Reviewer ’s report  
 
Title: Breast Cancer in Ethiopia: Evidence for geographic difference in the distribution of 
molecular subtypes in Africa  
 
Version: 0 Date: 26 Nov 2017  
 
Reviewer: Saraswati Sukumar  
 
Reviewer's report:  
 
The authors report on a study conducted on the incidence and molecular types of breast cancer in 
Sub-Saharan  
Africa, and to compare the results to published work mainly from Western and Central Africa 
that show that breast cancer  occurs at younger ages, presents with aggressive features that 
include high -grade, advanced stage and triple -negative phenotype (negative for ER, PR and 
HER2). Data, though limited, does exist from East Africa including Ethiopia that shows that 
hormone receptor  negative tumors account for a lower proportion of all breast cancers compared 
to the rest of Africa. For example, of 352 cases (BMC Cancer. 2014 Nov 29;14:895), Yonas et al 
published that 65% were ER+. Similarly, nearly 70% were found to be ER+ in an other study 
(Newman, LA); similar results were reported on 186 women of Ethiopian origin living in the US 
(78% ER+, 22% ER -);Breast Cance r Res Treat. 2012 Oct;135(3):867 -73). No HER2 evaluation 
was reported.  In this paper, breast cancer patients (n=114; years 2012 -2015) were examined for 
ER, PR, Ki67 and HER2 receptor status using immunohistochemistry from tissue microarrays. In 
equivocal tumor samples, FISH was used for assessment of gene amplification and for 
confirmation in HER2 -enriched cases. They expressed the results using the St. Gallen model and 
found: Luminal A and B formed 66% of the cases, HER2 enriched 10%, and TNBC 23%. The 
manuscript is written well and data presented logically and confirms previous findings while 
reporting on the HER2 status as well.   
A major concern with this paper is the use of tissue microarrays to perform the studies.  ASCO 
guidelines state that sections  of multiple core biopsies should be used to accurately assess 
percent positive for the various markers.  In most other studies, whole sections of the surgical 
blocks are used to circumvent problems in cell numbers.  Were whole sections used first to 
deter mine the concordance in calls in a pilot before embarking on this study. How many 
epithelial cells were counted in order to deem them positive or negative?  How did FISH results 
look on the small 6 mm spots?  Since none of this data is presented it is not possible to assess 
accuracy.  
The second concern is that that the study is small n=114, and the results are at best, again 
interesting, but not reliable. The HER2 results are new, but the methods used make it difficult to 
interpret.   
Are the meth ods appropriate and well described?  
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 co nclusions 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:  
 
Acceptable  
 
Decla ration 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 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 are 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 f or 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'  
 
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