Review for 10.1186/1471-230X-12-183 (2012)

Reviewer's report
Title:Colorectal cancer screening: Why immunochemical fecal occult blood tests
are the best option.
Version: 1Date:9 November 2012
Reviewer: Thomas de Wijkerslooth
Reviewer's report:
General considerations:
The authors discussed three alternative objectives for colorectal cancer
screening: minimising harms, optimising economic efficiency and maximising
equity of access. The manuscript is well written and interesting. All objectives are
valid, however it seems remarkable that the primary objective of screening for
CRC – reduction of CRC-related mortality – has not been described at all. To my
opinion, all described objectives should be secondary objectives in screening for
CRC. That should be stated more carefully.
Title:
The authors may be somewhat prepossessed in favour of FOBT. I would suggest
to change the title into: Colorectal cancer screening: Why immunochemical fecal
occult blood tests may be the best option.
Background:
First paragraph:
1. The authors did mention some screening tests, but did not describe the
performance and possible advantages and disadvantages of each screening test.
It would be logical to discuss the use and characteristics of each test in the
background to understand the three alternative objectives further on.
2. The authors mentioned six possible screening tests, but forget two other
possible screening tests: capsule endoscopy and MR-colonography. I would
suggest describing the most used and studied screening tests worldwide: FOBT,
sigmoidoscopy, colonoscopy and CT-colonography. Nowadays, DCBE is
considered to be an inferior modality and surpassed by CT-colonography. Stool
marker tests, capsule endoscopy and MR colonography should not be used for
CRC screening at this moment, but have potential for the future.
Second and third paragraph:
Excellent to refer to two major US guidelines to introduce the three alternative
objectives.
Fourth paragraph:
3. It is not clear why the authors believe maximizing participation should not be
the primary aim of a screening test. In fact, a population screening program with
a participation rate of 0% would not reduce CRC-related mortality which should
be the primary aim of screening. Possibly, high participation rates are not
necessary to ensure cost-effectiveness, but that’s not the (primary) objective of
screening. Please explain the following sentence in this paragraph in more detail
and ground your statement with more literature:
“In contrast, we believe that maximizing participation should not be a primary aim
of a screening program: not everyone will want to be screened, and high
screening participation rates are not necessary to ensure cost-effectiveness.”
Alternative objectives:
Minimization of harms:
4. Minimization of harms may be a valid objective. Obviously, the “best”
minimization of harms would be to not participate in screening. I presume the
authors do not want to advocate this. To place it into context, I would suggest
describing the primary objective of screening first (reduction of CRC-related
mortality) to explain that minimization of harms may be one of the surrogate
objectives for screening.
Optimization of economic efficiency:
5. The authors state that the purpose of screening is not to diagnose a disease
but to identify those at higher risk of having this disease. With each screening
test, except for colonoscopy, it is possible to identify those with a higher risk (a
positive FOBT, a positive sigmoidoscopy or a positive CT-colonography.
Colonoscopy is the reference standard. This should be described more carefully.
The authors are somewhat prepossessed in favour of FOBT by mentioning
FOBT to be highly cost-effective. In fact, all screening tests are considered
cost-effective. I would suggest removing the last sentence of the paragraph.
Applying these alternative objectives to CRC screening:
Minimization of harms:
6. This paragraph describes the disadvantages of colonoscopy and
sigmoidoscopy and the advantages of FOBT. CT-colonography is not mentioned
at all. Again, the authors are prepossessed in favour of FOBT. This paragraph
should be well-balanced by describing all advantages and disadvantages of the
screening tests (or in the background as I stated above). For example,
FOBT-screening will burden individuals by repeated rounds of screening (annual
or biannual) while colonoscopy may be performed one time in 10 years.
Therefore it may be possible that colonoscopy screening will lead to minimization
of harms over a 10 year period.
7. A possible strategy to minimize the harms may be by defining specific age –or
sex groups. The prevalence of advanced adenomas were comparable between
men aged 45 to 49 years and women aged 55 to 59 years (JAMA, September
28, 2011—Vol 306, No. 12). Those with a higher risk for CRC or advanced
adenoma can be invited in an earlier stage, those with a lower risk can be invited
at a later stage. This would lead to a minimization of harms in the lower risk
group. I would suggest adding such a paragraph.
8. Please also refer to Atkin WS et al. (Lancet. 2010 May 8;375(9726):1624-33)
by describing effectiveness of screening.
Optimization of economic efficiency:
9. The authors want to restrict colonoscopy for those at the highest risk which
lead to lower costs. That is possible by defining specific (age or sex) groups with
a higher risk of CRC, as the authors stated. However the main advantage of
iFOBT is that it is possible to adapt the cut-off level to the colonoscopy capacity.
Although FIT is more cost-effective at a lower cut-off level (Gastroenterology.
2011 Nov;141(5):1648-55), adapting the cut-off level may be a good option when
colonoscopy capacity is limited (J Natl Cancer Inst. 2011 Dec
7;103(23):1741-51). I would suggest adding a paragraph that discusses the
possibility to adapt the cut-off level for FIT.
Maximising equity of access:
The authors describe a good point. Equity of access to screening is important
and all countries realize that specific groups may be have less access to
screening.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that I have no competing interests