Colorectal cancer risk factors in the detection of advanced adenoma and colorectal cancer

Several risk factors for colorectal cancer (CRC) have been identified. If individuals with risk factors are more likely to harbor cancer or it precursors screening programs should be targeted toward this population. We evaluated the predictive value of colorectal cancer risk factors for the detection of advanced colorectal adenoma in a population based CRC colonoscopy screening program. Data were collected in a multicenter trial conducted in the Netherlands, in which 6600 asymptomatic men and women between 50 and 75 years were randomly selected from a population registry. They were invited to undergo a screening colonoscopy. Based on a review of the literature CRC risk factors were selected. Information on risk factors was obtained from screening attendees through a questionnaire. For each CRC risk factor, we estimated its odds ratio (OR) relative to the presence of advanced neoplasia as detected at colonoscopy. Of the 1426 screening participants who underwent a colonoscopy, 1236 (86%) completed the risk questionnaire. 110 participants (8.9%) had advanced neoplasia. The following risk factors were significantly associated with advanced neoplasia detected by colonoscopy: age (OR: 1.06 per year; 95% CI: 1.03–1.10), calcium intake (OR: 0.99 per mg; 95% CI: 0.99–1.00), positive CRC family history (OR: 1.55 per first degree family member; 95%CI: 1.11–2.16) and smoking (OR: 1.75; 95%CI: 1.09–2.82). Elderly screening participants, participants with lower calcium intake, a CRC family history, and smokers are at increased risk of harboring detectable advanced colorectal neoplasia at screening colonoscopy.     

Risk of advanced colorectal neoplasia according to age and gender

Background

Colorectal cancer (CRC) is one of the leading causes of cancer related morbidity and death. Despite the fact that the mean age at diagnosis of CRC is lower in men, screening by colonoscopy or fecal occult blood test (FOBT) is initiated at same age in both genders. The prevalence of the common CRC precursor lesion, advanced adenoma, is well documented only in the screening population. The purpose of this study was to assess the risk of advanced adenoma at ages below screening age.

Methods and Findings

We analyzed data from a census of 625,918 outpatient colonoscopies performed in adults in Bavaria between 2006 and 2008. A logistic regression model to determine gender- and age-specific risk of advanced neoplasia was developed. Advanced neoplasia was found in 16,740 women (4.6%) and 22,684 men (8.6%). Male sex was associated with an overall increased risk of advanced neoplasia (odds ratio 1.95; 95% confidence interval, CI, 1.91 to 2.00). At any age and in any indication group, more colonoscopies were needed in women than in men to detect advanced adenoma or cancer. At age 75 14.8 (95% CI, 14.4–15.2) screening, 18.2 (95% CI, 17.7–18.7) diagnostic, and 7.9 (95% CI, 7.6–8.2) colonoscopies to follow up on a positive FOBT (FOBT colonoscopies) were needed to find advanced adenoma in women. At age 50 39.0 (95% CI, 38.0–40.0) diagnostic, and 16.3 (95% CI, 15.7–16.9) FOBT colonoscopies were needed. Comparable numbers were reached 20 and 10 years earlier in men than in women, respectively.

Conclusions

At any age and independent of the indication for colonoscopy, men are at higher risk of having advanced neoplasia diagnosed upon colonoscopy than women. This suggests that starting screening earlier in life in men than in women might result in a relevant increase in the detection of asymptomatic preneoplastic and neoplastic colonic lesions.     

Cost-Effectiveness of Colorectal Cancer Screening Protocols in Urban Chinese Populations

Colorectal cancer (CRC) takes a second and fourth position in the incidence and mortality lists respectively among all malignant tumors in urban populations in China. This study was designed to evaluate the cost-effectiveness of two different CRC screening protocols: faecal occult blood test (FOBT) alone, and FOBT plus a high-risk factor questionnaire (HRFQ) as the respective initial screens, followed by colonoscopy. We developed a Markov model to simulate the progression of a cohort of 100,000 average risk asymptomatic individuals moving through a defined series of states between the ages of 40 to 74 years. The parameters used for the modeling came from the CESP (Comparison and Evaluation of Screening Programs for Colorectal Cancer in Urban Communities in China) study and published literature. Eight CRC screening scenarios were tested in the Markov model. The cost-effectiveness of CRC screening under each scenario was measured by an incremental cost-effectiveness ratio (ICER) compared with a scenario without CRC screening. The study revealed that a combined use of FOBT and HRFQ is preferable in CRC screening programs as an initial screening instrument. Annual FOBT+HRFQ screening is recommended for those who have a negative initial result and those who have a positive result but have failed to continue to colonoscopic examination. Repeated colonoscopy (for those with a positive result in initial screening but a negative colonoscopy result) should be performed at a ten-year interval instead of one-year. Such a protocol would cost 7732 Yuan per life year saved, which is the most cost-effective option. In conclusion, the current Chinese Trial Version for CRC Screening Strategy should be revised in line with the most cost-effective protocol identified in this study.     

Trends and inequities in colorectal cancer screening participation in Ontario,Canada, 2005–2011

Background: Participation in screening tests for colorectal cancer (CRC) is generally low in Ontario, Canada. In addition, inequities in participation exist including lower participation among low-income individuals, males and individuals living in rural areas. In April 2008, Colon Cancer Check (CCC) program, the province-wide CRC screening program, was launched in Ontario. This study describes the trends and inequities in CRC screening participation three years before and three years after the CCC, and assesses the effect of the program on CRC screening participation, overall and among certain population groups. Methods: We used administrative data to identify cohorts of individuals eligible for CRC screening in fiscal years 2005–2011. We calculated the age-standardized percent of Fecal Occult Blood Test (FOBT) participation, large bowel endoscopy participation, and being ‘up-to-date’ with CRC screening tests. Results: From 2005 to 2011, FOBT participation increased from 7.6% to 14.8%, large bowel endoscopy participation from 3.4% to 5.7%, and ‘up-to-date’ with CRC screening from 27.2% to 41.3%. Before the launch of the CCC program, the quarterly increase in FOBT participation was 0.07% (p = 0.19), increased immediately after the launch (1.8%, p < 0.01), followed by a decline (?0.08%, p = 0.08), returning to its pre-program increase rate. We noted a significant decrease in FOBT participation every summer (?0.44%, p < 0.01). The CCC program had minimal effect on large bowel endoscopy participation. Before the launch of the CCC program, the quarterly increase in ‘up-to-date’ with CRC screening was 0.9% (p < 0.01), increased immediately after the launch (2.5%, p = 0.05), followed by a modest decline thereafter (?0.59%, p < 0.02). From 2005 to 2011, recent residents living in low-income neighborhoods were consistently and significantly less likely to have a FOBT and be ‘up-to-date’ with CRC screening than long-term residents living in high-income neighborhoods (2.9–4.5%; 14.7–17.3% respectively). Pre-CCC inequities in CRC participation persisted after the launch of the program. Conclusion: CRC testing was increasing in Ontario from 2005. An immediate increase in CRC testing, FOBT in particular, occurred after the launch of the CCC program, followed by a return to its pre-CCC increase rate thereafter. Future efforts are needed to improve screening participation and address inequities.     

Inter-Physician Variation in Follow-Up Colonoscopies after Screening Colonoscopy

Background and Aims

Surveillance is an integral part of the colorectal cancer (CRC) screening process. We aimed to investigate inter-physician variation in follow-up procedures after screening colonoscopy in an opportunistic CRC screening program.

Methods

A historical cohort study in the German statutory health insurance system was conducted. 55,301 individuals who underwent screening colonoscopy in 2006 in Bavaria, Germany, and who were not diagnosed with CRC were included. Utilization of follow-up colonoscopies performed by the same physician (328 physicians overall) within 3 years was ascertained. Mixed effects logistic regression modelling was used to assess the effect of physicians and other potential predictors (screening result, age group, and sex) on re-utilization of colonoscopy. Physicians were grouped into quintiles according to individual effects estimated in a preliminary model. Predicted probabilities of follow-up colonoscopy by screening result and physician group were calculated.

Results

The observed rate of follow-up colonoscopy was 6.2% (95% confidence interval: 5.9-6.4%), 18.6% (17.8-19.4%), and 37.0% (35.5-38.4%) after negative colonoscopy, low-risk adenoma and high-risk adenoma detection, respectively. All considered predictors were statistically significantly associated with follow-up colonoscopy. The predicted probabilities of follow-up colonoscopy ranged from 1.7% (1.4-2.0%) to 11.0% (10.2-11.7%), from 7.3% (6.2-8.5%) to 35.1% (32.6-37.7%), and from 17.9% (15.5-20.6%) to 56.9% (53.5-60.3%) in the 1^st quintile (lowest rates of follow-up) and 5^th quintile (highest rates of follow-up) of physicians after negative colonoscopy, low-risk adenoma and high-risk adenoma detection, respectively.

Conclusions

This study suggests substantial inter-physician variation in follow-up habits after screening colonoscopy. Interventions, including organizational changes in CRC screening should be considered to reduce this variation.     

Adherence to Physician Recommendations for Surveillance in Opportunistic Colorectal Cancer Screening: The Necessity of Organized Surveillance

Background

Limited evidence exists on the utilization of surveillance colonoscopy in colorectal cancer (CRC) screening programs. We assessed adherence to physician recommendations for surveillance in opportunistic CRC screening in Germany.

Methods

A follow-up study of screening colonoscopy participants in 2007-2009 in Saarland, Germany, was conducted using health insurance claims data. Utilization of additional colonoscopies through to 2011 was ascertained. Adherence to surveillance intervals of 3, 6, 12 and 36 months, defined as having had colonoscopy at 2.5 to 4, 5 to 8, 10.5 to 16 and 33 to 48 months, respectively (i.e., tolerating a delay of 33% of each interval) was assessed. Potential predictors of non-adherence were investigated using logistic regression analysis.

Results

A total of 20,058 screening colonoscopy participants were included in the study. Of those with recommended surveillance intervals of 3, 6, 12 and 36 months, 46.5% (95%-confidence interval [CI]: 37.3-55.7%), 38.5% (95%-CI: 29.6-47.3%), 25.4% (95%-CI: 21.2-29.6%) and 28.0% (95%-CI: 25.5-30.5%), respectively, had a subsequent colonoscopy within the specified margins. Old age, longer recommended surveillance interval, not having had polypectomy at screening and negative colonoscopy were statistically significant predictors of non-adherence.

Conclusion

This study suggests frequent non-adherence to physician recommendations for surveillance colonoscopy in community practice. Increased efforts to improve adherence, including introduction of more elements of an organized screening program, seem necessary to assure a high-quality CRC screening process.     

Factors associated with practice of colorectal cancer screening among primary care physicians in a Chinese population: A cross-sectional study

Objectives: Primary care physicians (PCPs) are influential in colorectal cancer (CRC) screening uptake in the community. This study aims to evaluate the factors associated with PCPs’ practice of CRC screening among asymptomatic patients in a Chinese population. Methods: A validated postal questionnaire was sent to all practicing PCPs who were members of a community-based network in Hong Kong. Three separate rounds of reminder letters were sent to non-respondents. Binary logistic regression analysis was used with ever-referral for CRC screening in the past 12 months as the outcome variable. Predictor variables include physicians’ gender, clinical experience, types of practice, and attitudes towards CRC screening. Results: Of 428 eligible physicians, 263 (61.4%) responded. A total of 187 physicians (71.1%) had referred patients for CRC screening in the past 1 year. Among all asymptomatic patients aged 50 years or older, physicians reported referring only 3.0% (1.0–10.0%) [median (interquartile range)] of patients. Colonoscopy (57.0%) and fecal occult blood testing (FOBT) (46.4%) were the most commonly recommended tests for these asymptomatic patients. Family history of CRC (58.6%) and patients’ concern about CRC (50.2%) were major reasons for referral. PCPs in private practice (adjusted odds ratio [aOR] 2.60, 95% C.I. 1.21–5.59) and those with positive attitude towards CRC screening (aOR 2.27, 95% C.I. 1.15–4.48) were more likely to recommend CRC screening. Conclusions: PCPs’ attitude towards CRC screening is a significant determinant of its practice. Future studies should identify and strengthen the influencers of PCPs’ attitude to enhance CRC screening rates.     

Evaluating the long-term effect of FOBT in colorectal cancer screening

BackgroundCancer screening has been effective in detecting tumors early before symptoms appear. However, the effectiveness of the regular fecal occult blood test (FOBT) in colorectal cancer in the long term has not been quantified.MethodsWe applied the statistical method developed by Wu and Rosner [1] using data from the Minnesota Colon Cancer Control Study (MCCCS). All initially asymptomatic participants were classified into four mutually exclusive groups: true-early-detection, no-early-detection, over-diagnosis, and symptom-free life; human lifetime was treated as a random variable and is subject to competing risks. All participants in the screening program will eventually fall into one of the four outcomes above. Predictive inferences on the percentages of the four outcomes for both genders were made using the Minnesota study data.ResultsDepending on gender, screening frequency and age at the initial screening, for all participants the probability of “symptom-free-life” varies between 95.3% and 96.6%; the probability of “true-early-detection” is 1.9–3.8%; the probability of no-early-detection is 0.3–2.0%; the probability of over-diagnosis is 0.16–0.3%. Among those with colorectal cancer detected by regular FOBT, the probability of over-diagnosis is lower than expected and is between 6% and 9%, with 95% CI (2.5%, 21.3%) for females and (1.9%, 44.7%) for males. The probability of true-early-detection increases as screening interval decreases. The probability of no-early-detection decreases as screening interval decreases.ConclusionThe probability of over-diagnosis among the screen-detected cases is not as high as previously thought. We hope this outcome can provide valuable information on the effectiveness of the FOBT in colorectal cancer detection in the long term.     

Factors Associated with Adenoma Detection Rate and Diagnosis of Polyps and Colorectal Cancer during Colonoscopy in France: Results of a Prospective,Nationwide Survey

Introduction

Colonoscopy can prevent deaths due to colorectal cancer (CRC) through early diagnosis or resection of colonic adenomas. We conducted a prospective, nationwide study on colonoscopy practice in France.

Methods

An online questionnaire was administered to 2,600 French gastroenterologists. Data from all consecutive colonoscopies performed during one week were collected. A statistical extrapolation of the results to a whole year was performed, and factors potentially associated with the adenoma detection rate (ADR) or the diagnosis of polyps or cancer were assessed.

Results

A total of 342 gastroenterologists, representative of the overall population of French gastroenterologists, provided data on 3,266 colonoscopies, corresponding to 1,200,529 (95% CI: 1,125,936-1,275,122) procedures for the year 2011. The indication for colonoscopy was CRC screening and digestive symptoms in 49.6% and 38.9% of cases, respectively. Polypectomy was performed in 35.5% of cases. The ADR and prevalence of CRC were 17.7% and 2.9%, respectively. The main factors associated with a high ADR were male gender (p=0.0001), age over 50 (p=0.0001), personal or family history of CRC or colorectal polyps (p<0.0001 and p<0.0001, respectively), and positive fecal occult blood test (p=0.0005). The prevalence of CRC was three times higher in patients with their first colonoscopy (4.2% vs. 1.4%; p<0.0001).

Conclusions

For the first time in France, we report nationwide prospective data on colonoscopy practice, including histological results. We found an average ADR of 17.7%, and observed reduced CRC incidence in patients with previous colonoscopy.     

Evaluation of a colorectal cancer screening program composed of successive waves of different tests: The experience of the French Calvados County

BackgroundsThe value of colorectal cancer (CRC) screening program in a population with a limited participation rate is debated. This study assesses the real-life performances of different screening tests in a population benefiting from an organized program and included in a cancer registry.MethodsPatients who participated in at least one screening campaign between 2004 and 2016 were included. Four screening procedures were used: Hemoccult II, Magstream, Hemoccult and Magstream combined, and OC Sensor. Data were crossed with the Digestive Cancer Registry of Calvados to detect CRCs diagnosed during this period. The main outcomes were CRC detection and the incidence rate of interval cancers.ResultsScreening consisted of 325,083 tests in 134,498 patients. Of the 2580 CRCs detected in patients aged 50–74, 534 (20.7 %) were screen-detected. OC Sensor had the highest sensitivity for CRC detection (83.7 %, 95 % CI [76.8–89.1 %]) and the lowest interval cancer rate (2.0 per 10,000 person-years, 95 % CI [1.4–2.7]) compared with other screening tests, excluding combinations. The overall participation rate was 28.9 %.ConclusionReal-life differences in performance between different screening tests exist, and OC Sensor appears to be the best. The low participation rate suggests that the rate of screen-detected CRC could be higher.     

Colorectal cancer incidence in Germany: Stage-shift 6 years after implementation of a colonoscopy screening program

Background: In 2002, colonoscopy was introduced as a tool for colorectal cancer screening in Germany. The long-term objective was to reduce the incidence in colorectal cancer (CRC) by detection and removal of advanced adenomas. Currently, the effect of colonoscopy screening on the population-based incidence of CRC in Germany is unknown. Methods: We provide data on stage-specific (age-standardized) incidence rates in three federal states in Germany, 6 years after the implementation of colonoscopy. Results: Between 2002 and 2008 a statistically significant decrease in CRC incidence could be observed (annually 3.0%, 95% confidence interval [CI]: -3.8; -2.2). The decline could be observed in all advanced tumor categories (T2, T3, and T4), whereas the incidence of in situ carcinomas (Tis) increased annually by 51.6% (95% CI: 28.0; 79.4) until 2004, and remained stable until 2008. Conclusion: The observed changes cannot be attributed definitively to the screening activities, but the presented data support a possible causal association.     

A Predictive Model Combining Fecal Calgranulin B and Fecal Occult Blood Tests Can Improve the Diagnosis of Colorectal Cancer

Aim

Current fecal screening tools for colorectal cancer (CRC), such as fecal occult blood tests (FOBT), are limited by their low sensitivity. Calgranulin B (CALB) was previously reported as a candidate fecal marker for CRC. This study investigated whether a combination of the FOBT and fecal CALB has increased sensitivity and specificity for a diagnosis of CRC.

Materials and Methods

Patients with CRC (n = 175), and healthy individuals (controls; n = 151) were enrolled into the development (81 cases and 51 controls) and validation (94 cases and 100 controls) sets. Stool samples were collected before bowel preparation. CALB levels were determined by western blotting. FOBT and fecal CALB results were used to develop a predictive model based on logistic regression analysis. The benefit of adding CALB to a model with only FOBT was evaluated as an increased area under the receiver operating curve (AUC), partial AUC, and reclassification improvement (RI) in cases and controls, and net reclassification improvement (NRI).

Results

Mean CALB level was significantly higher in CRC patients than in controls (P<0.001). CALB was not associated with tumor stage or cancer site, but positivity on the FOBT was significantly higher in advanced than in earlier tumor stages. At a specificity of 90%, the cross-validated AUC and sensitivity were 89.81% and 82.72%, respectively, in the development set, and 92.74% and 79.79%, respectively, in the validation set. The incremental benefit of adding CALB to the model, as shown by the increase in AUC, had a p-value of 0.0499. RI in cases and controls and NRI all revealed that adding CALB significantly improved the prediction model.

Conclusion

A predictive model using a combination of FOBT and CALB may have greater sensitivity and specificity and AUC for predicting CRC than models using a single marker.     

Relative impact of earlier diagnosis and improved treatment on survival for colorectal cancer: A US database study among elderly patients

PurposesTo estimate what proportion of improvement in relative survival was attributable to smaller stage/size due to early detection and what proportion was attributable to cancer chemotherapy in patients with colorectal cancer (CRC).MethodsWe studied 69,718 patients with CRC aged ≥66 years in 1992–2009 from Surveillance, Epidemiology, and End Results registries. Study periods were categorized into three periods according to the major changes or advances in screening and chemotherapy regimens: (1) Period-1 (1992–1995), during which there was no evidence-based recommendation for routine CRC screening and 5-fluorouracil was the mainstay for chemotherapy; (2) Period-2 (1996–2000), during which evidences and guidelines supported the use of fecal occult blood test (FOBT) and sigmoidoscopy for routine CRC screening; and (3) Period-3 (2001–2009), during which Medicare Program added the full coverage for colonoscopy screening to average-risk individuals, and several newly developed chemotherapy regimens were approved. Outcome variables included the likelihood of being diagnosed at an early stage or with a small tumor size, and improvement in relative survival.ResultsCompared to period-1, likelihood of being diagnosed with early stage CRC increased by 20% in period-2 (odds ratio = 1.2, 95%CI: 1.1–1.2) and 30% in period-3 (1.3, 1.2–1.4); and likelihood of being diagnosed with small-size CRC increased by 60% in period-2 and 110% in period-3. Similarly, 5-year overall relative survival increased from 51% in period-1 to 56% in period-2 and 60% in period-3. Increase in survival attributable to migration in stage/size was 9% in period-2 and 20% in period-3, while the remaining survival improvement during period-2 and period-3 were largely attributable to more effective chemotherapy regimens (≥71.6%) and other treatment factors (≤25%).ConclusionsImprovements in CRC screening resulted in a migration of CRC toward earlier tumor stage and smaller size, which contributed to ≤20% of survival increase. Survival improvement over the past 2 decades was largely explained by more effective chemotherapy regimens (≥71.6%).     

Association between family history of malignant neoplasm with colorectal adenomatous polyp in 40s aged relative person

PurposeWe assessed the association between a family history of malignancy and risk of colorectal adenoma among individuals aged 40–49 years.MethodsThe study population consisted of subjects, aged in their 40s, who underwent colonoscopy. Their family histories of cancer were collected with a self-administered questionnaire. A logistic regression model was used to assess the association between a family history of cancer and the risk of colorectal polyp.ResultsIn total, 2275 participants were included in the study. Univariate analysis showed that old age, male sex, current cigarette smoking, BMI > 25 kg/m², and a family history of colorectal cancer (CRC) were risk factors for the development of sporadic colorectal adenomatous polyps in these patients. A multivariate analysis showed that a family history of CRC or kidney cancer was associated with adenoma development. A family history of CRC was also a risk factor for advanced and multiple adenoma.ConclusionsThis study shows that a family history of CRC is a risk factor for advanced and multiple colorectal adenoma in people in their 40s. These results support earlier screening for colorectal neoplasms in individuals with a family history of CRC.     

Fecal occult blood testing instructions and impact on patient adherence

IntroductionAlthough the physician's role with patients is crucial in encouraging FOBT screening, the nature and content of physician-patient discussions about FOBT screening is unclear. As part of a larger study, this paper reports on our analyses of physician beliefs about fecal occult blood testing (FOBT) and strategies they employed to enhance patient adherence. The second aim of this paper is to report on the perceptions of individuals at average risk for colorectal cancer (CRC) in regard to their awareness of the FOBT and their responses to physician recommendations about FOBT screening.MethodsThe larger study was conducted in urban and rural Manitoba, Canada between 2008 and 2010. We used a qualitative design and conducted semi-structured, audio-recorded interviews with 15 physicians and 27 individuals at average risk for CRC. We included data from 11 family members or friends on their perspectives of FOBT instructions as individuals who were also at average risk for CRC and had their own experiences with CRC screening recommendations.ResultsDespite widespread knowledge of The Canadian Task Force on Preventive Health Care CRC screening guidelines, physician attitudes, behaviors, and instructions were not uniform in promoting patient adherence to FOBT screening. Individuals at average-risk for CRC identified that FOBT instructions were confusing and burdensome, which in turn served as a barrier in their adherence to FOBT screening.ConclusionsVariation in FOBT instruction counseling in relation to the recommended age of individuals at average risk for CRC, as well as adequate patient preparation affected patient adherence. We recommend uniform or standardized instructions and counseling by health care providers who administer the FOBT kit to patients to promote adherence to recommended CRC screening.     

Meat-derived carcinogens,genetic susceptibility and colorectal adenoma risk

Exposure to heterocyclic aromatic amines (HAAs), carcinogens produced when meat is cooked at high temperatures, is an emerging risk factor for colorectal cancer (CRC). In a cross-sectional study of 342 patients undergoing a screening colonoscopy, the role of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx), the three most abundant HAAs found in cooked meats, and total mutagenic activity in cooked meats were examined in relation to colorectal adenoma risk. Given that genetic differences in the ability to biotransform HAAs and repair DNA are postulated to modify the HAA–CRC relationship, gene–diet interactions were also examined. Among the total study population, no relationships were observed between dietary HAAs or meat mutagenicity, and colorectal adenoma risk; however, in males, positive associations between dietary HAAs/meat mutagenicity exposures and adenoma risk were suggestive of a relationship. In a separate analysis, polymorphisms in CYP1B1 were found to be associated with colorectal adenoma risk. Additionally, gene–diet interactions were observed for dietary PhIP and polymorphisms in CYP1B1 and XPD, dietary DiMeIQx and XPD polymorphisms, and meat mutagenicity exposure and CYP1B1 polymorphisms. Overall, increased colorectal adenoma risk was observed with higher HAA/meat mutagenicity exposures among those with polymorphisms which confer greater activity to biotransform HAAs and/or lower ability to repair DNA. This research supports the link between dietary HAAs and genetic susceptibility in colorectal adenoma etiology. The vast majority of CRCs arise from colorectal adenomas; thus, the results of this study suggest that changes in meat preparation practices limiting the production of HAAs may be beneficial for CRC prevention.     

The Detection of the Methylated Wif-1 Gene Is More Accurate than a Fecal Occult Blood Test for Colorectal Cancer Screening

Background

The clinical benefit of guaiac fecal occult blood tests (FOBT) is now well established for colorectal cancer screening. Growing evidence has demonstrated that epigenetic modifications and fecal microbiota changes, also known as dysbiosis, are associated with CRC pathogenesis and might be used as surrogate markers of CRC.

Patients and Methods

We performed a cross-sectional study that included all consecutive subjects that were referred (from 2003 to 2007) for screening colonoscopies. Prior to colonoscopy, effluents (fresh stools, sera-S and urine-U) were harvested and FOBTs performed. Methylation levels were measured in stools, S and U for 3 genes (Wif1, ALX-4, and Vimentin) selected from a panel of 63 genes; Kras mutations and seven dominant and subdominant bacterial populations in stools were quantified. Calibration was assessed with the Hosmer-Lemeshow chi-square, and discrimination was determined by calculating the C-statistic (Area Under Curve) and Net Reclassification Improvement index.

Results

There were 247 individuals (mean age 60.8±12.4 years, 52% of males) in the study group, and 90 (36%) of these individuals were patients with advanced polyps or invasive adenocarcinomas. A multivariate model adjusted for age and FOBT led to a C-statistic of 0.83 [0.77–0.88]. After supplementary sequential (one-by-one) adjustment, Wif-1 methylation (S or U) and fecal microbiota dysbiosis led to increases of the C-statistic to 0.90 [0.84–0.94] (p = 0.02) and 0.81 [0.74–0.86] (p = 0.49), respectively. When adjusted jointly for FOBT and Wif-1 methylation or fecal microbiota dysbiosis, the increase of the C-statistic was even more significant (0.91 and 0.85, p<0.001 and p = 0.10, respectively).

Conclusion

The detection of methylated Wif-1 in either S or U has a higher performance accuracy compared to guaiac FOBT for advanced colorectal neoplasia screening. Conversely, fecal microbiota dysbiosis detection was not more accurate. Blood and urine testing could be used in those individuals reluctant to undergo stool testing.     

Colorectal cancer screening for average-risk North Americans: an economic evaluation

Background

Colorectal cancer (CRC) fulfills the World Health Organization criteria for mass screening, but screening uptake is low in most countries. CRC screening is resource intensive, and it is unclear if an optimal strategy exists. The objective of this study was to perform an economic evaluation of CRC screening in average risk North American individuals considering all relevant screening modalities and current CRC treatment costs.

Methods and Findings

An incremental cost-utility analysis using a Markov model was performed comparing guaiac-based fecal occult blood test (FOBT) or fecal immunochemical test (FIT) annually, fecal DNA every 3 years, flexible sigmoidoscopy or computed tomographic colonography every 5 years, and colonoscopy every 10 years. All strategies were also compared to a no screening natural history arm. Given that different FIT assays and collection methods have been previously tested, three distinct FIT testing strategies were considered, on the basis of studies that have reported “low,” “mid,” and “high” test performance characteristics for detecting adenomas and CRC. Adenoma and CRC prevalence rates were based on a recent systematic review whereas screening adherence, test performance, and CRC treatment costs were based on publicly available data. The outcome measures included lifetime costs, number of cancers, cancer-related deaths, quality-adjusted life-years gained, and incremental cost-utility ratios. Sensitivity and scenario analyses were performed. Annual FIT, assuming mid-range testing characteristics, was more effective and less costly compared to all strategies (including no screening) except FIT-high. Among the lifetimes of 100,000 average-risk patients, the number of cancers could be reduced from 4,857 to 1,782 and the number of CRC deaths from 1,393 to 457, while saving CAN$68 per person. Although screening patients with FIT became more expensive than a strategy of no screening when the test performance of FIT was reduced, or the cost of managing CRC was lowered (e.g., for jurisdictions that do not fund expensive biologic chemotherapeutic regimens), CRC screening with FIT remained economically attractive.

Conclusions

CRC screening with FIT reduces the risk of CRC and CRC-related deaths, and lowers health care costs in comparison to no screening and to other existing screening strategies. Health policy decision makers should consider prioritizing funding for CRC screening using FIT. Please see later in the article for the Editors'' Summary     

General practitioner and specialist views on colonoscopic screening of first-degree relatives of colorectal cancer patients

Introduction: Barriers to targeted colonoscopic screening of first-degree relatives of colorectal cancer patients have been the subject of considerable literature, always as seen from the patient's viewpoint. In the specific context of screening individuals with a family history, physicians may also play a predominant role in motivating their colorectal cancer patients to pass on screening information to their relatives. The aim of this study was to examine the views of general practitioners and specialists regarding barriers and facilitators affecting participation of relatives in colonoscopic screening. Methods: A qualitative study was conducted to collect and analyse information from two focus groups of 4 general practitioners and 9 gastroenterologists respectively, and from semi-structured individual interviews with 10 general practitioners, 2 surgeons and 3 oncologists. An extended focus group of 36 gastroenterologists was organized to validate the results. Results: The main barriers to colonoscopic screening of FDRs were associated with lack of direct communication between physicians and FDRs. Physicians needed support in the task of informing index patients and persuading them to transfer information on screening to their FDRs. The general practitioners spoke of their expectations in terms of training in and motivation for promoting screening and the gastroenterologists expressed the wish for patient education material specific to colonoscopy and for systematic post-colonoscopy consultations to inform patients about their results, follow-up and screening their relatives. Conclusion: The findings, notably the need for specific education materials and for training to improve the motivation of physicians, will help to develop effective interventions intended to increase participation in screening.