Welcome!Colorectal screening

evidence & Colonoscopy screening

guidelines

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What’s the evidence for the guidelines? Review evidence:Fitzpatrick-Lewis, D., Usman, A., Warren, R., Kenny, M., Rice, M., Bayer, A., Ciliska, D., Sherifali, D., Raina, P. Screening for colorectal cancer. Ottawa: Canadian Task Force on Preventive Health Care; 2015. Available: www.canadiantaskforce.ca/ ctf phc-guidelines/2015-colorectal-cancer/systematic-review 

Screening guidelines:Bacchus, C. M., Dunfield, L., Gorber, S. C., Holmes, N. M., Birtwhistle, R., Dickinson, J. A., Lewin, G., Singh, H., Klarenbach, S., Mai, V., Tonelli, M. (2016). Recommendations on screening for colorectal cancer in primary care. Canadian Medical Association Journal, cmaj-151125.

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The Health Evidence™ Team

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inform

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A Model for Evidence-Informed Decision

Making

National Collaborating Centre for Methods and Tools. (revised 2012). A Model for Evidence-Informed Decision-Making in Public Health (Fact Sheet). [http://www.nccmt.ca/pubs/FactSheet_EIDM_EN_WEB.pdf]

Stages in the process of Evidence-Informed Public Health

National Collaborating Centre for Methods and Tools. Evidence-Informed Public Health. [http://www.nccmt.ca/eiph/index-eng.html]

Poll Question #3

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Searchable Questions Think “PICOS”

1. Population (situation)

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A.AlwaysB.OftenC.SometimesD.NeverE.I don’t know what a systematic review is

Poll Question #4

Maria Bacchus

Associate Professor of Medicine, Faculty of

Medicine University of Calgary, and member of

the Canadian Task Force on Preventive Health Care

Donna Fitzpatrick-

Lewis

MSW, Senior Research Coordinator at the Effective

Public Health Practice Project (EPHPP)

Putting Preventioninto Practice

Canadian Task Force on Preventive Health CareGroupe d’étude canadien sur les soins de santé préventifs

Recommendations on Screening for Colorectal

Cancer 2016

Canadian Task Force on Preventive Health Care (CTFPHC)

CTFPHC Working Group Members

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*non-voting member

Overview of Presentation

• Background on Colorectal Cancer • Methods of the CTFPHC• Recommendations and Key Findings• Implement our Recommendations• Conclusions • Questions and Answers

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Background – Canadian perspective

• Colorectal cancer (CRC) is the second most common cause of cancer mortality in men and the third most common in women with a current lifetime probability of dying from this disease of 3.5% and 3.1% respectively

• The incidence and mortality of CRC are low until middle age, and rise rapidly thereafter

• It is estimated that 25,000 Canadians were diagnosed with CRC in 2015 and 9,300 died from the disease

• Most CRCs appear to arise from colonic polyps that develop slowly, some of which transform to cancers

• CRC screening programs aim to reduce deaths by detecting and removing polyps and/or early stage CRCs

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Background - Guideline Objectives

• The purpose of this guideline is to present recommendations for screening for CRC in asymptomatic adults aged 50 and older who are not at high risk for CRC and to update previous CTFPHC recommendations (2001)

• This guideline provides guidance for primary care practitioners on different screening tests, screening intervals and recommended ages to start and stop screening

• These guidelines do not apply to those with previous CRC or polyps, inflammatory bowel disease, signs or symptoms of CRC, history of CRC in one or more first degree relatives, or adults with hereditary syndromes predisposing to CRC such as familial adenomatous polyposis or Lynch Syndrome22

Screening Tests for Colorectal Cancer

• Fecal occult blood testing (FOBT) – Tests include guaiac fecal occult blood testing (gFOBT) and

fecal immunochemical testing (FIT)– The patient provides a stool sample that will be tested for

blood that cannot be seen with the naked eye

• Endoscopies – Tests include flexible sigmoidoscopy and colonoscopies – A long flexible tube with a light and camera attached is

inserted into the anus, rectum, and lower colon of the patient to look for polyps

– Before this procedure, patients will need to cleanse their bowels with enemas or laxatives

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Methods of the CTFPHC

• Independent panel of:– Clinicians and methodologists – Expertise in prevention, primary care, literature

synthesis, and critical appraisal– Application of evidence to practice and policy

• Colorectal Cancer Working Group– 7 Task Force members– Establish research questions and analytical framework

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Methods of the CTFPHC

• McMaster Evidence Review and Synthesis Centre (MERSC) – Undertook a systematic review of the literature based on

the analytical framework– Prepared a systematic review of the evidence with

GRADE tables – Participated in working group and task force meetings – Obtained expert opinions

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CTFPHC Review Process• Internal review process involving

guideline working group, Task Force, scientific officers and ERSC staff

• External review process involving key stakeholders – Generalist and disease specific stakeholders– Federal and P/T stakeholders, also occurred• Finally, the CMAJ undertook an independent peer review

journal process to review guidelines

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Analytical Framework

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Mortality (all-cause and cancer mortality); Incidence

of late stage colorectal cancer

Screening

Harms of screening (complications of the test

or follow-up; false positive; false negative;

overdiagnosis)

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Asymptomatic adults not at high risk for colorectal cancer

Research Questions • What is the effectiveness of each colorectal cancer screening test to reduce colorectal

cancer-specific mortality, all-cause mortality, or incidence of late stage colorectal cancer in asymptomatic adults who are not at high risk for colorectal cancer?

– What is the optimal age to start and stop screening and the optimal screening interval of asymptomatic adults not at high risk for colorectal cancer?

– What is the evidence that the clinical benefits of screening differ for the various screening tests, or by subgroups that may influence the underlying risk of colorectal cancer?

• What is the incidence of harms of screening for colorectal cancer in adults not at high risk for colorectal cancer? What is the evidence that the harms of screening differ for the various screening tests or by subgroups that may influence the underlying risk of colorectal cancer?

• Screening tests include colonoscopy, flexible sigmoidoscopy, CT colonography, gFOBT, FIT, fecal DNA testing, and other screening tests currently in use identified in the literature search

• Populations at high risk of colorectal cancer (Table 1) will be excluded, such as those with prior colorectal cancer or polyps, signs/symptoms suggesting underlying colorectal cancer, familial adenomatous polyposis, or hereditary non-polyposis colorectal cancer.

P Asymptomatic adults 18 years and older who are not at high risk of colorectal cancer

IScreening with colonoscopy, CT colonography, gFOBT, iFOBT, FS, BE, DRE, fecal DNA, serum DNA, other identified tests currently being used for screening in Canada

C• No screening

• Head to head – two tests compared with each other

O

Mortality (all-cause and colorectal cancer-specific)Incidence of late stage colorectal cancer (stage III or IV; or Duke’s C or D) Sensitivity, specificity, negative and positive predictive value for detection of any stage colorectal cancer for those tests with evidence for screening effectiveness Harms: complications (bleeding [not requiring hospitalization and requiring hospitalization], perforation, death) of the test or follow-up test, false positive, false negative, overdiagnosis

S Primary care, including referrals for tests by primary care practitioners

Search Results

Search Yielded Included

Benefits Test Properties Adverse Events

13,260 citations 9 37 46

Analysis Overview• Risk of Bias assessment was done on all included RCTs for

effectiveness of screening• Benefits of CRC screening – number of events, proportion or

percentage data from included RCTs were used to generate summary measures of effect in form of risk ratio

• Harms of CRC screening and f/u tests – rates/proportions along with 95% confidence intervals across studies were pooled using the DerSimonian and Laird random effects models with inverse variance method to generate summary measures of effect

• Test Properties - Positive predictive value, negative predictive value, sensitivity, specificity and likelihood rations were pooled descriptively using median with range approach

• Primary subgrouping for benefits, harms and test properties was screening method

• Strength of evidence assessed with GRADE

Risk of Bias Assessment of Included RCTs

Study Sequence Generation

Allocation Concealment

Blinding of

Outcome Assessors

Incomplete Reporting

Selective Reporting

Other Bias*

Scholefield 2012 U U L

 

LL U

Schoen 2012

L U

 

U

U L H

Segnan 2011L U L H L U

Atkin 2010

L U

 

L

 

L

L U

Hoff 2009L U L L L L

Lindholm 2008U U L H L U

Kronborg 2004L U L H L U

Zheng 2003L U L U L U

Shaukat 2013U U L U L U

Key Findings - Benefits of ScreeningOutcome gFOBT iFOBT Flexible

SigmoidoscopyCRC-specific mortality

Meta-analysis of 4 moderate quality RCTs of screening with gFOBT on CRC-specific mortality found a RR 0.82 (95%CI, 0.73, 0.92, I2=67%), with an Absolute Risk Reduction (ARR) 2,654/million (1,128-4,010 fewer)

One moderate quality RCT found that screening with iFOBT had a non-significant impact on CRC mortality RR 0.88 (95%CI, 0.72, 1.07)

Meta-analysis of primary screening with flexible sigmoidoscopy showed a relative reduction of 28% in CRC specific mortality with a pooled RR of 0.72 (95% CI; 0.65, 0.81, I2=0%) and an ARR of 1,176 per million (95% CI; 830 to 1,486 fewer)

All-cause mortality

Screening with gFOBT did not reduce all-cause mortality RR 1.00 (95% CI, 1.00-1.00, I2=0%).

No data RR 0.99 (0.97, 1.01, I2=35%)

Incidence of late stage CRC

Screening with gFOBT reduced late stage CRC by 8% RR 0.92 (95%CI, 0.85-0.99, I2 =0%)

No data RR 0.75 (95%CI, 0.66- 0.86, I2=23%); ARR 1,733/million (1,011, 2,368 fewer)

Key Findings – Test PropertiesOutcome gFOBT iFOBTMedian sensitivity 47.1% (range 12.9%-75.0%) 81.5% (range 53.3%-100%)

Median specificity 96.1% (range 90.1%-98.1%) 95.0% (range 87.2%-96.9%)

Median PPV 7.5% (1.5%-15%) 7.35% (range 4.0%-10.8%)

Mean NPV 99.55% (range 99.5%-99.6%) 100% (range 99.7%-100%)

Number needed to screen (NNS)

597 (range 239-936) 209 (range 41-430)

Key Findings – Adverse Events• Greater potential for harms with flexible sigmoidoscopy

(perforation, bleeding (both major and minor) and death)• Few harms associated with gFOBT (non-invasive); false-

positive proportions are low and there are few false-negatives

• False-negatives of iFOBT can lead to unnecessary additional follow-up tests, such as colonoscopy, which can result in other harms (bleeding, infection and on the rare occasion death)

• No RCTS found on harms of barium enema or fecal DNA tests

Contextual Question – Preferences and Values for Screening for Colorectal Cancer• 3 reviews and 20 primary studies were found• Screening tests of focus included FOBT, computed tomography colonoscopy,

and flexible sigmoidoscopy• A survey conducted by the Canadian Partnership Against Cancer with

Canadians aged 45-74 years revealed that the majority of respondents agreed that CRC and early treatment is important; people were aware of screening but not of the specifics of screening; most people indicated colonoscopy as being the primary test and few knew of FOBT. Results implied that lack of education and not embarrassment is a bigger barrier to screening

• Another Canadian study with 40 to 60 year olds in a primary care setting revealed that 29% of participants preferred no screening; preferred test attributes included non-invasive procedures, no preparation, no pain, 100% specificity and 90% sensitivity

• A US study explored decision priorities for patients in primary care; highest priority was preventing cancer (55%), avoiding test side effects (17%), minimizing false positives (15%), and combined priority of screening frequency, test preparation, and test procedures (14%)

How is Evidence Graded?

The “GRADE” System:• Grading of Recommendations, Assessment, Development &

Evaluation

What are we grading?1. Quality of Evidence

– Degree of confidence that the available evidence correctly reflects the theoretical true effect of the intervention or service.

– high, moderate, low, very low

2. Strength of Recommendation– Quality of evidence; the balance between desirable and

undesirable effects; the variability or uncertainty in values and preferences of citizens; and whether or not the intervention represents a wise use of resources.

– strong and weak37

Strength of Recommendations

The strength of the recommendations (strong or weak) are based on four factors:•Quality of supporting evidence •Certainty about the balance between desirable and undesirable effects •Certainty / variability in values and preferences of individuals•Certainty about whether the intervention represents a wise use of resources 38

Interpretation of RecommendationsImplications Strong Recommendation Weak Recommendations

For patients • Most individuals would want the recommended course of action;

• only a small proportion would not.

• The majority of individuals in this situation would want the suggested course of action but many would not.

For clinicians • Most individuals should receive the intervention.

• Recognize that different choices will be appropriate for individual patients;

• Clinicians must help patients make management decisions consistent with values and preferences.

For policy makers

• The recommendation can be adapted as policy in most situations.

• Policy making will require substantial debate and involvement of various stakeholders.

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RECOMMENDATIONS & KEY FINDINGS

Screening for Colorectal Cancer

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Summary of Key Findings Screening tool

Age Risk Ratio

CRC Mortality

95% CI Incidence of late stage CRC

95% CI

FOBT ( 4 RCT MA)

45-80 0.82 0.73-0.92 0.92 0.85-0.99

FS (pooled analysis, 4 RCTs)

55-74 0.72 0.65-0.81 0.75 0.66–0.86

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No RCTs have reported on the mortality benefits of screening colonoscopy,CT colonography, barium enema, DRE or fecal DNA testing

No screening test reduced all cause mortality

Colorectal Cancer 2015 Guidelines

• Provide recommendations for practitioners on preventive health screening in a primary care setting:

• These recommendations apply to adults 50 years and over who are not at high risk for CRC

• These recommendations do not apply to adults with:– Previous CRC or polyps– Inflammatory bowel disease– Signs or symptoms of CRC– History of CRC in one or more first degree relatives – Hereditary syndromes predisposing to CRC, such as

familial adenomatous polyposis or Lynch Syndrome 42

FOBT or FlexSig ScreeningRecommendation 1: We recommend screening adults aged 60 to 74 for CRC with FOBT (either gFOBT or FIT) every two years OR flexible sigmoidoscopy every 10 years. •Strong recommendation; moderate quality evidence

Recommendation 2: We recommend screening adults aged 50 to 59 for colorectal cancer (CRC) with FOBT (gFOBT or FIT) every two years OR flexible sigmoidoscopy every 10 years. •Weak recommendation; moderate quality evidence

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FOBT or Flex Sig Screening: Ages 50-74Basis of the recommendation:•In the judgment of the CTFPHC, FOBT and flexible sigmoidoscopy are both reasonable screening tests for patients aged 50-74 years based on RCT evidence.

•Splitting this recommendation for screening into two age groups places a relatively higher value on the different balance of benefits to harms by age, and a relatively lower value on the added complexity of two recommendations rather than one.

•Although the relative benefits are similar for older (60-74) and younger (50-59) age groups, the absolute benefits are smaller in those 50-59 due to the lower incidence. This warrants a weak recommendation to screen in those aged 50-59 as compared to the strong recommendation for people aged 60-74 years. 44

Not Screening Adults Aged 74+Recommendation 3: We recommend not screening adults aged 75 years and over for colorectal cancer (CRC).•Weak recommendation; low quality evidence

Basis of the recommendation:•Lack of RCT data on benefits of screening in this age group (varied, but upper ages included were 64 years, 74 years, 75 years, and 80 years for gFOBT and 64 years and 74 years for flexible sigmoidoscopy). •Reduced life expectancy in older age groups •Adults over 74 years of age who are healthy (with longer life expectancy) and are less concerned with the lack of reported benefit or the potential harms may choose to be screened.  

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Not Screening Using ColonoscopyRecommendation 4: We recommend not using colonoscopy as a screening test for colorectal cancer (CRC).•Weak recommendation; low quality evidence

Basis of the recommendation:•Although colonoscopy may offer clinical benefits that are similar to or greater than those associated with flexible sigmoidoscopy, direct RCT evidence of its efficacy in comparison to the other screening tests (in particular FIT) is currently lacking.

•In addition to a lack of evidence, there are also issues related to wait lists, resource constraints and a greater potential for harms.  •Patients who are less concerned about the potential harms of colonoscopy and/or who are more interested in a test that allows a longer screening interval may still request screening with colonoscopy.

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NNS for CRC Mortality by Age-Groups with Varying Underlying Baseline Risk

Outcome Screening test Age Group (years) ARR NNS LL-NNS UL-NNS

CRC Mortality Biennial gFOBT < 60 (45 to 59) 0.0377% 2655 1757 6244

CRC Mortality Biennial gFOBT ≥ 60 (60 to 80) 0.2032% 492 326 1157

CRC Mortality Flex Sigmoidoscopy < 60 (45 to 59) 0.0540% 1853 1441 2713

CRC Mortality Flex Sigmoidoscopy ≥ 60 (60 to 80) 0.2912% 343 267 503

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Harms of Screening

• No high quality studies evaluating the harms of screening for colorectal cancer

• Possible harms related to screening include:– Death– Perforation– Bleeding (with or without hospitalization)– False-positive or false-negative – Over-diagnosis

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• Our recommendations are consistent with the previous 2001 CTFPHC guideline

• Provincial screening programs recommend screening with FOBT (the majority recommend FIT) every 1-2 years

• No province currently recommends screening with flexible sigmoidoscopy

• The USPSTF published recommendations in 2008 (currently being updated), and recommended either FOBT, flexible sigmoidoscopy, or colonoscopy

Comparison of Screening for Colorectal Cancer Recommendations

Comparison: CTFPHC guideline vs. USPSTF draft guideline

GUIDELINE CTFPHC (2015) USPSTF DRAFT (2015)

AGE GROUPS &RECOMMENDATIONS

50-59 YEARS SCREEN (WEAK)

50-75 YEARS

SCREEN - Grade A

60-74 YEARS SCREEN (STRONG)

SCREEN - Grade A

> 75 YEARS DO NOT SCREEN (WEAK)

76-80 YEARS

SCREEN - Grade C

CRC SCREENING MODALITIES & INTERVALS

gFOBT or FIT Every 2 years gFOBT or FIT Every year

Flexible Sigmoidoscopy

Every 10 years Flexible Sigmoidoscopy

Every 10 years plus FIT every year

Colonoscopy Do not recommend

Colonoscopy Every 10 years

Implementation - Resources

• We expect that most Canadians will be screened with either FIT or gFOBT due to limited access to and availability of flexible sigmoidoscopy

• Although flexible sigmoidoscopy is not frequently performed for screening in many jurisdictions, it may warrant further consideration as it can be completed in the same facilities as colonoscopy and using similar equipment, but without the requirement of a specialist such as a gastroenterologist

• Screening programs would need to consider the implications of establishing screening facilities such as training of providers, the bowel preparation required by patients and the resources needed for flexible sigmoidoscopy as compared to FOBT

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Values and Preferences of CRC Screening• A Canadian survey on screening test preferences

indicated that invasiveness, level of preparation required and pain from the test were concerns.

• A US study rated patient priorities as preventing cancer (55%), avoiding test side effects (17%), minimizing false positives (15%) and the combination of screening frequency, test preparation and test procedures (14%).

• When patients have the option of screening tests, sedation needs, perceived test accuracy, confidence in completing the test, bowel preparation and frequency of tests may influence decision.

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Knowledge Translation Tools

• The CTFPHC creates KT tools to support the implementation of guidelines into clinical practice

• A clinician recommendation table and patient FAQ have been developed for the colorectal cancer guideline

• These tools are freely available for download in both French and English on the website: www.canadiantaskforce.ca

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Conclusions

• The CTFPHC recommends that starting at age 50 age, primary care providers should discuss the most appropriate choice of test with patients who are interested in screening

• Screening for CRC with FOBT or flexible sigmoidoscopy reduces CRC mortality and the direct harms associated with these tests are minimal

• The strong recommendation to screen adults aged 60-74 years with gFOBT, FIT or flexible sigmoidoscopy indicates that primary care providers should offer this service to all individuals in this age group

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Conclusions• The weak recommendation to screen adults aged 50-59

years with gFOBT, FIT or flexible sigmoidoscopy indicates that a more nuanced discussion of the harms and benefits will be required

• Starting at age 75, primary care providers should discuss individual screening preferences

• The CTFPHC recommends not using colonoscopy as a screening tool at this time based on the lack of high quality RCT data. Four trials are currently underway investigating the mortality benefit of screening with colonoscopy. These will be considered by the CTFPHC as the results become available.

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Update: CTFPHC Mobile App Now Available

• The app contains guideline and recommendation summaries, knowledge translation tools, and links to additional resources.

• Key features include the ability to bookmark sections for easy access, display content in either English or French, and change the font size of text.

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Take Home Messages• CRC is a common cause of cancer mortality

• We can reduce mortality from CRC – screening with FOBT and Flexible sigmoidoscopy have been shown to decrease mortality from CRC in those aged 50-74

• Individuals over the age of 50 should discuss screening for CRC with their primary care providers

• Patient values and preferences, test availability and life expectancy should be considered in determining the best screening options for individuals

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Update: CTFPHC on Social Media

• The CTFPHC is venturing into social media!

• A Twitter policy and strategy is currently being developed

• Please check the CTFPHC website for updates: http://canadiantaskforce.ca/

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More Information

For more information on the details of this guideline please see:

• Canadian Task Force for Preventive Health Care website: http://canadiantaskforce.ca/?content=pcp

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Questions?

Poll Question #5

The information presented today was helpful

A.Strongly agreeB.AgreeC.NeutralD.DisagreeE.Strongly disagree

A Model for Evidence-Informed Decision

Making

National Collaborating Centre for Methods and Tools. (revised 2012). A Model for Evidence-Informed Decision-Making in Public Health (Fact Sheet). [http://www.nccmt.ca/pubs/FactSheet_EIDM_EN_WEB.pdf]

Poll Question #6What are your next steps?

A.Access the full text systematic review and screening guidelines

B.Access the quality assessment for the review on www.healthevidence.org

C.Consider using the evidence / recommendations D.Tell a colleague about the evidence /

recommendations

What can I do now? Visit the website; a repository of over 4,600 quality-rated systematic reviews related to the effectiveness of public health interventions. Health Evidence™ is FREE to use.Register to receive monthly tailored registry updates AND monthly newsletter to keep you up to date on upcoming events and public health news.Tell your colleagues about Health Evidence™: helping you use best evidence to inform public health practice, program planning, and policy decisions! Follow us @Health Evidence on Twitter and receive daily public health review-related Tweets, receive information about our monthly webinars, as well as announcements and events relevant to public health. Encourage your organization to use Health Evidence™ to search for and apply quality-rated review level evidence to inform program planning and policy decisions. Contact us to suggest topics or provide feedback.

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FOBT & FLEX Sigmoidoscopy Screening Intervals• CTFPHC selected a 2 year screening interval for FOBT

(gFOBT and FIT) as this was the interval most commonly used in gFOBT RCTs– RCT data showed no significant difference found between annual

and biennial screening on CRC specific mortality

• CTFPHC selected a 10 years screening interval for Flex Sig. based on three factors:– Data show a reduction in CRC mortality and incidence until 11

years of follow-up– RCT data show beneficial effects of screening are maintained over

follow-up period – Observational data show mortality benefits last for at least 10-15

years

Research Gaps

• Trials investigating mortality benefit of CRC screening are underway: Northern European Initiative on CRC (2026); Screening of Swedish COlons (2034); Barcelona (2021); and CONFIRM (2025).

• Trials demonstrating a mortality benefit of colonoscopy, fecal DNA assays, and other tests are needed before they can be recommended for population-based screening.

• Research about how to increase access to colonoscopy in Canada would be useful to inform population-based screening with this test.

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Research Gaps

• More data are needed on effectiveness of FIT in all age groups, on all screening tests in populations aged less than 60 years or older than 74 years and on the impact of screening on overdiagnosis and overtreatment-monitoring for these harmful outcomes at a national level is recommended to address this research gap.

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