently received treatment with curative intent (colon: 41.3% vs 27.4%; rectum: 33.8% vs 24.6%). Overall survival significantly improved for patients with screen-detected CRCs (stage III: P < .001; stage IV: P < .001). Five years after the start of a nationwide CRC screening program, a decrease in stage II and IV CRC incidence was observed. Patients with screen-detected stage III and stage IV CRC had less extensive disease and improved survival compared with those with clinically detected CRC.

Queue hurdle Coxian phase-type model for two-stage process of population-based cancer screening

The quality assurance of two-stage population-based cancer screening program is determined by arrival rate (attending screening), positive rate (determined by the criteria of screening test), the compliance and the waiting time (WT) for confirmatory diagnosis in those screened as positive. These parameters were correlated between the process of screening procedures and the effectiveness of screening program. To capture such an inter-dependence of these parameters and quantify the effectiveness of program, we proposed a Queue hurdle Coxian phase-type (QH-CPH) model to estimate the arrival rate of screenees with the Poisson Queue process and the compliance rate of confirmatory diagnosis with the hurdle model, and also to identify the hidden states of WT that is affected by the capacity of health care and relevant covariates (such as demographic features and geographic areas) with the Coxian phase-type (CPH) process. We applied the proposed QH-CPH model to Taiwanese nationwide colorectal cancer screening program data for estimating the arrival rate and the probability of not complying with colonoscopy and classifying the compliers into two hidden states, short-waiting phase and long-waiting phase for colonoscopy. Significant covariates responsible for three processes were also identified by using the proportional hazards regression forms. A simulation study was further performed to assess the joint effect of these parameters on WT through a series of scenarios. The proposed QH-CPH model can provide an insight into the optimal and the practical design on population-based cancer screening for health policy-makers given the limited health care resources and capacity.

The effectiveness of colorectal cancer screening for cancer survivors.

e16091 Background: Colorectal cancer (CRC) is one of the highest-incident neoplasms in many countries. Although the incidence of CRC is increasing gradually, the mortality rate has not increased due to early detection and multidisciplinary treatment. CRC screening programs, including colonoscopy and fecal occult blood tests, have been reducing CRC-related mortality worldwide. In Taiwan, the CRC screening program uses a biennial fecal immunochemical test (FIT) as the initial screening tool. FIT-positive participants receive a colonoscopy as a CRC confirmation examination. Cancer survivors have a higher incidence of secondary primary malignancies. Methods: We conducted a nationwide population-based study in Taiwan. The cancer survivors with FIT in the Nationwide Colorectal Cancer Screening (NCCS) Program between January 2010 and September 2014 were enrolled as the study group. The patients aged under 50, diagnosed with CRC before the FIT were excluded. The screening participants without a cancer history were served as the comparison group. The primary endpoint was CRC diagnosis within six months after a FIT. The cancer diagnosis was identified by using Taiwan Cancer Registry. The ratios of positive FIT, confirmatory colonoscopy, and CRC diagnosis in the cancer survivors and the comparison cohort were calculated and compared. Analyses were adjusted for participants’ characteristics by using multilevel logistic regression models. Results: We identified 288,919 cancer survivors who participated in the NCCS Program. Of them, 41.1% were male and the median age was 59 (interquartile ranges 54–64). There were 417,907 FITs performed in the study cohort. The FIT positive rates were 11.3% and 7.4% in the study and comparison groups, respectively (OR 1.59 95% CI 1.57–1.60). Of the FIT positive participants, 50.5% and 52.3% received confirmatory colonoscopy or the related examinations within six months, respectively (OR 0.93 95% CI 0.91–0.95). Then 3.0% and 4.4% of those receiving confirmatory colonoscopy were diagnosed with CRC in the study and comparison groups, respectively (OR 0.68 95% CI 0.63–0.74). After adjustment for age, sex, income, a family history of CRC, and comorbidities, the cancer survivors in this screening program had a similar rate of CRC diagnosis compared with those without antecedent malignancies (adjusted OR: 0.97, 95% CI 0.87–1.08). Conclusions: Although the cancer survivors had a higher rate of positive FIT, the CRC diagnosed by the screening did not increase. We further identified the risk factors associated with CRC in the cancer survivors.

Rank-Based Fecal Hemoglobin Concentration for Assessing Colorectal Neoplasms of National-Wide Colorectal Cancer Screening in Taiwan

Background: Fecal hemoglobin concentration has shown potential of predicting colorectal cancer and colorectal adenoma. Accordingly, it is of great interest to use fecal hemoglobin concentration to stratify population into risk groups of colorectal disease. Aim: This study aims to predict the risk of colorectal neoplasia by using quantitative fecal hemoglobin concentration with a rank-based method. Methods: Using data from Taiwanese nationwide colorectal cancer screening program between 2004 to 2009 following up until 2012, fecal hemoglobin concentration regarded as the ordinal outcome was used to predict the risk of colorectal adenoma. Accelerated failure time model on fecal hemoglobin was used to evaluate the differences across 4 categories of outcome, including colorectal cancer, advanced adenoma, nonadvanced adenoma, and normal colon. We converted the adjusted percentile values of each group of colorectal neoplasia into the corresponding risk with Bayesian underpinning. Results: The adjusted median fecal hemoglobin concentration of nonadvanced adenoma was 57.0, advanced adenoma was 82.4, and colorectal cancer was 163.1 µg/g feces compared with normal colon. The corresponding risks of 2 groups when the fecal hemoglobin concentration reached the median were 4.0%, 4.8%, and 29.5%. Risk of reaching other percentile of 2 groups of colorectal neoplasm can be acquired on the basis of adjusted percentile value of fecal hemoglobin. Conclusion: Based on quantitative fecal hemoglobin concentration and survival model analysis, we estimated the risk of developing colorectal neoplasia by percentile of fecal hemoglobin concentration.

Rolling-out Screening Volume Affecting Compliance Rate and Waiting Time of FIT-based Colonoscopy.

The population-based colorectal cancer screening program with fecal immunochemical test (FIT) from the inaugural period to the rolling-out period may create a higher demand for colonoscopies, but such a change has not been quantified. We intended to assess the change in the compliance rate and the waiting time (WT) for a colonoscopy and the associated geographic and institutional variations across the 2 periods. Data from the Taiwanese nationwide colorectal cancer screening program were analyzed. The data included a total of 46,235 FIT-positive cases of 1,258,560 tests in the inaugural period (2004 to 2009) and 270,700 FIT-positive cases of 3,723,789 tests in the rolling-out period (2010 to 2013). The compliance rate and WT for colonoscopy after positive FIT was ascertained and compared between the 2 periods. The rolling-out period resulted in a decline of 16.0% for compliance rate and yielded an additional 1,778,499 waiting days with variation across geography and institution. After adjusting for relevant factors, a decrease in compliance rate by 8.5% and an increase of 714,648 waiting days were still noted. In the rolling-out period, a remarkable decline in compliance rate by 9.8% was found in middle Taiwan, and the longest WT (1,260,109 d) was observed in southern Taiwan. Screening at public health centers led to a 19% decrease in compliance rate and an increase of 2,546,746 waiting days. The decrease in compliance rate and an increase in the WT with variation across geography and institution resulting from the increased volume of rolling-out FIT screening provide an insight into optimal resource allocation of clinical capacity for colonoscopy.

Quantitative Assessment on Waiting Time in Quality Assurance of Screening Program With Application to Taiwanese Population-Based Organized Service Colorectal Cancer Screening

Background: In a population-based organized service colorectal cancer (CRC) screening program, waiting time for confirmatory diagnosis for those who screened as positive test would be affected by coverage rate, positive rate, and compliance rate given clinical capacity of different settings. Long waiting time might cause the anxiety of patient and affect the quality of life. It is an essential index in the quality assurance of screening program. Aim: We aim to project the waiting time in different scenarios by changing the joint effect of these 3 factors (coverage rate, positive rate, and compliance rate). Methods: We proposed a stochastic process for modeling a complicated structure of screening data containing arrival rate for attending screening (coverage rate), positive rate, compliance rate, and waiting time for confirmatory diagnosis. It was applied to Taiwanese nationwide CRC screening program during the period of 2004 to 2009. The estimated parameters were used to project the waiting time by changing different scenarios. Results: Given positive rate and compliance rate, the waiting time was lengthened with increasing coverage rate. Under the similar scenario with Taiwanese nationwide population-based screening (7% of positive rate and 60% of compliance), the waiting time expanded from 10 days to 101 days as the coverage rate increased by 10-fold (from 5% to 50%). If the referral policy allows 2 months of waiting time for follow-up confirmatory, a 3-year CRC screening program can reach to 90% of coverage rate. If positive rate increases as a result of the cutoff value or compliance rate is enhanced, the waiting time can be prolonged in a quantitative manner. Conclusion: Waiting time for confirmatory examination usually plays an important role in the assessment of the quality assurance of screening program. After considering the change of 3 joint effects on coverage rate, positive rate, and compliance rate, we can project the waiting time and provide a quantitative assessment on referral policy to improve the quality of service for decision-maker.

The impact of water-aided methods on pain reduction and adenoma detection rate during colonoscopy

With the nationwide colorectal cancer screening program in place in Taiwan, there is an urgent need to promote techniques with a positive impact on adenoma detection rate (ADR) to minimize the risk of interval cancers. Despite widespread use of sedation, many patients in Taiwan still undergo unsedated or minimally sedated colonoscopy. Techniques that minimize pain will enhance the experience of colonoscopy, and facilitate participation in screening and surveillance. A review of water-aided colonoscopy is appropriate at this time. Water exchange (WE), in particular, appears to be able to meet the needs of colonoscopy patients in Taiwan. Water-aided methods are distinguished into water immersion (WI) and WE by the timing of removal of infused water—WI during withdrawal and WE during insertion. Both methods are typically performed with air pump turned off during the insertion phase of colonoscopy and thus are reported to produce less insertion pain as compared with traditional air insufflation (AI). Some colonoscopists do not require air exclusion with WI. The removal of water during insertion phase of colonoscopy, coupled with suctioning of residual air pockets, further enhance the pain reduction by WE. Head-to-head comparison of AI, WI, and WE has shown that WE reduced insertion pain to a greater extent than WI. Recent studies also showed that WE produced less insertion pain, with more patients completing colonoscopy without pain as compared with carbon dioxide (CO2) insufflation. WE also provides salvage cleaning during insertion and reduces distraction to inspection during withdrawal, both of which might help the colonoscopist to find more polyps. In recent randomized controlled trials comparing AI, WI, and WE, the secondary outcomes of overall ADR and right colon or proximal colon ADR were in favor of WE, but not WI. In conclusion, with practice WE is an easy and inexpensive way of insertion during colonoscopy. Its ability to reduce insertion pain and increase ADR may help improve the quality of colonoscopy. Colonoscopists in Taiwan should consider contributing to a study to assess whether the increase in ADR by WE is reproducible, and if so, whether the occurrence of interval cancers can be reduced or avoided.

465 - Comparison of Diagnostic Yield of two Brands of Fecal Immunochemical Tests within the Dutch Nationwide Colorectal Cancer Screening Program

465 - Comparison of Diagnostic Yield of two Brands of Fecal Immunochemical Tests within the Dutch Nationwide Colorectal Cancer Screening Program

Increase your adenoma detection rate without using fancy adjunct tools.

The correlation between a low adenoma detection rate (ADR) and interval cancers (ICs) has made ADR one of the most important quality indicators for colonoscopy. Data from nation-wide colorectal cancer (CRC) screening programs showed that there is room for improvement in ADR in order to reduce ICs in Taiwan. Measures with and without adjunct tools have been shown to have the potential to increase ADR, with the latter being more convenient to apply without additional cost. Optimal withdrawal techniques coupled with sufficient withdrawal time, training endoscopists with emphasis on recognition of subtle characteristics of flat lesions, dynamic position changes during the withdrawal phase, removing small polyps found during insertion, and retroflexion in the right colon have all been associated with increased ADR. In particular, water exchange (WE), which is characterized using water in lieu of air and suction removal of infused water during insertion, appears to meet the needs of colonoscopy patients in Taiwan. Analyses of both primary and secondary outcome variables of recently published studies have consistently shown that WE yields higher ADR than traditional air insufflation, even in propofol-sedated patients. Colonoscopists participating in the nationwide CRC screening program in Taiwan should consider applying one or more of the above measures to improve ADR and hopefully reduce ICs.

Perceptions of colorectal cancer screening and recommendation behaviors among physicians in Korea

BackgroundPhysician recommendations for colorectal cancer (CRC) screening have consistently been shown to be a strong predictor of screening. The aim of this study was to investigate perceptions of CRC screening modalities and recommendation behaviors among physicians in Korea.MethodsA cross-sectional, nationally representative survey conducted between November 2013 and February 2014. In total, 379 physicians (241 primary care physicians and 138 physicians affiliated with the Korean Association for the Study of Intestinal Diseases responded to this survey (overall response rate of 31.4%).ResultsAbout 29% of all respondents “always” recommended and about 67% “sometimes” recommended CRC screening. Colonoscopy was perceived as an effective primary screening tool for CRC, and 80% of the physicians recommended colonoscopy for CRC screening. Only 7% recommended FOBT. In multivariate analysis, recommending FOBT was associated with stronger belief in the screening efficacy of FOBT (aOR 3.70, 95% CI 2.09, 6.57), weaker belief in the screening efficacy of colonoscopy (aOR 0.29, 95% CI 0.12, 0.69), and negative decisional balance for colonoscopy screening (aOR 0.82, 95% CI 0.71, 0.95).ConclusionsAlthough FOBT is provided free-of-charge through a nationwide CRC screening program, colonoscopy was more commonly recommended and preferred by physicians.

Survival rates and predictors of survival among colorectal cancer patients in a Malaysian tertiary hospital

BackgroundColorectal cancer is the third most commonly diagnosed malignancy and the fourth leading cause of cancer-related death globally. It is the second most common cancer among both males and females in Malaysia. The economic burden of colorectal cancer is likely to increase over time owing to its current trend and aging population. Cancer survival analysis is an essential indicator for early detection and improvement in cancer treatment. However, there was a scarcity of studies concerning survival of colorectal cancer patients as well as its predictors. Therefore, we aimed to determine the 1-, 3- and 5-year survival rates, compare survival rates among ethnic groups and determine the predictors of survival among colorectal cancer patients.MethodsThis was an ambidirectional cohort study conducted at the University Malaya Medical Centre (UMMC) in Kuala Lumpur, Malaysia. All Malaysian citizens or permanent residents with histologically confirmed diagnosis of colorectal cancer seen at UMMC from 1 January 2001 to 31 December 2010 were included in the study. Demographic and clinical characteristics were extracted from the medical records. Patients were followed-up until death or censored at the end of the study (31st December 2010). Censored patients’ vital status (whether alive or dead) were cross checked with the National Registration Department. Survival analyses at 1-, 3- and 5-year intervals were performed using the Kaplan-Meier method. Log-rank test was used to compare the survival rates, while Cox proportional hazard regression analysis was carried out to determine the predictors of 5-year colorectal cancer survival.ResultsAmong 1212 patients, the median survival for colorectal, colon and rectal cancers were 42.0, 42.0 and 41.0 months respectively; while the 1-, 3-, and 5-year relative survival rates ranged from 73.8 to 76.0%, 52.1 to 53.7% and 40.4 to 45.4% respectively. The Chinese patients had the lowest 5-year survival compared to Malay and Indian patients. Based on the 814 patients with data on their Duke’s staging, independent predictors of poor colorectal cancer (5-year) survival were male sex (Hazard Ratio [HR]: 1.41; 95% CI: 1.12, 1.76), Chinese ethnicity (HR: 1.41; 95% CI: 1.07,1.85), elevated (≥ 5.1 ng/ml) pre-operative carcino-embryonic antigen (CEA) level (HR: 2.13; 95% CI: 1.60, 2.83), Duke’s stage C (HR: 1.68; 95% CI: 1.28, 2.21), Duke’s stage D (HR: 4.61; 95% CI: 3.39, 6.28) and emergency surgery (HR: 1.52; 95% CI: 1.07, 2.15).ConclusionsThe survival rates of colorectal cancer among our patients were comparable with those of some Asian countries but lower than those found in more developed countries. Males and patients from the Chinese ethnic group had lower survival rates compared to their counterparts. More advanced staging and late presentation were important predictors of colorectal cancer survival. Health education programs targeting high risk groups and emphasizing the importance of screening and early diagnosis, as well as the recognition of symptoms and risk factors should be implemented. A nationwide colorectal cancer screening program should be designed and implemented to increase early detection and improve survival outcomes.

Faecal haemoglobin concentration influences risk prediction of interval cancers resulting from inadequate colonoscopy quality: analysis of the Taiwanese Nationwide Colorectal Cancer Screening Program

ObjectivesInterval colorectal cancer (CRC) after colonoscopy may affect effectiveness and cost-effectiveness of screening programmes. We aimed to investigate whether and how faecal haemoglobin concentration (FHbC) of faecal immunochemical testing (FIT)...

Constipation is not associated with diverticular disease – Analysis of 976 patients

BackgroundIn the light of controversial data in the literature, the present study was designed to evaluate potential associations between colonic diverticular disease, constipation and quality of life. DesignWe prospectively enrolled 976 consecutive patients, who participated in the nationwide colorectal cancer screening program in four medical centers between 2008 and 2009. All patients underwent full colonoscopy and completed a standardized questionnaire. The severity of constipation was assessed by the validated Wexner constipation score. Quality of Life (QOL) was evaluated by the SF-12 health score. ResultsThe median age was 62 years (range 22–90) and the male to female ratio was 1:1. Colonic diverticular disease was found in 290 participants (30%). Age, body mass index and diabetes mellitus were significantly associated with the presence of diverticular disease (p < 0.0001, p = 0.0007 and p = 0.0178).The median constipation score in patients with diverticular disease was 3 (range 0–18), and comparable to patients without diverticula (p = 0.1073). The physical component summary of the SF-12 was significantly reduced in patients with diverticular disease (p = 0.0038). ConclusionThis large population based study revealed no association between colonic diverticular disease and constipation. Notably, the presence of diverticular disease significantly impacts quality of life.

Preferences and acceptance of colorectal cancer screening in Thailand.

Colorectal cancer (CRC) is now common in Thailand with an increase in incidence over time. Health authorities are planning to implement a nationwide CRC screening program using fecal immunochemical test (FIT) as a primary screening tool. This study aimed to estimate preferences and acceptance of FIT and colonoscopy, explore factors influencing the acceptance, and investigate reasons behind choosing and rejecting to screen before the program was implemented. Patients aged 50-69, visiting the primary care unit during the study period, were invited to join this study. Patients with a history of cancer or past CRC screening were excluded. Face-to-face interviews were conducted. Subjects were informed about CRC and the screening tests: FIT and colonoscopy. Then, they were asked for their opinions regarding the screening. The total number of subjects was 437 (86.7% response rate). Fifty-eight percent were females. The median age was 58 years. FIT was accepted by 74.1% of subjects compared to 55.6% for colonoscopy. The acceptance of colonoscopy was associated with perceived susceptibility to CRC and family history of cancer. No symptoms, unwilling to screen, healthy, too busy and anxious about diagnosis were reasons for refusing to screen. FIT was preferred for its simplicity and non-invasiveness compared with colonoscopy. Those rejecting FIT expressed a strong preference for colonoscopy. Subjects chose colonoscopy because of its accuracy; it was refused for the process and complications. If the screening program is implemented for the entire target population in Thailand, we estimate that 106,546 will have a positive FIT, between 8,618 and 12,749 identified with advanced adenoma and between 2,645 and 3,912 identified with CRC in the first round of the program.

Tu1087 Comparison of Outreach and Inreach Approaches in a Nationwide Colorectal Cancer Screening Program Using the Fecal Immunochemical Test

Tu1087 Comparison of Outreach and Inreach Approaches in a Nationwide Colorectal Cancer Screening Program Using the Fecal Immunochemical Test

Difference in Performance of Fecal Immunochemical Tests With the Same Hemoglobin Cutoff Concentration in a Nationwide Colorectal Cancer Screening Program

We investigated whether 2 quantitative fecal immunochemical tests (FITs) with the same cutoff concentration of fecal hemoglobin perform equivalently in identifying patients with colorectal cancer (CRC). A total of 956,005 Taiwanese subjects, 50 to 69 years old, participated in a nationwide CRC screening program to compare results from 2 FITs; 78% were tested using the OC-Sensor (n = 747,076; Eiken Chemical Co, Tokyo, Japan) and 22% were tested using the HM-Jack (n = 208,929; Kyowa Medex Co Ltd, Tokyo, Japan), from 2004 through 2009. The cutoff concentration for a positive finding was 20 μg hemoglobin/g feces, based on a standardized reporting unit system. The tests were compared using short-term and long-term indicators of performance. The OC-Sensor test detected CRC in 0.21% of patients, with a positive predictive value of 6.8%. The HM-Jack test detected CRC in 0.17% of patients, with a positive predictive value of 5.2%. The rate of interval cancer rate was 30.7/100,000 person-years among subjects receiving the OC-Sensor test and 40.6/100,000 person-years among those receiving the HM-Jack test; there was significant difference in test sensitivity (80% vs 68%, P = .005) that was related to the detectability of proximal CRC. After adjusting for differences in city/county, age, sex, ambient temperature, and colonoscopy quality, significant differences were observed between the tests in the positive predictive value for cancer detection (adjusted relative risk = 1.29; 95% confidence interval, 1.14-1.46) and the rates of interval cancer (0.75; 95% confidence interval, 0.62-0.92). Although each test was estimated to reduce CRC mortality by approximately 10%, no significant difference in mortality was observed when the 2 groups were compared. Different brands of quantitative FITs, even with the same cutoff hemoglobin concentration, perform differently in mass screening. Population-level data should be gathered to verify the credibility of quantitative laboratory findings.

Costs and benefits of an organized fecal immunochemical test-based colorectal cancer screening program in the United States.

Despite clear recommendations and evidence linking colorectal cancer screening to lower incidence and mortality, > 40% of adults are not up to date with screening. Existing domestic and international models of organized cancer screening programs have been effective in increasing screening rates. Implementing an organized, evidence-based, national screening program may be an effective approach to increasing screening rates. In the current study, the authors estimated the initial investment required and the cost per person screened of a nationwide fecal immunochemical test (FIT)-based colorectal cancer screening program among adults aged 50 years to 75 years. The initial additional investment required was estimated at $277.9 to $318.2 million annually, with an estimated 8.7 to 9.4 million individuals screened at a cost of $32 to $39 per person screened. The program was estimated to prevent 2900 to 3100 deaths annually. The results of the current study indicate that implementing a national screening program would make a substantial public health impact at a moderate cost per person screened. Results from this analysis may provide useful information for understanding the public health benefit of an organized screening delivery system and the potential resources required to implement a nationwide colorectal cancer screening program, and help guide decisions about program planning, design, and implementation.

Endoscopists Are Independent Predictors of Adenoma Detection Rates in a Colorectal Cancer Screening Program Based On Biennial Fecal Occult Blood Test (FOBT): A Population-Based Study

Background and Aim: Whilst the prevalence of neoplasia is known to be high at colonoscopy performed after a positive FOBT result, little is known about putative variations in neoplasia detection rates between endoscopists in such cases. We therefore aimed to assess the differences between endoscopists in a population-based study (938,947 inhabitants) with a high (>50%) compliance rate for screening. Patients and Methods: We calculated the detection rates for cancer, any adenoma, ≥ 2 adenomas, ≥ 3 adenomas, adenoma ≥ 10 mm for each of the 18 endoscopists enrolled in the study: those who participated to the two first rounds of the screening program and performed at least 30 colonoscopies at each screening round. Crude neoplasia detection rates and adjusted rates to patients' age and gender were calculated for each endoscopist. Odds ratios were calculated for each endoscopist by comparing him to the endoscopist with the lowest adjusted neoplasia detection rate. Differences between endoscopists were determined at each round and after pooling data of both rounds. Differences were assessed by multivariate analysis for each round (results not shown) and for pooled data. Results: the 18 endoscopists performed 3462 of 4136 (84%) colonoscopies following FOBT (1936 and 1526 at 1st and 2nd round, respectively). At 1st round, adjusted detection rates ranged among endoscopists from 7.0% to 17.8% for cancer, 6.0% to 48.3% for any adenoma, 4.9% to 24.4% for ≥2 adenomas, 2.8% to 13.3% for ≥3 adenomas and 8.2% to 30.4% for large adenoma. Similar findings were depicted at 2nd round. Regarding pooled data, odds ratios ranged among endoscopists from 1.21 to 2.85 for cancer (4/17 significantly > 1) and from 1.19 to 2.77 for any adenoma detection (8/17 significantly > 1). No statistical correlation was observed between endoscopists' performances and either their age or colonoscopy volume. Multivariate analysis indicated that endoscopists (besides patients' age and gender) were independent predictors of all categories of adenoma detection including large adenomas (p = 0.015), but not of cancer detection (p = 0.38). Conclusions: This study shows for the first time that performances in detecting all categories of adenomas, including large adenomas, but not cancer vary greatly among endoscopists participating to a nationwide colorectal cancer screening program based on FOBT. While assuming that most endoscopists performed careful examinations after a positive FOBT result, these findings emphasize the need for understanding the reasons for observed differences in the real life and for defining quality indicators of colonoscopy following FOBT.