Abstract 7104: Variation in breast cancer molecular sub-types prevalence among ethnic groups within Ghana and implication for tumor biologic studies among African-Americans

Abstract

Abstract Background: Triple negative breast cancer (TNBC) is most prevalent in women with Western sub-Saharan African ancestry, including African Americans (AAs) and continental African women. This similarity in risk has been shown to be due in part to the shared genetic ancestry resulting from the trans-Atlantic slave trade. To understand the role of genetic African ancestry in the risk and tumor biology of TNBC in AAs, we established a research collaboration in Ghana (West African, WA), Precision Medicine for Aggressive Breast Cancers (PMABC), to access WA female patients and their tumors for comparative studies with AAs. A principal goal of the PMABC study is to take a more inclusive approach to broadly capture the epidemiologic and tumor biologic characteristics of breast cancer within Ghana. Methods: To achieve this objective, PMABC is based on a collaborative network of six Ghanaian institution, representing the entire country, and in this first analysis, we describe how patient characteristics, including ethnicity, are related to molecular subtypes of breast cancer in this prospectively collected cohort. We used multinomial logistic regression to evaluate the associations between the molecular breast cancer sub-types (Luminal A, Luminal B, HER2+, TNBC) and patient characteristics. Results: Sociodemographic data, clinical/pathologic characteristics, and biological samples were collected from a total of 690 consented cases. Among these women the mean age (SD) was 51.37 (13.5) years and mean BMI was 27.9. Importantly, nine different ethnicities were captured in the sample, and 79% of the patients belonged to one of the four main Ghanaian ethnic groups: Akan (Southern, n=352, 51%), Dagomba (Northern, n=36, 5.2%), Ewe (Southeastern, n=93, 13.5%), and Ga (Southwestern, n=61, 8.8%). 38.4% of all the cases were TNBC. There was a significant difference in the risk of developing TNBC among the different ethnic groups; in particular, the Ga ethnic group had the lowest TNBC proportion at 23.7%. Relative to the Akan TNBC prevalence (42.8%) and the Luminal A subtype, the Ga had a 61% decreased risk of TNBC (odds ratio =0.39; p=0.007). Additionally, being menopausal was associated with a decreased risk of developing Luminal B (p=0.029), HER2+ (p=0.018), and TNBC (p=0.027), relative to luminal A subtype. There was also a significant decrease in the age of diagnosis for those with the Luminal B (p=0.008) and HER2+ (p=0.025) subtypes when compared with those who had Luminal A subtype. Conclusion: These findings are among the first to indicate significantly different risk of TNBC among the geographically diverse ethnicities within Ghana, and they suggest the need for a more refined sub-continental genetic ancestry analysis to effectively determine the impact of genetic African ancestry on the biology of both WA and AA breast cancer. Citation Format: Moses A. Dokurugu, Moses Kamita, Sylvester Antwi, Rose Dampson, Patrick K. Akakpo, Harriet Larrious-Lartey, Valerie Ofori Aboah, Foster Amponsah, Josephine Nsaful, Michael Nortey, Kwabena Agbedinu, Samuel Mensah, Mohammed Sheriff, Nelson Affram, Ijeoma Aja, Alex Mremi, Theresia Mwakyembe, Mohammed Bharmal, Veneranda Nyarko, Ali Haythem, Eleanor Walker, Jessica Bensenhaver, Albert Levin, Evelyn M. Jiagge. Variation in breast cancer molecular sub-types prevalence among ethnic groups within Ghana and implication for tumor biologic studies among African-Americans [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7104.