Review for 10.1186/1471-230X-11-65 (2011)

Reviewer's report
Title:Most bowel symptoms do not indicate colorectal cancer and polyps: a
systematic review
Version: 1Date:28 October 2010
Reviewer: Tom Marshall
Reviewer's report:
Most bowel cancer symptoms do not indicate colorectal cancer and polyps: a
systematic review
Barbara-Ann Adelstein, Petra Macaskill, Siew F Chan, Peter H Katelaris, Les
Irwig
Overall comment
This is a systematic review of the evidence for association between symptoms
and a diagnosis of colorectal cancer. It is an appropriate approach to a clinically
relevant question.
The review appears to have been conducted well and reasonably written up. The
papers identified and reviewed are appropriate.
The findings are not very novel and mainly draw attention to the variable quality
of research in this area. The discussion could be improved by including some
further comment on the papers reviewed, problems with consistency of data
extraction and reference to some recent literature (probably published at about
the time the paper was submitted).
Major compulsory revisions
Abstract
The abstract is clear however some information is not included in the abstract.
• The authors should clarify whether the studies were selected on the basis of
study methodology (case control, cohort or retrospective cohort) or entirely on
the basis of whether a 2x2 table could be constructed (which is theoretically
possible with a cross-sectional study).
• The authors should clarify in the abstract whether the studies concerned were
only of symptoms in patients presenting to primary care or first contact health
professionals or included patients referred by primary care / first contact health
professionals to secondary care professionals.
Methods
The search strategy seems reasonable although the inclusion criteria are
described. Data extraction is described.
• The observation that there were issues of uncertainty or discrepancy between
the data extraction sets in 50% of papers probably merits some comment in the
Discussion.
The method of analysis is described. However as I am not familiar with the sROC
linear regression method (Moses and Littenberg) or hierarchical modelling of
ROC curves, the appropriateness of the method probably needs comment by a
statistician.
Results
The results of the search are described clearly. The relationship between study
quality and rectal bleeding is described in some detail as is the difference in the
relationship between rectal bleeding and cancer and the relationship between
rectal bleeding and polyps. Similarly detailed results are presented for weight
loss.
Discussion
• This is reasonable although the authors should comment on the interpretation
of the findings in relation to whether symptoms are recorded in patients
presenting in primary care / first contact settings and symptoms recorded in
referred patients.
• The high degree of discrepancy in data extraction from papers merits some
comment.
• There is a very recent systematic review that could be referred to in the
discussion.
[Shapley M. et al Positive predictive values of #5% in primary care for cancer:
systematic review BJGP September 2010]
Minor essential revisions
Some odd typographical errors
In Method section of Abstract:
“to provide to provide a 2x2 table”
Reference 28:
“du Toit J, Hamilton W, Barraclough K, du Toit J, Hamilton W, Barraclough K.
Risk in
primary care of colorectal cancer from new onset rectal bleeding:”
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
Statistical review: Yes, but I do not feel adequately qualified to assess the
statistics.
Declaration of competing interests:
I declare that I have no competing interests