Ethnicity and breast cancer characteristics in Kenya
There are no published data from specific regions of sub-Saharan Africa describing the clinical and pathological characteristics and molecular subtypes of invasive breast cancer by ethnic group. The purpose of this study was to investigate these characteristics among the three major ethno-cultural groupings in Kenya.
The study included women with pathologically confirmed breast cancer diagnosed between March 2012 and May 2015 at 11 hospitals throughout Kenya. Sociodemographic, clinical, and reproductive data were collected by questionnaire, and pathology review and immunohistochemistry were performed centrally.
The 846 cases included 661 Bantus (78.1%), 143 Nilotes (16.9%), 19 Cushites (2.3%), and 23 patients of mixed ethnicity (2.7%). In analyses comparing the two major ethnic groups, Bantus were more educated, more overweight, had an older age at first birth, and had a younger age at menopause than Nilotes (p < 0.05 for all comparisons). In analyses restricted to definitive surgery specimens, there were no statistically significant differences in tumor characteristics or molecular subtypes by ethnicity, although the Nilote tumors tended to be larger (OR for ≥ 5 cm vs. < 2 cm: 3.86, 95% CI 0.77, 19.30) and were somewhat more likely to be HER2 enriched (OR for HER2 enriched vs. Luminal A/B: 1.41, 95% CI 0.79, 2.49).
This case series showed no significant differences in breast cancer tumor characteristics or molecular subtypes, but significant differences in sociodemographic characteristics and reproductive factors, among the three major ethnic groups in Kenya. We suggest further evaluation of ethnic differences in breast cancer throughout the genetically and culturally diverse populations of sub-Saharan Africa.
KeywordsBreast cancer Kenya Ethnic differences Ethnicity Sub-Saharan Africa
The authors would like to thank GSK-ERI for funding, administrative staff of Aga Khan University, all participating institutions, and all nurses and technologists at the participating sites. In addition, the authors would like to thank Angela Mutuku and Gaylord Mwangi (AKU) for their assistance in formatting and assistance with the illustrations in this manuscript. This study was supported in part by the Intramural Research Program of the Division of Cancer Epidemiology and Genetics of the U.S. National Cancer Institute.
SS, ZM, and MS conceived and carried out the study; SS, ZM, PO, and SG carried out the centralized laboratory work; IA, CK, TH, and SM performed data management; TH, SM, CK, GLG, SF, MM, and MP analyzed the data; RW, PB, RO, FWN, AJ, SVP, SV, RC, AZ, MM, BB, CM, OAS, AM, AG, JG, JK, RN, RN, IM, JOO, DOR, EBM, and IA contributed to data collection and/or data management. All authors were involved in writing/reviewing the manuscript. All authors gave final approval of the submitted version of the manuscript.
Compliance with ethical standards
Conflict of interest
All the authors have no competing interest to declare.
Aga Khan University Hospital, Nairobi Research and Ethics Committee (REF: 2011/25), and the institutional review boards of all participating health facilities approved the study. Written informed consent was obtained from all study participants.
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