Review for 10.1186/1471-230X-9-37 (2009)

Reviewer's report
Title:Polymorphism in COX-2 modifies the inverse association between
Helicobacter pylori seropositivity and esophageal squamous cell carcinoma risk
in Taiwan: a case control study
Version: 1Date:28 January 2009
Reviewer: Farhad Islami
Reviewer's report:
This is an interesting article that reports on the association of Helicobacter pylori
infection and polymorphisms in Cox-2, and interaction of these factors, with risk
of esophageal squamous cell carcinoma (ESCC) in a Taiwanese population. The
study seems to be well-designed, data are clearly presented, and the manuscript
is well-structured. Overall, the manuscript is easily readable. However, the
wording in several sentences could be improved. Overall, this study addresses
an interesting issue in ESCC carcinogenesis.
Some minor essential revisions are required:
1. In the first sentence of the Background section, other high incidence areas
should be mentioned (such as central Asia and southern and eastern Africa:
Parkin et al 2005). Otherwise, the sentence should be changed to something like:
the incidence is high in some geographical areas, such as certain parts of China.
A more recent reference should also be used for this sentence.
2. I wonder if the controls were healthy people who underwent routine physical
examinations or they were outpatients who referred to a clinic because a health
problem. Although polymorphism in COX-2 is not likely to be related to control
selection method, the authors should add a few sentences to the Methods to
describe the control selection process.
3. In “polytomous logistics regression was applied in the multivariate analysis to
determine the risk of contacting the two defined cancer groups”, the word
“contacting” was not clear to me, as well as “contracting” in “an increased risk of
contracting ESCC” (Abstract).
4. Were the P-values one-sided or two-sided? This should be mentioned in the
last sentence of the Methods.
3. One row in Table 4 is redundant. In addition, p for H-W3 should be changed to
p for H-W2.
4. Numbers beginning a sentence must be spelled.
5. There are some typos in the text, for example: low-third ESCC, once time per
week, remain blood cells.
6. Some words should also be changed, for example: pathologically to
histopathologically, computer tomography to computed tomography or
computerized tomography, gastroendoscope to gastroscopy or upper
gastrointestinal endoscopy or another relevant term.
7. In the following sentence “It means that H. pylori seropositivity has an inverse
association with ESCC risk and it was modified by COX-2 polymorphism,
especially in the lower third of the esophagus, the anatomy close to the stomach
where H. pylori presented”, the first phrase seems to be a little bit strong; I would
suggest changing “means” to “suggests”. In addition, “was” should be changes to
“is”. The importance of anatomical proximity to the source of H. Pylori infection is
not clear to me. The fact that the lower third of esophagus, compared to upper
esophagus, is more exposed to acid (in case of acid reflux) may be more
important.
8. Finally, in footnotes of Tables 2 to 4, the authors should provide some
information about the covariates (if there were continuous, or describe the
categories). If categories in Table 1 were used, the authors could only state this
in each footnote.
Level of interest: An article of importance in its field
Quality of written English: Needs some language corrections before being
published
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
I declare that I have no competing interests.