Colorectal screening evidence & colonoscopy screening guidelines

Welcome!
Colorectal screening
evidence & Colonoscopy
screening guidelines
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3

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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Searchable Questions Think “PICOS”
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4. Outcomes
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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 Prevention
into Practice
Canadian Task Force on Preventive Health Care
Groupe 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
19
*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
20

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
21

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 Syndrome
22

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
23

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
24

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
25

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
26

Analytical Framework
27
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)
3
12
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
I
Screening 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
L
L U
Schoen 2012
L U U U L H
Segnan 2011
L U L H L U
Atkin 2010
L U L L L U
Hoff 2009
L U L L L L
Lindholm 2008
U U L H L U
Kronborg 2004
L U L H L U
Zheng 2003
L U L U L U
Shaukat 2013
U U L U L U

Key Findings - Benefits of Screening
Outcome gFOBT iFOBT Flexible
Sigmoidoscopy
CRC-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 Properties
Outcome gFOBT iFOBT
Median 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 weak
37

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 Recommendations
Implications 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.
39

RECOMMENDATIONS &
KEY FINDINGS
Screening for Colorectal Cancer
40

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
41
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 Screening
Recommendation 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
43

FOBT or Flex Sig Screening: Ages
50-74
Basis 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
•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.
45

Not Screening Using Colonoscopy
Recommendation 4: We recommend not using colonoscopy as a screening
test for colorectal cancer (CRC).
•Weak recommendation; low quality evidence
•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.
46

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
47

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
48

49
• 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
51

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.
52

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
53

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
54

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.
55

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.
56

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
57

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/
58

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
59

Poll Question #5
The information presented today was helpful
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C.Neutral
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E.Strongly disagree

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guidelines
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www.healthevidence.org
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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.
67

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.
68

Colorectal screening evidence & colonoscopy screening guidelines

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