Review for 10.1186/1471-230X-14-179 (2014)

Reviewer's report
Title:Occurence of Helicobacter pylori and Epstein-Barr virus infection in
endoscopic and gastric cancer patients from North Brazil
Version:2Date:1 March 2014
Reviewer: Ezequiel Fuentes-Panana
Reviewer's report:
In the study “Occurence of Helicobacter pylori and Epstein-Barr virus infection in
endoscopic and gastric cancer patients from North Brazil” submitted by Souza
CRT et al, the presence of H. pylori, the virulence factor CagA and EBV is
addressed in gastric samples derived from children (n = 64), which underwent
endoscopy of the upper GI tract, and in adult samples of gastric tumors (n = 125).
HP was detected by using the Christensen 2% urea medium, CagA by PCR and
EBV by EBER1 ISH. 11 children presented normal gastric mucosa, 53 some
level of gastritis and pathogen positivity was then contrasted against each
normal, gastritis and cancer and also against clinical and histological
characteristics. Several positive associations are found, although a multivariate
analysis only showed an increased risk to present moderate to severe gastritis if
infected by HP. CagA was positively associated to intestinal type gastric cancer
and lymph node metastasis. Only one pediatric patient was infected by EBV and
12 adults with cancer. The data as presented is marginally interesting because
HP association with gastric disease has been widely documented. Still, this is an
analysis of a significant number of samples that can be improved if tightly
presented and enriched with further analysis.
Major comments:
1. All comparisons against the normal mucosa group seem inadequate since the
average age of this group is 7 yo; similarly for comparisons between gastritis
(pediatric patients) and cancer (adults) groups. Only comparisons within the
same group are informative, and if the ORs and p´s are presented corrected by
age.
2. The chosen urease test to detect HP has low sensitivity and specificity and
should be complemented with another test, e.g. specimen staining and
histological examination.
3. The 9.6% of EBV positives tumor is about the average frequency found
wide-world. Were those positives enriched for specific histological patterns: e.g.
lymphoepithelioma or lace pattern?
4. EBV analysis in gastritis samples remains poorly studied. To find one positive
sample is interesting and to present a picture of the ISH would be very
informative. How many cells were infected? Were they epithelial or lymphoid? Is
there clinical data of that patient, e.g. the result correlated with mononucleosis
symptoms?
Minor comments
1. How the samples were obtained is not described, only the patients. How many
biopsies were taken for each pediatric patient? What regions of the stomach
were represented in the sample taken?
2. Explain the numbers in table 1. Many times those numbers do not add up to a
100%.
3. The article needs extensive correction of English grammar and style.
Level of interest: An article of importance in its field
Quality of written English: Not suitable for publication unless extensively edited
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