Does a negative screening colonoscopy ever need to be repeated?

Colorectal cancer risk associated with hormone use varies by expression of estrogen receptor-β

The risk of colorectal cancer is reduced among users of oral contraceptives or menopausal hormone therapy, but associations with reproductive characteristics that are markers of a woman's endogenous hormone milieu have not been consistently observed. To help understand possible mechanisms through which exogenous and endogenous hormonal exposures are involved in colorectal cancer, we assessed the risk of these malignancies according to tumor expression of estrogen receptor-β (ESR2). In a population-based study of postmenopausal women (503 cases and 721 controls matched for sex and age), immunohistochemical expression of ESR2 was determined in 445 cases of incident colorectal cancer. Unconditional logistic regression was used in case-case analyses to assess heterogeneity between risk associations according to ESR2 status and in case-control analyses to estimate associations separately for ESR2-negative and ESR2-positive tumors. For ESR2-positive tumors but not ESR2-negative tumors, colorectal cancer risk significantly decreased with duration of oral contraceptive use [per five-year increments OR ESR2-positive, 0.87, 95% confidence interval (CI), 0.77-0.99; OR ESR2-negative, 1.02, 95% CI, 0.91-1.15; Pheterogeneity = 0.07] and with duration of menopausal hormone therapy use (per five-year increments OR ESR2-positive, 0.84, 95% CI, 0.74-0.95; OR ESR2-negative, 0.94, 95% CI 0.84-1.05; Pheterogeneity = 0.06). Significant heterogeneity according to ESR2 expression was found for the association with current use of menopausal hormone therapy (<0.5 years ago; Pheterogeneity = 0.023) but not for associations with reproductive factors. In conclusion, our results suggest that hormone use decreases risk for ESR2-positive but not ESR2-negative colorectal cancer.

Quality indicators for colorectal cancer screening for colonoscopy

The growing importance of colonoscopy in the prevention of colorectal cancer has stimulated an effort to identify and track quality indicators for this procedure. Several factors have been identified so far which are readily measurable and in many cases have been associated with improved patient outcomes. There is also ample evidence of variations in performance of this procedure. As a result, gathering data about quality indicators may play a vital role in the process of continuous quality improvement. Quality indicators for colonoscopy in colorectal cancer prevention are described along with the evidence that supports their use in benchmarking, quality reporting, and continuous quality improvement.

Five-year risk of colorectal neoplasia after normal baseline colonoscopy in asymptomatic Chinese Mongolian over 50 years of age

BACKGROUND

After normal colonoscopy, the 5-year risk of colorectal neoplasia is sufficiently low for asymptomatic people over 50 years of age. In China, the incidence of colorectal carcinoma of Mongolian people is higher than that of Han people. The aim of this study was to assess the 5-year risk of colorectal neoplasia after normal colonoscopy in asymptomatic Chinese Mongolian population.

PATIENTS AND METHODS

A cohort of asymptomatic Chinese Mongolian people (≥50 years old) were recruited and followed up with colonoscopy 5 years after colonoscopy. Baseline colonoscopy and follow-up colonoscopy findings were categorized based on the most advanced lesions: no adenoma, nonadvanced adenoma, and advanced adenoma. Five-year risk of colorectal neoplasia in these people was assessed according to the rates of no baseline adenoma and advanced adenoma at the end of 5 years.

RESULTS

A total of 480 of the 538 recruited people underwent follow-up colonoscopy at the end of 5 years. In people with no baseline adenoma, 27.3 % (82/301) was found to have any adenoma, and 1.7 % had advanced adenoma at follow-up colonoscopy. The risk of an advanced adenoma did not differ significantly between people with no adenoma at baseline and those with nonadvanced adenoma (relative risk (RR), 1.06; 95 % confidence interval (CI), 0.19-6.07). Advanced adenoma at baseline colonoscopy was the independent risk factor for advanced adenoma recurrence, compared with no adenoma at baseline (RR, 8.25; 95 % CI, 1.90-35.77).

CONCLUSION

The risk of advanced adenoma is low 5 years after the normal baseline colonoscopy, even in asymptomatic Chinese Mongolian population over 50 years of age.

Rescreening of persons with a negative colonoscopy result: results from a microsimulation model

BACKGROUND

Persons with a negative result on screening colonoscopy are recommended to repeat the procedure in 10 years.

OBJECTIVE

To assess the effectiveness and costs of colonoscopy versus other rescreening strategies after an initial negative colonoscopy result.

DESIGN

Microsimulation model.

DATA SOURCES

Literature and data from the Surveillance, Epidemiology, and End Results program.

TARGET POPULATION

Persons aged 50 years who had no adenomas or cancer detected on screening colonoscopy.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTION

No further screening or rescreening starting at age 60 years with colonoscopy every 10 years, annual highly sensitive guaiac fecal occult blood testing (HSFOBT), annual fecal immunochemical testing (FIT), or computed tomographic colonography (CTC) every 5 years.

OUTCOME MEASURES

Lifetime cases of colorectal cancer, life expectancy, and lifetime costs per 1000 persons, assuming either perfect or imperfect adherence.

RESULTS OF BASE-CASE ANALYSIS

Rescreening with any method substantially reduced the risk for colorectal cancer compared with no further screening (range, 7.7 to 12.6 lifetime cases per 1000 persons [perfect adherence] and 17.7 to 20.9 lifetime cases per 1000 persons [imperfect adherence] vs. 31.3 lifetime cases per 1000 persons with no further screening). In both adherence scenarios, the differences in life-years across rescreening strategies were small (range, 30 893 to 30 902 life-years per 1000 persons [perfect adherence] vs. 30 865 to 30 869 life-years per 1000 persons [imperfect adherence]). Rescreening with HSFOBT, FIT, or CTC had fewer complications and was less costly than continuing colonoscopy.

RESULTS OF SENSITIVITY ANALYSIS

Results were sensitive to test-specific adherence rates.

LIMITATION

Data on adherence to rescreening were limited.

CONCLUSION

Compared with the currently recommended strategy of continuing colonoscopy every 10 years after an initial negative examination, rescreening at age 60 years with annual HSFOBT, annual FIT, or CTC every 5 years provides approximately the same benefit in life-years with fewer complications at a lower cost. Therefore, it is reasonable to use other methods to rescreen persons with negative colonoscopy results.

PRIMARY FUNDING SOURCE

National Cancer Institute.

How should individuals with a false-positive fecal occult blood test for colorectal cancer be managed? A decision analysis

Several industrialized nations recommend fecal occult blood testing (FOBT) to screen for colorectal cancer (CRC), but corresponding screening guidelines do not specify how individuals with a prior false-positive FOBT result (fpFOBT) should be managed in terms of subsequent CRC screening. Accordingly, we conducted a decision analysis to compare different strategies for managing such individuals. We used a previously developed CRC microsimulation model, SimCRC, to calculate life-years and the lifetime number of colonoscopies (as a measure of required resources) for a cohort of 50-year-olds to whom FOBT-based CRC screening is offered annually from 50 to 75 years. We compared three management strategies for individuals with a prior fpFOBT: (i) resume screening in 10 years with 10-yearly colonoscopy (SwitchCol_long); (ii) resume screening in 1 year with annual FOBT (ContinueFOBT_Short) and (iii) resume screening in 10 years (i.e., the recommended interval following a negative colonoscopy) with annual FOBT (ContinueFOBT_long). We performed sensitivity analyses on various parameters and assumptions. When using different management strategies for individuals with a prior fpFOBT, the variation in the number of life-years gained relative to no screening was <2%, whereas the variation in the lifetime number of colonoscopies was 23% (percentages are calculated as the maximum difference across strategies divided by the lowest number across strategies). The ContinueFOBT_long strategy showed the lowest lifetime number of colonoscopies per life-year gained even when key assumptions were varied. In conclusion, the ContinueFOBT_long strategy was advantageous regarding both clinical benefit and required resources. Specifying an appropriate management strategy for individuals with a prior fpFOBT may substantially reduce required resources within a FOBT-based CRC screening program without limiting its effectiveness.

Association between colonoscopy and colorectal cancer mortality in a US cohort according to site of cancer and colonoscopist specialty

PURPOSE

We designed this study to evaluate the association of colonoscopy with colorectal cancer (CRC) death in the United States by site of CRC and endoscopist specialty.

METHODS

We designed a case-control study using Surveillance, Epidemiology, and End Results (SEER)-Medicare data. We identified patients (cases) diagnosed with CRC age 70 to 89 years from January 1998 through December 2002 who died as a result of CRC by 2007. We selected three matched controls without cancer for each case. Controls were assigned a referent date (date of diagnosis of the case). Colonoscopy performed from January 1991 through 6 months before the diagnosis/referent date was our primary exposure. We compared exposure to colonoscopy in cases and controls by using conditional logistic regression controlling for covariates, stratified by site of CRC. We determined endoscopist specialty by linkage to the American Medical Association (AMA) Masterfile. We assessed whether the association between colonoscopy and CRC death varied with endoscopist specialty.

RESULTS

We identified 9,458 cases (3,963 proximal [41.9%], 4,685 distal [49.5%], and 810 unknown site [8.6%]) and 27,641 controls. In all, 11.3% of cases and 23.7% of controls underwent colonoscopy more than 6 months before diagnosis. Compared with controls, cases were less likely to have undergone colonoscopy (odds ratio [OR], 0.40; 95% CI, 0.37 to 0.43); the association was stronger for distal (OR, 0.24; 95% CI, 0.21 to 0.27) than proximal (OR, 0.58; 95% CI, 0.53 to 0.64) CRC. The strength of the association varied with endoscopist specialty.

CONCLUSION

Colonoscopy is associated with a reduced risk of death from CRC, with the association considerably and consistently stronger for distal versus proximal CRC. The overall association was strongest if colonoscopy was performed by a gastroenterologist.

False-positive results from colorectal cancer screening in Catalonia (Spain), 2000-2010

OBJECTIVE

To identify factors associated with a false-positive result in a population-based colorectal cancer (CRC) screening programme with the faecal occult blood test (FOBT) in Catalonia between 2000 and 2010.

METHODS

The study population consisted of participants of the Catalan CRC screening programme with a positive FOBT who underwent a colonoscopy for diagnostic confirmation from 2000 to 2010. A false-positive result was defined as having a positive test but detecting no high-risk adenoma or cancer in the follow-up colonoscopy. Multivariate logistic regression models were performed to identify sociodemographic and screening variables related to false-positive results. Adjusted odds ratios (OR) and their 95% confidence intervals (CI) were estimated.

RESULTS

Over the screening period, 1074 (1.7%) of the 63,332 screening tests had a positive result in the Catalan CRC screening programme. The false-positive proportion was 55.2% (n = 546). Women were more likely to have a positive FOBT in the absence of CRC neoplasia than men (adjusted OR = 2.91; 95% CI: 2.22-3.28). During the first prevalence round, the proportion of false-positive results was higher than in subsequent rounds (69.5% vs. 48.9%; P < 0.05). Re-screening and having a bleeding pathology such as haemorrhoids or anal fissures were also associated with a false-positive result.

CONCLUSION

The proportion of false-positive results and the associated risks should be estimated to provide an eligible population with more reliable information on the adverse effects of screening.

Does CT colonography have a role for population-based colorectal cancer screening?

Colorectal cancer (CRC) is the second most common cancer and second most common cause of cancer-related deaths in Europe. CRC screening has been proven to reduce disease-specific mortality and several European countries employ national screening programmes. These almost exclusively rely on stool tests, with endoscopy used as an adjunct in some countries. Computed tomographic colonography (CTC) is a potential screening test, with an estimated sensitivity of 88 % for advanced neoplasia ≥10 mm. Recent randomised studies have shown that CTC and colonoscopy have similar yields of advanced neoplasia per screened invitee, indicating that CTC is potentially viable as a primary screening test. However, the evidence is not fully elaborated. It is unclear whether CTC screening is cost-effective and the impact of extracolonic findings, both medical and economic, remains unknown. Furthermore, the effect of CTC screening on CRC-related mortality is unknown, as it is also unknown for colonoscopy. It is plausible that both techniques could lead to decreased mortality, as for sigmoidoscopy and gFOBT. Although radiation exposure is a drawback, this disadvantage may be over-emphasised. In conclusion, the detection characteristics and acceptability of CTC suggest it is a viable screening investigation. Implementation will depend on detection of extracolonic disease and health-economic impact. Key Points • Meta-analysis of CT colonographic screening showed high sensitivity for advanced neoplasia ≥10mm. • CTC, colonoscopy and sigmoidoscopy screening all have similar yields for advanced neoplasia. • Good quality information regarding the cost-effectiveness of CTC screening is lacking. • There is little good quality data regarding the impact of extracolonic findings. • CTC triage is not clinically effective in first round gFOBT/FIT positives.

Comparison and combination of blood-based inflammatory markers with faecal occult blood tests for non-invasive colorectal cancer screening

Background:

Faecal occult blood tests (FOBTs) are widely used for colorectal cancer (CRC) screening. Blood-based inflammatory markers have been suggested as alternative or supplementary non-invasive CRC screening tests.

Methods:

Among 179 CRC patients, 193 people with advanced adenoma and 225 people free of neoplasm, C-reactive protein (CRP), serum CD26 (sCD26), complement C3a anaphylatoxin and tissue inhibitor of metalloproteinases 1 (TIMP-1) levels in blood were measured by ELISA tests, and an immunochemical FOBT (iFOBT) and a guaiac-based FOBT were performed. Receiver operating characteristic curves were constructed and the areas under the curves (AUCs) were compared.

Results:

The blood levels of CRP, sCD26 and TIMP-1 showed statistically significant differences between CRC patients and neoplasm-free participants, and levels of TIMP-1 were furthermore significantly elevated in advanced adenoma patients. For the four inflammatory markers, AUCs ranged from 0.52 to 0.62 for CRC detection and from 0.50 to 0.58 for advanced adenomas detection, compared with AUCs of 0.90 and 0.68 for the iFOBT. At 97% specificity, blood markers showed much lower sensitivities than FOBTs. Combining inflammatory markers with the iFOBT increased the AUC for advanced adenomas.

Conclusion:

These blood-based markers do not seem to be an alternative to FOBT-based CRC screening. The potential use of these and other blood-based tests in combination with iFOBT might deserve further attention.

Adenoma incidence decreases under the effect of polypectomy

AIM: To investigate whether, under the influence of polypectomy, the incidence of adenoma decreases with age.

METHODS: Consecutive patients with colonic adenomas identified at index colonoscopy were retrospectively selected if they had undergone three or more complete colonoscopies, at least 24 mo apart. Patients who had any first-degree relative with colorectal cancer were excluded. Data regarding number of adenomas at each colonoscopy, their location, size and histological classification were recorded. The monthly incidence density of adenomas after the index examination was estimated for the study population, by using the person-years method. Baseline adenomas were excluded from incidence calculations but their characteristics were correlated with recurrence at follow-up, using the χ² test.

RESULTS: One hundred and fifty-six patients were included (109 male, mean age at index colonoscopy 56.8 ± 10.3 years), with follow-up that ranged from 48 to 232 mo. No significant correlations were observed between the number, the presence of villous component, or the size of adenomas at index colonoscopy and the presence of adenomas at subsequent colonoscopies (P = 0.49, 0.12 and 0.78, respectively). The incidence of colonic adenomas was observed to decay from 1.4% person-months at the beginning of the study to values close to 0%, at 12 years after index colonoscopy.

CONCLUSION: Our results suggest the sporadic formation of adenomas occurs within a discrete period and that, when these adenomas are removed, all neoplasia-prone clones may be extinguished.

A comprehensive investigation on common polymorphisms in the MDR1/ABCB1 transporter gene and susceptibility to colorectal cancer

ATP Binding Cassette B1 (ABCB1) is a transporter with a broad substrate specificity involved in the elimination of several carcinogens from the gut. Several polymorphic variants within the ABCB1 gene have been reported as modulators of ABCB1-mediated transport. We investigated the impact of ABCB1 genetic variants on colorectal cancer (CRC) risk. A hybrid tagging/functional approach was performed to select 28 single nucleotide polymorphisms (SNPs) that were genotyped in 1,321 Czech subjects, 699 CRC cases and 622 controls. In addition, six potentially functional SNPs were genotyped in 3,662 German subjects, 1,809 cases and 1,853 controls from the DACHS study. We found that three functional SNPs (rs1202168, rs1045642 and rs868755) were associated with CRC risk in the German population. Carriers of the rs1202168_T and rs868755_T alleles had an increased risk for CRC (P(trend) = 0.016 and 0.029, respectively), while individuals bearing the rs1045642_C allele showed a decreased risk of CRC (P(trend) = 0.022). We sought to replicate the most significant results in an independent case-control study of 3,803 subjects, 2,169 cases and 1,634 controls carried out in the North of Germany. None of the SNPs tested were significantly associated with CRC risk in the replication study. In conclusion, in this study of about 8,800 individuals we show that ABCB1 gene polymorphisms play at best a minor role in the susceptibility to CRC.

Helicobacter pylori infection and colorectal cancer risk: evidence from a large population-based case-control study in Germany

Evidence concerning the role of Helicobacter pylori infection in the development of colorectal cancer remains controversial. The authors assessed the association of H. pylori seroprevalence with risk of colorectal cancer in a large population-based case-control study from Germany in 2003-2007. Serum antibodies to H. pylori in general and the cytotoxin-associated gene A protein (CagA) were measured in 1,712 incident colorectal cancer cases and 1,669 controls. The association between H. pylori seroprevalence and colorectal cancer risk was estimated by logistic regression, with adjustment for potential confounders and stratification by age group, sex, anatomic subsites, and cancer stage. Overall, H. pylori seroprevalence was higher in cases (46.1%) than in controls (40.1%), resulting in an age- and sex-adjusted odds ratio of 1.30 (95% confidence interval (CI): 1.14, 1.50). Adjustment for established colorectal cancer risk factors decreased the odds ratio to 1.26 (95% CI: 1.09, 1.47), with a further reduction to 1.18 (95% CI: 1.01, 1.38) after additional adjustment for previous colorectal endoscopy. Stratified analyses showed risk elevation to be essentially confined to left-sided colorectal cancer, with an odds ratio of 1.22 (95% CI: 1.02, 1.45), suggesting that H. pylori infection may be associated with a small yet relevant risk increase in the left colorectum.

A novel pit pattern identifies the precursor of colorectal cancer derived from sessile serrated adenoma

OBJECTIVES

Sessile serrated adenomas (SSAs) are known to be precursors of sporadic colorectal cancers (CRCs) with microsatellite instability (MSI), and to be tightly associated with BRAF mutation and the CpG island methylator phenotype (CIMP). Consequently, colonoscopic identification of SSAs has important implications for preventing CRCs, but accurate endoscopic diagnosis is often difficult. Our aim was to clarify which endoscopic findings are specific to SSAs.

METHODS

The morphological, histological and molecular features of 261 specimens from 226 colorectal tumors were analyzed. Surface microstructures were analyzed using magnifying endoscopy. Mutation in BRAF and KRAS was examined by pyrosequencing. Methylation of p16, IGFBP7, MLH1 and MINT1, -2, -12 and -31 was analyzed using bisulfite pyrosequencing.

RESULTS

Through retrospective analysis of a training set (n=145), we identified a novel surface microstructure, the Type II open-shape pit pattern (Type II-O), which was specific to SSAs with BRAF mutation and CIMP. Subsequent prospective analysis of an independent validation set (n=116) confirmed that the Type II-O pattern is highly predictive of SSAs (sensitivity, 65.5%; specificity, 97.3%). BRAF mutation and CIMP occurred with significant frequency in Type II-O-positive serrated lesions. Progression of SSAs to more advanced lesions was associated with further accumulation of aberrant DNA methylation and additional morphological changes, including the Type III, IV and V pit patterns.

CONCLUSIONS

Our results suggest the Type II-O pit pattern is a useful hallmark of the premalignant stage of CRCs with MSI and CIMP, which could serve to improve the efficacy of colonoscopic surveillance.

Trends in colorectal cancer incidence rates in the United States by tumor location and stage, 1992-2008

BACKGROUND

Results from case-control studies outside the United States have been conflicted about the efficacy of colonoscopy for reducing cancer risk in the right colon. To contribute to this discourse from an alternative perspective, we analyzed high-quality surveillance data to report on recent trends in population-based colorectal cancer incidence rates by tumor location in the United States.

METHODS

Data from cancer registries in the Surveillance, Epidemiology, and End Results Program were analyzed to examine colorectal cancer incidence trends from 1992 through 2008 among individuals aged ≥ 50 years (n = 267,072). Joinpoint regression analysis was used to quantify annual percent change in age-standardized rates by tumor location and disease stage.

RESULTS

Incidence rates for right-sided colon tumors decreased annually by 2.6% (95% CI: 2.0-3.2) since 1999 in men and 2.3% (CI: 1.6-3.0) since 2000 in women, after remaining stable during the previous seven/eight years. Incidence rates for left-sided tumors were generally decreasing from 1992 to 2008 in both sexes. Beginning in 1999/2000, substantial, almost identical annual declines occurred for late-stage disease in both the right and left colon: 3.9% (CI: 3.1-4.8) and 4.2% (CI: 3.5-4.9), respectively, in men; and 3.3% (CI: 2.5-4.1) and 3.3% (CI: 2.8-3.8) in women.

CONCLUSION

Large declines in the incidence of right-sided colon tumors among individuals 50 years and older began around 2000.

IMPACT

Increased colonoscopy utilization during the past decade may have contributed to a reduction in risk for cancers in both the right and left colorectum in the United States.

Improving protection against proximal colon cancer by colonoscopy

Colonoscopy protection against proximal cancer can be achieved, but the level of protection has thus far been less than left colon protection. Improved proximal protection begins with effective right colon bowel preparation, best achieved by split dosing the preparation regimen. Cecal intubation in screening examinations should exceed 95%, and must be documented by photography. Examiners must be proficient in detection of subtle right colon lesions, including serrated lesions as well as flat and depressed adenomas. Effective examination should be demonstrated by meeting recommended targets for adenoma detection.

Assessing the impact of screening colonoscopy on mortality in the medicare population

BACKGROUND

Some have recommended against routine screening for colorectal cancer (CRC) among patients ≥75 years of age, while others have suggested that screening colonoscopy (SC) is less beneficial for women than men. We estimated the expected benefits (decreased mortality from CRC) and harms (SC-related mortality) of SC based on sex, age, and comorbidity.

OBJECTIVE

To stratify older patients according to expected benefits and harms of SC based on sex, age, and comorbidity.

DESIGN

Retrospective study using Medicare claims data.

PARTICIPANTS

Medicare beneficiaries 67-94 years old with and without CRC.

MAIN MEASURES

Life expectancy, CRC- and colonoscopy-attributable mortality rates across strata of sex, age, and comorbidity, pay-off time (i.e. the minimum time until benefits from SC exceeded harms), and life-years saved for every 100,000 SC.

KEY RESULTS

Increasing age and comorbidity were associated with lower CRC-attributable mortality. Due to shorter life expectancy and CRC-attributable mortality, the benefits associated with SC were substantially lower among patients with greater comorbidity. Among men aged 75-79 years with no comorbidity, the number of life-years saved was 459 per 100,000 SC, while men aged 67-69 with ≥3 comorbidities had 81 life-years saved per 100,000 SC. There was no evidence that SC was less effective in women. Among men and women 75-79 with no comorbidity, number of life-years saved was 459 and 509 per 100,000 SC, respectively; among patients with ≥3 comorbidities, there was no benefit for either men or women.

CONCLUSIONS

Although the effectiveness of SC was equivalent for men and women, there was substantial variation in SC effectiveness within age groups, arguing against screening recommendations based solely on age.

Sojourn time of preclinical colorectal cancer by sex and age: estimates from the German national screening colonoscopy database

The sojourn time of preclinical colorectal cancer is a critical parameter in modeling effectiveness and cost-effectiveness of colorectal cancer screening. For ethical reasons, it cannot be observed directly, and available estimates are based mostly on relatively small historic data sets that do not include differentiation by age and sex. The authors derived sex- and age-specific estimates (age groups: 55-59, 60-64, 65-69, 70-74, 75-79, and ≥80 years) of mean sojourn time, combining data from the German national screening colonoscopy registry (based on 1.88 million records) and data from population-based cancer registries (population base: 37.9 million people) for the years 2003-2006. Estimates of mean sojourn time were similar for both sexes and all age groups and ranged from 4.5 years (95% confidence interval: 4.1, 4.8) to 5.8 years (95% confidence interval: 5.3, 6.3) for the subgroups assessed. Sensitivity analyses indicated that mean sojourn time might be approximately 1.5 years longer if colorectal cancer prevalence in nonparticipants of screening colonoscopy is 20% lower than prevalence in participants or 1 year shorter if it exceeds the prevalence in participants by 20%. This study provides, for the first time, precise estimates of sojourn time by age and sex, and it suggests that sojourn times are remarkably consistent across age groups and in both sexes.

Predictors of colorectal cancer following a negative colonoscopy in the Medicare population

BACKGROUND

The incidence of colorectal cancer following a normal colonoscopy in the Medicare population is not known.

METHODS

A 5% national sample of Medicare enrollees from 1996 to 2005 was used to identify patients undergoing complete colonoscopy. A colonoscopy not associated with any procedure (e.g., biopsy, polypectomy or fulguration) was defined as a negative colonoscopy. Patients with history of inflammatory bowel disease, colorectal cancer or death within 12 months of colonoscopy were excluded. A multivariable model was constructed to evaluate the factors associated with a new diagnosis of colorectal cancer in the period from 12 to 120 months following the negative colonoscopy.

RESULTS

Among 200,857 patients (mean age 74 years, 61% female, 92% White) with a negative colonoscopy, the incidence of colorectal cancer was 1.8 per 1,000 person-years. The incidence rate for matched follow-up periods decreased from 2.0/1,000 person-years for patients undergoing colonoscopy during 1996-2000 to 1.2/1,000 person years during 2001-2005. Multivariate analysis revealed a significant regional variation in the incidence of colorectal cancer following a negative colonoscopy. The incidence was higher in patients >85 years, males and patients who underwent a negative colonoscopy by a non-gastroenterologist or endoscopist in the lowest volume quartile. On stratified analyses, endoscopist volume was a significant predictor for non-gastroenterologists only.

CONCLUSIONS

The specialty and experience of the endoscopist are significant predictors of the incidence rate of colorectal cancer in Medicare patients with a negative colonoscopy.

Progression of low-grade dysplasia in ulcerative colitis: effect of colonic location

BACKGROUND

Emerging evidence suggests that the biology of sporadic colorectal neoplasia may differ between the proximal and distal colon. Whether such a difference exists in colitis-associated colorectal neoplasia is unknown.

OBJECTIVE

To compare the rate of progression to advanced neoplasia (AN) between proximal and distal dysplasia in patients with ulcerative colitis (UC).

DESIGN

Retrospective cohort study.

SETTING

Tertiary medical center.

PATIENTS

From an institutional database of more than 700 patients with UC who underwent 2 or more surveillance colonoscopies between 1994 and 2006, we identified patients with extensive UC and low-grade dysplasia (LGD). Neoplasia proximal to the splenic flexure was considered proximal.

MAIN OUTCOME MEASUREMENT

Progression to AN, defined as high-grade dysplasia (HGD) or colorectal cancer (CRC).

RESULTS

Among 121 patients with LGD, all 7 who progressed to CRC and 6 of 8 who progressed to HGD had distal LGD initially. Subjects with distal LGD had a significantly shorter time to progression than those with proximal LGD (P = .019); 5-year AN-free survivals for distal and proximal LGD were 75 ± 7% and 95 ± 3%, respectively (hazard ratio [HR] 5.0; 95% CI, 1.1-22.0). Additionally, flat LGD was significantly more likely to progress than raised LGD on univariate testing (HR 3.6; 95% CI, 1.3-10.1). Neither morphology nor sidedness remained significant in multivariable testing, although there was little change in the HRs (HR 2.4; 95% CI, 0.8-7.1 for morphology; HR 3.5; 95% CI, 0.7-16.8 for sidedness) in proportional hazards modeling.

LIMITATIONS

Nonrandomized, retrospective trial and low incidence of AN.

CONCLUSIONS

In patients with long-standing, extensive UC, distal LGD is more common and progresses more rapidly to AN than proximal LGD.

Anatomic classification of the endoscopic appearance of the normal appendiceal orifice: a novel tool for recognition and documentation of cecal intubation

Complete colonoscopy for cancer screening requires cecal intubation. Failure to reach and examine the cecum may result in missed right colon pathology. We developed and validated a novel classification scheme for the endoscopic appearance of the normal appendiceal orifice (AO). We analyzed 1,456 AO images and grouped them into four categories based on distinguishing features: "diverticuloid," "umbilicoid," "crescent," and "linear." An expert panel classified the images and modified these categories, combining crescent and linear categories into "curvilinear." A 100-image subset was classified twice by a validation cohort consisting of gastroenterology faculty and fellows. Inter-observer agreement among the expert panel, and intra- and inter-observer agreement among the validation cohort were analyzed using Fleiss' kappa statistic. The distribution of AO images was 67% curvilinear, 19% umbilicoid, and 10% diverticuloid; 85 images (4%) were not classifiable. There was substantial inter-observer agreement among the expert panel (κ, 0.72). Inter-observer agreement among the validation cohort was moderate (κ, 0.53 and 0.55 for the first and second viewing, respectively). Intra-observer κ values among the validation cohort were 0.69 for the overall classification, 0.65 for diverticuloid, 0.70 for umbilicoid, and 0.70 for curvilinear, indicating substantial agreement. This simple, validated classification scheme for the endoscopic appearance of the normal AO can be used both as a research and clinical tool to measure endoscopic quality, improve cecal examination, and document successful cecal intubation.

Long-term risk of colorectal cancer after negative colonoscopy

PURPOSE

Colonoscopy is thought to be a powerful and cost-effective tool to reduce colorectal cancer (CRC) incidence and mortality. Empirical evidence for overall and risk group-specific definition of screening intervals is sparse. We aimed to assess the risk of CRC according to time since negative colonoscopy, overall, and by sex, smoking, and family history of CRC, in a large population-based case-control study.

PATIENTS AND METHODS

In all, 1,945 patients with CRC and 2,399 population controls were recruited in 22 hospitals and through population registers in the Rhine-Neckar region of Germany from 2003 to 2007. Data on history of colonoscopy and important covariates were obtained by personal interviews and from medical records.

RESULTS

Compared with people who had never undergone colonoscopy, people with a previous negative colonoscopy had a strongly reduced risk of CRC. Adjusted odds ratios for time windows of 1 to 2, 3 to 4, 5 to 9, 10 to 19, and 20+ years after negative colonoscopy were 0.14 (95% CI, 0.10 to 0.20), 0.12 (95% CI, 0.08 to 0.19), 0.26 (95% CI, 0.18 to 0.39), 0.28 (95% CI, 0.17 to 0.45), and 0.40 (95% CI, 0.24 to 0.66), respectively. Low risks even beyond 10 years after negative colonoscopy were observed for both left- and right-sided CRC and in all risk groups assessed except current smokers, who had a risk similar to that of never smokers with no previous colonoscopy 10 or more years after a negative colonoscopy.

CONCLUSION

These results support suggestions that screening intervals for CRC screening by colonoscopy could be longer than the commonly recommended 10 years in most cases, perhaps even among men and people with a family history of CRC, but probably not among current smokers.

Clotting factor gene polymorphisms and colorectal cancer risk

PURPOSE

Increased coagulation has been associated with cancer onset and progression. Mainly small studies have addressed the association between clotting factor gene polymorphisms and the onset of colorectal cancer. We examined the association between six well-known clotting factor gene polymorphisms and colorectal cancer risk in a large case-control study.

PATIENTS AND METHODS

Factor V Leiden (rs6025), prothrombin G20210A (rs1799963), PAI-1 4G/5G (rs1799889), MTHFR 677C>T (rs1801133), fibrinogen gamma 10034C>T (rs2066865), and factor XIII Val34Leu (rs5985) were genotyped in 1,801 patients with colorectal cancer and 1,853 healthy controls from a large German population-based study. The risk of colorectal cancer associated with gene variants was determined by calculating odds ratios (ORs) and their 95% CIs using logistic regression.

RESULTS

Homozygous carriers of the prothrombotic factor V Leiden polymorphism showed a 5.8-fold increased risk (95% CI, 1.69 to 19.72) for colorectal cancer compared with noncarriers. A 30% reduced risk was found for heterozygous carriers of factor V Leiden (OR = 0.68; 95% CI, 0.52 to 0.90) and prothrombin G20210A (OR = 0.69; 95% CI, 0.49 to 0.96), implying an advantage for slightly increased thrombin generation. Carriers of the antithrombotic factor XIII Val34Leu polymorphism showed a 15% reduced risk of developing colorectal cancer (OR = 0.85; 95% CI, 0.74 to 0.97) compared with noncarriers. Our results did not support an effect of PAI-1 4G/5G, MTHFR 677C>T, and fibrinogen gamma 10034C>T on colorectal cancer risk.

CONCLUSION

Our results support a role of clotting factor polymorphisms and thereby the coagulation system in the risk of colorectal cancer.

Association of hydroxyprostaglandin dehydrogenase 15-(NAD) (HPGD) variants and colorectal cancer risk

A recent study examined associations of tagging single nucleotide polymorphisms (tagSNPs) in 43 fatty acid metabolism-related genes and risk of colorectal cancer (CRC), showing rs8752, rs2612656 and a haplotype [comprising both of the single nucleotide polymorphisms (SNPs)] in the hydroxyprostaglandin dehydrogenase 15-(NAD) (HPGD) gene to be positively associated with CRC risk. In the present study, we attempted to replicate these single marker and haplotype associations, using 1795 CRC cases and 1805 controls from the German Darmkrebs: Chancen der Verhütung durch Screening study (DACHS). In addition to rs8752 and rs2612656, HPGD tagSNPs rs9312555, rs17360144 and rs7349744 were genotyped for haplotype analyses. Except for a marginally significant inverse association of HPGD rs8752 with CRC risk [odds ratio (OR) = 0.85; 95% confidence interval (CI) = 0.74, 0.98; P = 0.03], none of the analyzed tagSNPs showed any association with CRC. Subset analyses for colon and rectal cancers yielded similar, yet non-significant risk estimates at all five loci. Also, none of the haplotypes was found to be associated with CRC, colon or rectal cancers. However, rs8752 was significantly associated with a decreased risk of CRC among individuals with a body mass index < 30 (OR = 0.82, 95% CI = 0.70, 0.95, P = 0.01) as well as among smokers (OR = 0.74, 95% CI = 0.61, 0.90, P = 0.003). Yet, our data do not support the previously reported associations of HPGD tagSNPs and risk of CRC.

Estimated long-term effects of the initial 6 years of the German screening colonoscopy program

BACKGROUND

Colorectal cancer is the most common cancer in Germany. Screening colonoscopies have been offered as a primary screening tool in Germany since the end of 2002.

OBJECTIVE

To estimate the numbers of clinically manifest colorectal cancers prevented by detection and removal of advanced adenomas in the initial 6 years of the program.

DESIGN

Markov model with single-year transitions.

SETTING

German screening colonoscopy program.

PATIENTS

Participants in the screening colonoscopy program from 2003 to 2008.

INTERVENTIONS

Screening colonoscopy with the removal of advanced colorectal neoplasms.

MAIN OUTCOME MEASUREMENTS

The expected numbers of incident colorectal cancers prevented by detection and removal of advanced adenomas.

RESULTS

An estimated total number of 73,024 cases of colorectal cancer might have developed from the removed advanced adenomas and become clinically manifest between 55 and 84 years of age in the absence of screening colonoscopy. This number exceeds the number of colorectal cancers diagnosed in 2002 by 27%. Among prevented cancers, 8%, 43%, and 49% would have occurred at ages 55 to 64, 65 to 74, and 75 to 84 years (median age 74 years), respectively; 60% and 40% would have occurred among men and women, respectively; and 22%, 32%, 25%, and 20% would have occurred within 1 to 5, 6 to 10, 11 to 15, and 16 to 30 years, respectively, after colonoscopy (median 10 years).

LIMITATIONS

Diagnoses of advanced adenomas are based on records from a large number of endoscopists and pathology laboratories.

CONCLUSIONS

Despite relatively low screening participation, the German screening colonoscopy program is expected to make a major contribution to the prevention of colorectal cancer, even though most of the impact will only be seen in the longer run.

Eight years of colonoscopic bowel cancer screening in Germany: initial findings and projections

BACKGROUND

Screening colonoscopy has been offered in Germany since the end of 2002. Our aim was to estimate numbers of colorectal cancers prevented or detected early by screening colonoscopy in 2003-2010.

METHODS

Participation rates and prevalences of advanced adenomas and colorectal cancers at screening colonoscopy in 2003-2008 were obtained from the national screening colonoscopy database by age, sex and calendar year. For 2009 and 2010, levels were assumed to remain at those observed in 2008. These data were combined in Markov models with population figures and estimates of transition rates from advanced adenomas to preclinical colorectal cancer and from preclinical cancer to clinically manifest cancer, accounting for total mortality.

RESULTS

An estimated total number of 98 734 cases of colorectal cancer at ages 55-84 years are expected to have been prevented in Germany by removal of advanced adenomas by the end of 2010. These cancers might have become clinically manifest a median time period of 10 years after screening colonoscopy. Another 47 168 cases are expected to have been detected early at screening colonoscopy, often in a curable stage.

CONCLUSION

Despite limited participation, the German screening colonoscopy program makes a major contribution to prevention and early detection of colorectal cancer.

Strategies for colon cancer prevention

Colorectal cancer (CRC) is common and is associated with a considerable mortality. Morbidity and thereby mortality can be reduced by using different prevention strategies such as lifestyle interventions and chemoprevention. Endoscopic surveillance of high-risk individuals and population-based endoscopic screening of average-risk individuals enables detection and removal of premalignant lesions (adenomas) as well as presymptomatic detection of cancer. Implementation of cancer detection tests such as fecal occult blood tests (FOBTs) is another strategy to reduce cancer mortality by early detection of CRC. Personalized management, based on estimates of the individual risk using information concerning environmental factors, lifestyle, family history, personality, social background and phenotype in combination with a variety of biomarkers such as genotype, will become more important as a strategy to optimize CRC prevention in the future.

The dimensions of the CRC problem

Colorectal cancer is a significant health problem, the importance of which will increase substantially in the coming years, both in more, as well as in less developed regions of the world. The present paper describes the dimensions of the problem from an epidemiologic viewpoint as well as from the perspective of policy makers and professionals seeking to control the disease. Currently, colorectal cancer is the third most common cancer and the fourth most common cause of cancer deaths worldwide, with 1.2 million estimated cases and 609,000 estimated deaths in 2008. Based on demographic trends, the annual incidence is expected to increase by nearly 80% to 2.2 million cases over the next two decades and most of this increase will occur in the less developed regions of the world (62%). These regions are ill equipped to deal with the rapidly increasing demand for cancer treatment resulting from population growth and higher life expectancy. Concerted efforts to control colorectal cancer are therefore of great importance worldwide. They will require allocation of additional resources and should be based on an appropriate balance between prevention, diagnosis and treatment.

An evidence-based microsimulation model for colorectal cancer: validation and application

BACKGROUND

The Colorectal Cancer Simulated Population model for Incidence and Natural history (CRC-SPIN) is a new microsimulation model for the natural history of colorectal cancer that can be used for comparative effectiveness studies of colorectal cancer screening modalities.

METHODS

CRC-SPIN simulates individual event histories associated with colorectal cancer, based on the adenoma-carcinoma sequence: adenoma initiation and growth, development of preclinical invasive colorectal cancer, development of clinically detectable colorectal cancer, death from colorectal cancer, and death from other causes. We present the CRC-SPIN structure and parameters, data used for model calibration, and model validation. We also provide basic model outputs to further describe CRC-SPIN, including annual transition probabilities between various disease states and dwell times. We conclude with a simple application that predicts the impact of a one-time colonoscopy at age 50 on the incidence of colorectal cancer assuming three different operating characteristics for colonoscopy.

RESULTS

CRC-SPIN provides good prediction of both the calibration and the validation data. Using CRC-SPIN, we predict that a one-time colonoscopy greatly reduces colorectal cancer incidence over the subsequent 35 years.

CONCLUSIONS

CRC-SPIN is a valuable new tool for combining expert opinion with observational and experimental results to predict the comparative effectiveness of alternative colorectal cancer screening modalities.

IMPACT

Microsimulation models such as CRC-SPIN can serve as a bridge between screening and treatment studies and health policy decisions by predicting the comparative effectiveness of different interventions. As such, it is critical to publish model descriptions that provide insight into underlying assumptions along with validation studies showing model performance.

An evidence-based microsimulation model for colorectal cancer: validation and application

BACKGROUND

The Colorectal Cancer Simulated Population model for Incidence and Natural history (CRC-SPIN) is a new microsimulation model for the natural history of colorectal cancer that can be used for comparative effectiveness studies of colorectal cancer screening modalities.

METHODS

CRC-SPIN simulates individual event histories associated with colorectal cancer, based on the adenoma-carcinoma sequence: adenoma initiation and growth, development of preclinical invasive colorectal cancer, development of clinically detectable colorectal cancer, death from colorectal cancer, and death from other causes. We present the CRC-SPIN structure and parameters, data used for model calibration, and model validation. We also provide basic model outputs to further describe CRC-SPIN, including annual transition probabilities between various disease states and dwell times. We conclude with a simple application that predicts the impact of a one-time colonoscopy at age 50 on the incidence of colorectal cancer assuming three different operating characteristics for colonoscopy.

RESULTS

CRC-SPIN provides good prediction of both the calibration and the validation data. Using CRC-SPIN, we predict that a one-time colonoscopy greatly reduces colorectal cancer incidence over the subsequent 35 years.

CONCLUSIONS

CRC-SPIN is a valuable new tool for combining expert opinion with observational and experimental results to predict the comparative effectiveness of alternative colorectal cancer screening modalities.

IMPACT

Microsimulation models such as CRC-SPIN can serve as a bridge between screening and treatment studies and health policy decisions by predicting the comparative effectiveness of different interventions. As such, it is critical to publish model descriptions that provide insight into underlying assumptions along with validation studies showing model performance.

New endoscopy devices to improve population adherence to colorectal cancer prevention programs

Despite recent advances in medicine, colorectal cancer (CRC) remains one of the greatest hazards for public health worldwide and especially the industrialized world. It has been well documented with concrete data that regular screening colonoscopy aimed at early detection of precancerous polyps can help decrease the incidence of CRC. However, the adherence of the general population to such screening programs has been shown to be lower than that expected, thus allowing CRC to remain a major threat for public health. Various reasons have been suggested to explain the disappointing compliance of the population to CRC screening programs, some of them associated with colonoscopy per se, which is viewed by many people as an unpleasant examination. Governments, medical societies, individual gastroenterologists, as well as the medical industry are working in order to improve endoscopic devices and/or to improve standard colonoscopy. The aim is to improve the acceptance of the population for this method of CRC screening, by providing a painless and reliable examination of the colon. This review focuses on some of the latest improvements in this field.

Genome-wide association study for colorectal cancer identifies risk polymorphisms in German familial cases and implicates MAPK signalling pathways in disease susceptibility

Genetic susceptibility accounts for approximately 35% of all colorectal cancer (CRC). Ten common low-risk variants contributing to CRC risk have been identified through genome-wide association studies (GWASs). In our GWAS, 610 664 genotyped single-nucleotide polymorphisms (SNPs) passed the quality control filtering in 371 German familial CRC patients and 1263 controls, and replication studies were conducted in four additional case-control sets (4915 cases and 5607 controls). Known risk loci at 8q24.21 and 11q23 were confirmed, and a previously unreported association, rs12701937, located between the genes GLI3 (GLI family zinc finger 3) and INHBA (inhibin, beta A) [P = 1.1 x 10(-3), odds ratio (OR) 1.14, 95% confidence interval (CI) 1.05-1.23, dominant model in the combined cohort], was identified. The association was stronger in familial cases compared with unselected cases (P = 2.0 x 10(-4), OR 1.36, 95% CI 1.16-1.60, dominant model). Two other unreported SNPs, rs6038071, 40 kb upstream of CSNK2A1 (casein kinase 2, alpha 1 polypeptide) and an intronic marker in MYO3A (myosin IIIA), rs11014993, associated with CRC only in the familial CRC cases (P = 2.5 x 10(-3), recessive model, and P = 2.7 x 10(-4), dominant model). Three software tools successfully pointed to the overrepresentation of genes related to the mitogen-activated protein kinase (MAPK) signalling pathways among the 1340 most strongly associated markers from the GWAS (allelic P value < 10(-3)). The risk of CRC increased significantly with an increasing number of risk alleles in seven genes involved in MAPK signalling events (P(trend) = 2.2 x 10(-16), OR(per allele) = 1.34, 95% CI 1.11-1.61).

Relationship of non-polypoid colorectal neoplasms to quality of colonoscopy

Colonoscopy is a dominant modality for colorectal cancer prevention in average-risk patients aged 50 years and older. Non-polypoid colorectal neoplasms (NP-CRNs) are likely a significant contributing factor to interval colorectal cancers because they have a higher prevalence in Western populations than previously thought, are more difficult to detect visually with conventional colonoscopy, and are more likely to contain advanced histology than polypoid neoplasms, regardless of size. The accurate identification and complete removal of NP-CRNs is thus an integral part of high-quality colonoscopy, and a critical component of the ongoing efforts to make colorectal cancer screening programs widely available, effective, and accepted by patients. In this article, the authors examine the quality indicators for colonoscopy, present the reasons for interval cancers, and discuss the relation between NP-CRNs and quality colonoscopy.

Study protocol: population screening for colorectal cancer by colonoscopy or CT colonography: a randomized controlled trial

Background

Colorectal cancer (CRC) is the second most prevalent type of cancer in Europe. Early detection and removal of CRC or its precursor lesions by population screening can reduce mortality. Colonoscopy and computed tomography colonography (CT colonography) are highly accurate exams and screening options that examine the entire colon. The success of screening depends on the participation rate. We designed a randomized trial to compare the uptake, yield and costs of direct colonoscopy population screening, using either a telephone consultation or a consultation at the outpatient clinic, versus CT colonography first, with colonoscopy in CT colonography positives.

Methods and design

7,500 persons between 50 and 75 years will be randomly selected from the electronic database of the municipal administration registration and will receive an invitation to participate in either CT colonography (2,500 persons) or colonoscopy (5,000 persons) screening. Those invited for colonoscopy screening will be randomized to a prior consultation either by telephone or a visit at the outpatient clinic. All CT colonography invitees will have a prior consultation by telephone. Invitees are instructed to consult their general practitioner and not to participate in screening if they have symptoms suggestive for CRC. After providing informed consent, participants will be scheduled for the screening procedure. The primary outcome measure of this study is the participation rate. Secondary outcomes are the diagnostic yield, the expected and perceived burden of the screening test, level of informed choice and cost-effectiveness of both screening methods.

Discussion

This study will provide further evidence to enable decision making in population screening for colorectal cancer.

Trial registration

Dutch trial register: NTR1829

Single nucleotide polymorphisms in Wnt signaling and cell death pathway genes and susceptibility to colorectal cancer

It is well known that approximately 90% of colorectal cancer (CRC) cases originate from the constitutive activation of the canonical Wnt signaling pathway. There is increasing evidence that genetic variation both in Wnt and apoptotic pathway genes affects CRC susceptibility and progression. This population-based case-control study, including 1795 CRC cases and 1805 controls, investigates the association between common, putative functional polymorphisms in DNFA5, HIF1A, NDRG1, PYGO1, SFRP2, SFRP4, WISP1 and WISP3 genes and CRC risk. We found no evidence for an association between the selected allelic variants and risk of CRC. Subsite analyses, however, revealed a significant association of HIF1A c.*191T>C with rectal cancer risk [odds ratio (OR) = 1.25, 95% confidence interval (CI), 1.03-1.51, P = 0.03] comparing minor allele carriers with major allele homozygotes. In addition, homozygosity for the minor allele of SFRP4 P320T was significantly associated with rectal cancer risk (OR = 1.37, 95% CI, 1.06-1.79, P = 0.02) and early-stage CRC (OR = 1.33, 95% CI, 1.05-1.69, P = 0.02). This study does not support the hypothesis that Wnt signaling- and apoptosis-related polymorphisms contribute to CRC risk. However, our results provide evidence that CRC subsets may be affected. If confirmed, this knowledge may be used to assess individual susceptibility and to target potential measures of cancer prevention.

Predictors of colorectal cancer after negative colonoscopy: a population-based study

OBJECTIVES

A higher proportion of colorectal neoplasia among women occurs in the proximal colon, which might be more frequently missed by colonoscopy. There are no data on predictors of developing colorectal cancer (CRC) after a negative colonoscopy in usual clinical practice. We evaluated gender differences and predictors of CRC occurring after a negative colonoscopy.

METHODS

All individuals 40 years or older with negative colonoscopy were identified from Manitoba's provincial physicians' billing claims database. Individuals with less than 5 years of coverage by the provincial health plan, earlier CRC, inflammatory bowel disease, resective colorectal surgery, or lower gastrointestinal endoscopy were excluded. CRC risk after negative colonoscopy was compared to that in the general population by standardized incidence ratios. Cox regression analysis was performed to determine the independent predictors of CRC occurring after negative colonoscopy.

RESULTS

A total of 45,985 individuals (18,606 men; 27,379 women) were followed up for 229,090 person-years. After a negative colonoscopy, men had a 40-50% lower risk of CRC diagnosis through most of the follow-up time. Risk among women was similar to that of women in the general population in the first 3 years and then was 40-50% lower. Older subject age and performance of index colonoscopy by non-gastroenterologists were independent predictors for early/missed CRC (cancers occurring within 3 years of negative colonoscopy).

CONCLUSIONS

Women may have a higher rate of missed/early CRCs after negative colonoscopy. Predictors of missed/early CRCs after negative colonoscopy include older age and performance of index colonoscopy by a non-gastroenterologist.

Low risk of colorectal cancer and advanced adenomas more than 10 years after negative colonoscopy

BACKGROUND & AIMS

Screening colonoscopy is an effective method to reduce the incidence of and mortality from colorectal cancer (CRC). There is little empirical evidence available about the optimal interval for screening, making this a subject of debate. We associated the prevalence of advanced colorectal neoplasms with time since negative colonoscopies.

METHODS

In a study of participants in the German colonoscopy screening program, we determined the prevalence of colorectal neoplasias detected at screening colonoscopy among subjects who had undergone a previous colonoscopy without detection of polyps (negative colonoscopy). Data were compared with that from subjects who had not received colonoscopies.

RESULTS

No CRCs were detected in participants who had a previous negative colonoscopy an average of 11.9 years previously (n = 553), compared with the 8.4 CRC cases expected based on age- and gender-specific prevalences among participants who had not received a colonoscopy (n = 2701; standardized prevalence ratio [SPR] = 0.00; 95% confidence interval [CI]: 0.00-0.55). Prevalence of advanced adenoma was also much lower among subjects who had previous colonoscopies (SPR = 0.42; 95% CI: 0.25-0.68). Adjusted prevalence ratios (95% CIs) for detecting an advanced adenoma were 0.38 (95% CI: 0.16-0.90), 0.34 (95% CI: 0.15-0.74), 0.38 (95% CI: 0.16-0.90), and 0.53 (95% CI: 0.27-1.04) among participants with a negative colonoscopy conducted 1-5, 6-10, 11-15, and >16 years ago, respectively, compared to participants with no previous colonoscopy.

CONCLUSIONS

The low risk of CRC and advanced adenomas after a negative colonoscopy supports suggestions that screening intervals be extended to > or =10 years.

Protection from right- and left-sided colorectal neoplasms after colonoscopy: population-based study

BACKGROUND

Colonoscopy is used for early detection and prevention of colorectal cancer, but evidence on the magnitude of overall protection and protection according to anatomical site through colonoscopy performed in the community setting is sparse. We assessed whether receiving a colonoscopy in the preceding 10-year period, compared with no colonoscopy, was associated with prevalence of advanced colorectal neoplasms (defined as cancers or advanced adenomas) at various anatomical sites.

METHODS

A statewide cross-sectional study was conducted among 3287 participants in screening colonoscopy between May 1, 2005, and December 31, 2007, from the state of Saarland in Germany who were aged 55 years or older. Prevalence of advanced colorectal neoplasms was ascertained by screening colonoscopy and histopathologic examination of any polyps excised. Previous colonoscopy history was obtained by standardized questionnaire, and its association with prevalence of advanced colorectal neoplasms was estimated, after adjustment for potential confounding factors by log-binomial regression.

RESULTS

Advanced colorectal neoplasms were detected in 308 (11.4%) of the 2701 participants with no previous colonoscopy compared with 36 (6.1%) of the 586 participants who had undergone colonoscopy within the preceding 10 years. After adjustment, overall and site-specific adjusted prevalence ratios for previous colonoscopy in the previous 10-year period were as follows: overall, 0.52 (95% confidence interval [CI] = 0.37 to 0.73); cecum and ascending colon, 0.99 (95% CI = 0.50 to 1.97); hepatic flexure and transverse colon, 1.21 (95% CI = 0.60 to 2.42); right-sided colon combined (cecum to transverse colon), 1.05 (95% CI = 0.63 to 1.76); splenic flexure and descending colon, 0.36 (95% CI = 0.16 to 0.82); sigmoid colon, 0.29 (95% CI = 0.16 to 0.53); rectum, 0.07 (95% CI = 0.02 to 0.40); left colon and rectum combined (splenic flexure to rectum, referred to as left-sided elsewhere), 0.33 (95% CI = 0.21 to 0.53).

CONCLUSION

Prevalence of left-sided advanced colorectal neoplasms, but not right-sided advanced neoplasms, was strongly reduced within a 10-year period after colonoscopy, even in the community setting.

Colorectal cancer and polymorphisms in DNA repair genes WRN, RMI1 and BLM

RecQ helicase family members are involved in multiple DNA repair pathways, protecting the genome from incorrect recombination during mitosis and maintaining its stability. Deficiencies in genes encoding the RecQ helicases WRN and BLM lead to rare autosomal recessive diseases, Werner and Bloom syndromes, which have been implicated in early onset of aging, and predisposition to various types of cancer. We investigated associations of WRN, BLM and BLM-associated protein (BLAP75/RMI1) gene polymorphisms and risk of colorectal cancer (CRC), genotyping WRN V114I (rs2230009), WRN L1074F (rs2725362), WRN C1367R (rs1346044), RMI1 S455N (rs1982151) and BLM P868L (rs11852361). A large population-based case-control study, including 1795 CRC cases and 1805 controls, found no evidence for an association between the selected allelic variants in DNA repair-related genes and CRC risk. However, we detected a significant association of BLM P868L with an increased rectal cancer risk (odds ratio = 1.29, 95% confidence interval 1.02-1.64 and P = 0.04), suggesting a potential cancer-site specificity. This is the first study to analyze the associations between polymorphisms in WRN, BLM and RMI1 and CRC risk. Although none of them showed a significant association with CRC, the association of BLM P868L with rectal cancer risk requires further investigation.

Second look colonoscopy: indication and requirements

BACKGROUND

There are circumstances when a colonoscopy should be repeated after a short interval following the first endoscopic procedure which has not completely fulfilled its objective.

REVIEW OF THE LITERATURE

A second look colonoscopy is proposed when there remains a doubt about missed neoplastic lesions, either because the intestinal preparation was poor or because the video-endoscope did not achieved a complete course in the colon. The second look colonoscopy is also proposed at a short interval when it is suspected that the endoscopic removal of a single or of multiple neoplastic lesions was incomplete and that a complement of treatment is required. When the initial endoscopic procedure has completely fulfilled its objective, a second look colonoscopy can be proposed at longer intervals in surveillance programs. The intervals in surveillance after polypectomy are now adapted to the initial findings according to established guidelines. This also applies to the surveillance of incident focal cancer in patients suffering from a chronic inflammatory bowel disease.

CONCLUSION

Finally, in most developed countries, a priority is attributed to screening of colorectal cancer and focus is given on quality assurance of colonoscopy which is considered as the gold standard procedure in the secondary prevention of colorectal cancer.

American College of Gastroenterology guidelines for colorectal cancer screening 2009 [corrected]

This document is the first update of the American College of Gastroenterology (ACG) colorectal cancer (CRC) screening recommendations since 2000. The CRC screening tests are now grouped into cancer prevention tests and cancer detection tests. Colonoscopy every 10 years, beginning at age 50, remains the preferred CRC screening strategy. It is recognized that colonoscopy is not available in every clinical setting because of economic limitations. It is also realized that not all eligible persons are willing to undergo colonoscopy for screening purposes. In these cases, patients should be offered an alternative CRC prevention test (flexible sigmoidoscopy every 5-10 years, or a computed tomography (CT) colonography every 5 years) or a cancer detection test (fecal immunochemical test for blood, FIT).