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:30 November 2010
Reviewer: Floris Van de Laar
Reviewer's report:
Dear editor,
Thank you for giving me the opportunity to review the paper ‘Most bowel cancer
symptoms do not indicate colorectal cancer and polyps: a systematic review’.
This is a highly relevant topic that relates directly to everyday practice of people
who work in primary care. The paper is well written and has, in general, a sound
methodology. Nevertheless, I have some comments/questions which I would like
to be addressed.
Major
1)One of the conclusions is that weight loss is a predictor for colon cancer and
indicates the need for colonoscopy. I doubt that any doctor will, after reading this
paper, refer every patient with weight loss for colonoscopy, at least not as the
first diagnostic step. Most (if not all) data is derived from selected patient groups
in which at least a part of them already had symptoms (probably gastrointestinal).
Probably a better conclusion would be that colonoscopy is indicated in patients
with weight loss AND a high prior probability. But then, when do we have a high
probability in primary care when we do not have good predictive signs and
symptoms? Catch 22.
2)In real life, the decision whether or not to refer someone for colonoscopy is a
subtle mix of items from history, physical examination, specific patient
characteristics (age, family etc) and ‘gut feeling’ of the doctor. In this review the
signs and symptoms are investigate more or less in isolation. I do not see how
statistics do or may account for this.
3)In their final conclusion authors suggest that we should focus on screening
programs rather than ‘attempting to identify cancers and polyps through
investigating people with symptoms’. I do not agree with this conclusions for two
reasons. First I miss the point that mass screening is better than current practice
in which we try to identify people with (pre)cancer as early as possible. Second,
people will keep going to their doctors with signs and symptoms that might relate
to serious disease. Referring everyone for colonoscopy is simply not an option.
4)The discussion section could be improved if authors elaborate a little more on
the comparison with existing reviews (ref 76 & 77). Please note that a third
systematic review was published last year on rectal bleeding and the value of
additional signs (Olde Bekkink et al. Br J Cancer 2010;102:48-58).
Minor
5)The authors excluded studies that did not differentiate between cancers and
polyps. This decision might seem logical at first sight, but there are arguments to
include those studies and to have an (additional) analysis with studies that don’t
differentiate between cancer and polyps. Both polyps and (of course) cancer are
a good reason to refer for colonoscopy. In fact, a (suspected) polyp is even a
better reason because for polyps colonoscopy is both a diagnostic and a
therapeutic procedure. Therefore most physicians will be more interested in the
question ‘is colonoscopy of added value in this patient’ rather than ‘does this
patient have cancer / polyp’. I don’t think authors should redo their analyses
(maybe in future update?) but they might give it some thought in the discussion
section.
Floris van de Laar
Level of interest: An article of importance in its field
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