Reviewer ’s report  
 
Title: Breast Cancer in Ethiopia: Evidence for ge ographic difference in the distribution of 
molecular subtypes in Africa  
 
Version: 0 Date: 27 Sep 2017  
 
Reviewer: Yinghao Su  
 
Reviewer's report:  
 
In this study a total of 114 cases of breast cancer from a single hospital in Ethiopia of Eastern 
Africa area were enrolled in analysis of molecular subtypes determined by IHC and FISH.  The 
study revealed that Luminal A subtype is the most common subtype, concordant with other study 
reports from Eastern African countries. This is different from West and central Africa where the 
hormone receptor negative tumors were reported to be the mos t common molecular subtypes. 
The author also found that Ethiopian breast cancer patients exhibit highly proliferative Luminal 
B tumors at young ages. The study methods such as tissue microarray, IHC, FISH, scoring and 
subtyping criteria are proper. The man uscript is generally well structured and written. The study 
results and limitations are clearly presented. There are a few critical concerns that need authors 
to address and major modifications are needed before accepted for publication.  
1. One of major co ncern is too small sample size from a single hospital with potential subject 
selection bias. Based on this study it is not acceptable to conclude that "Our findings suggest 
geographic variability in the distribution of the molecular subtypes of breast canc er in Africa 
and hence have important clinical and policy implications for breast cancer control and 
treatment in Ethiopia." Authors may overstate their findings. I would suggest authors to 
include other study results from Eastern African countries in the Table 4 (page 9) to 
strengthen this study. The conclusion sentence need to be modified.  
 
2. Another concern is the relatively high rate of missing clinicopathological data (histological 
type, grade and tumor stage), which further decreased statistical power  in this small sample 
size study. The results that "There were no statistically significant differences in tumor grade, 
histology, and stage between the molecular subtypes of breast cancer" (in Abstract) are not 
reliable. I think the missing histological t ype and grade data can be obtained through 
reviewing TMA slides (with HE staining) by a pathologist.  Other study results from Eastern 
African countries may also be considered to include as a meta -analysis, if applicable.  
 
3. Table 1 is not necessary. It c an be replaced by one sentence.  
 
4. Typos: Page 9, Lines 44, 45: "Luminal A (36%)" shall be (40%), "...represents 24%" shall be 
23%, based on the Table 4.  
African  countries 
(Burundi,Comoros,Djibouti,Eritrea,Ethiopia,Kenya,Madagascar,Malawi,Mauritius,Mayotte,Moz
ambique,Reunion,Rwanda,Seychelles,Somalia,Tanzania,Uganda,Zambia,Zimbabwe)  
Are the methods appropriate and well described?  
If not, please specify what is required in you r 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.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in  your comments to the authors.  
 
No 
 
Are you able to assess any statistics in the manuscript or would you recommend an  
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further  
assessment in  your comments to the editors.  
 
I recommend additional statistical review  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
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 from the publi cation 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 are you curr ently 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 yes 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 publication, my named rep ort 
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 understa nd 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