Abstract A12: Ethnic differences in the clinical and pathological characteristics of breast cancer among Kenyan women

Abstract

Abstract Background: Breast cancer is the most common female malignancy worldwide. The effect of race and ethnicity on breast cancer has been the subject of much investigation. However, there are no published data from specific regions of sub-Saharan Africa with regards to the ethnic distribution of breast cancer and its subtypes. Objective: To investigate the differences in clinical and pathological characteristics of breast cancer in three major ethno-cultural groupings (Bantus, Nilotes and Cushites) in Kenya. Methods: A nationwide prospective study involving 15 public, faith-based and private institutions, which recruited patients with pathologically confirmed breast cancer between March 2012 and May 2015, was conducted. Relevant socio-demographic, clinical, reproductive and known breast cancer risk factor data were collected using a standardized questionnaire. Central pathology review and immunohistochemistry of all breast cancer tissue were done at Aga Khan University Hospital Nairobi. Proportions, chi-square tests, and logistic regression were used in the analysis of data. Results: Among the 867 female study participants with malignant breast tumor, 675 (77.8%) were Bantus, 148 (17.0%) were Nilotes, 20 (2.4%) were Cushites, and 24 (2.8%) were patients of mixed ethnicity. Bantus were more likely than the other three ethnic groups to fall within the 40-49 year age group (32 vs 19, 15, and 25% respectively, p=0.002), more likely to have at most secondary education (27.6 vs 17.6, 0, and 16.7%, p=0.0003), and more likely to be farmers (33.9 vs 19.6, 0.0, and 16.7%, p<0.0001). The majority of the study population overall was overweight or obese. When limited to Bantus and Nilotes only, Bantus were significantly more likely to be overweight than Nilotes (42.0 vs 29.9%, p=0.04). After adjusting for age, Nilotes seemed more likely to present with larger tumors and less likely to present with lymph node metastasis (OR: 0.39, 95% CI: 0.24-0.65), extra nodal extension (OR: 0.42, 95% CI: 0.23-0.75), and lymphovascular invasion (OR: 0.67, 95% CI: 0.47-0.97). The data suggest that Nilotes may be less likely to have ER positive cancers and more likely to have HER2+ cancers, though these associations were not statistically significant. Conclusion: The differences observed for some of the clinical and pathologic features of Breast Cancer among the three distinct ethnic groups in Kenya could be multifactorial and attributable to socio economic indicators, lifestyle factors and probable genetic variations. The association of specific measurements and biomarkers of obesity from Breast cancer patients among the ethnic Kenyan population and the association of serum estradiol concentrations with ethnicity and breast cancer subtypes are areas of future research. Further research to explore the BC incidence among the ethnic groups may provide insight into yet unexplored risk factors and etiology of breast cancer. Citation Format: Shahin Sayed, Zahir Moloo, Ronald Wasike, Asim Jamal, Peter Bird, Maya Palakal, Gretchen Gierach, Dhiren Govender, Mansoor Saleh. Ethnic differences in the clinical and pathological characteristics of breast cancer among Kenyan women [abstract]. In: Proceedings of the AACR International Conference: New Frontiers in Cancer Research; 2017 Jan 18-22; Cape Town, South Africa. Philadelphia (PA): AACR; Cancer Res 2017;77(22 Suppl):Abstract nr A12.