Review for 10.1186/s12876-019-0996-y (2019)

Reviewer ’s report  
 
Title: Can the rate and location  of Sessile Serrated Polyps be Part of Colorectal Cancer Disparity 
in African Americans?  
 
Version: 0 Date: 20 Jan 2019  
 
Reviewer: Mingyang Song  
 
Reviewer's report:  
 
The study assessed the clinicopathological features of sessile serrated adenoma/polyps (SSA/Ps) 
among 225 African American (AA) patients identified in an institutional database. The study 
found a higher prevalence of SSA/Ps (2.5%) than what has been reported in the literature (~1%). 
Also, in contrast to previous findings that SSA/Ps are predominantly located in the proximal 
colon, the current study found that 76% of SSA/ Ps are located in the left colon and rectum. 
While the findings add new evidence on the potential racial difference in SSA/Ps, several 
methodological and analytical issues may be considered to further strengthen the paper.  
1. Although the primary aim of t he study is to assess the SSA/P characteristics among AAs, 
without data on other ethnic groups, it is hard to infer any racial differences based on the 
absolute data in AAs only. Therefore, the authors may consider presenting the data in all 
ethnic groups and formally test the differences across clinicopathological features (eg, by 
subsite, histology).  
 
2. The predominance of SSA/P in the left colon/rectum is striking and contrasts to the 
literature. In addition to presenting the data for other ethnic groups  as commented above, 
it would be good to provide the distribution data for each specific sublocation (as 
presented in Figure 2) for all analyses. Also, the notion of "rectal and rectosigmoid" in 
the abstract is confusing, because the left -sided lesions als o included those in the 
descending colon.  
 
3. As discussed by the authors, the 2.5% prevalence of SSA/Ps is not really comparable to 
the literature, which is largely based on the screening colonoscopies. Thus, to facilitate 
the comparison, it would be good to present the prevalence among screening 
colonoscopies only.  
 
4. In the discussion, the % of synchronous lesions was mentioned, but the reviewer couldn't 
find any such data in the results.  
 
5. Other minor suggestions:  
a. Table 1 includes clinicopathological  features rather than just demographic factors, as 
suggested by the title.  
b. Tables 2 -4: it would be good to add an open row "indications for colonoscopy" above 
each of the specific indications.  
a. Some recent references may be considered to add: a recent  meta -analysis on racial 
difference in prevalence of CRC precursor lesions by Thomas Imperiale, eta al in 
Gastroenterology and comprehensive risk factor profiling of conventional adenomas and SSA/Ps 
by Xiaosheng He, et al in Gastroenterology.  
Are the methods appropriate and well d escribed?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
No 
 
Are the conclusions drawn adequately  supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Unable to assess  
 
Are you able to assess any statistics in the manuscript or would you recommend an  
additional statistical review?  
If an additional statistical review is r ecommended, please specify what aspects require further  
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
Declaration of competing  interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, fees, funding, or salary from an  
organisation that may in any way gain or lose financially fro m the publication of this  
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation that may in any way gain or lose  
financially from the publication of this manuscript, either now or in the future?  
 
3. Do you hold or a re you currently applying for any patents relating to the content of the  
manuscript?  
 
4. Have you received reimbursements, fees, funding, or salary from an organization that 
holds  or has applied for patents relating to the content of the manuscript?  
 
5. Do you have any other financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have no competing interests' 
below.  If your reply is y es to any, please give details below.  
 
I declare that I have no competing interests  
 
I agree to the open peer review policy of the journal. I understand that my name will be included  
on my report to the authors and, if the manuscript is accepted for publicat ion, my named report  
including any attachments I upload will be posted on the website along with the authors'  
responses. I agree for my report to be made available under an Open Access Creative Commons  
CC-BY license ( http://creativecommons.org/licenses/by/ 4.0/). I understand that any comments  
which I do not wish to be included in my named report can be included as confidential comments  
to the editors, which will not be published.  
 
I agree to the open peer review policy of the journal