Molecular Biology of Breast Cancer in the Horn of Africa: Case Series—A Pilot Study of Breast Cancer from Eritrea

Abstract

Background. Recently, gene expression profiling and its surrogate immunohistochemistry (IHC) markers classified breast cancer into four distinct molecular subtypes, which have different prognoses, targeted therapies, and/or clinical outcomes. Objective. To conduct a preliminary study, to correlate the clinical pathological profiles and taxonomy of molecular subtypes of breast cancer in Eritrea, in the Horn of Africa. Design. Review of pathology reports from Jan. 1 to Nov. 30, 2009, provided 22 cases of microscopically confirmed invasive breast carcinoma that were evaluable for histology and IHC (ER, PR, HER2, and Cytokeratin 5/6). Result. Twenty patients were female and most of them (68%) were under 50 years at presentation. 90% were invasive invasive carcinoma of no special type and were histological grade 3. The molecular subtypes were luminal A (55%), luminal B (5%), HER2 (5%), basal-like (10%), and unclassified (25%). Triple negative carcinoma (basal-like and unclassified combined) was 35%, mostly (71%) in women under 50 years with grade 3 tumours. Conclusion. Breast carcinoma in Eritrean women presents at a younger age and with a high histologic grade. The two predominant molecular subtypes are luminal A and triple negative. Determining the molecular subtype using surrogate IHC markers has important treatment and prognostic implications for Eritrean women with breast cancer.

Comparison of Receptor-Defined Breast Cancer Subtypes Between German and Sudanese Women: A Facility-Based Cohort Study

“…Recent studies, however, have shown relatively low proportions of ER- and PR-negative BC: Ethiopia (34.7%), 11 South Africa (37%), 12 Sudan (36%), 13 Nigeria (35%), 14 and Eritrea (32%). 15 These recent findings are comparable with that from African American premenopausal women in the Carolina Breast Cancer Study (39%). 16 A recent systematic review and meta-analysis in Africa showed that the proportion of ER- and PR-negative and human epidermal growth factor receptor 2 (HER2)–positive BC in Africa is highly variable.…”

“…We noted a higher proportion of ER- and PR-negative BCs compared with recently published studies in Africa. 11 - 15 , 29 , 30 Publications that directly compared African and white patients show differences in ER status of various magnitudes. Similar to our findings, the result of a higher rate of receptor-negative BC was reported in Tanzania compared with Italian patients 23 ; however, the investigation that compared Sudanese women (from a single institution in Khartoum) with Italian women (from Milan, Italy) 13 and, similarly, Ghanaian women with Norwegian women reported minimal difference.…”

“…This finding is similar to that noted for Nigerian women, 6 , 14 other East African reports (Uganda and Tanzania), 23 , 34 and North Africa (Egypt). 35 Many studies have reported that TNBCs are the dominant phenotype in native African women 6 , 15 , 34 and African Americans compared with white women. 16 , 36 Our findings support the existing reports, 6 , 23 , 34 although a previous single study from Sudan 13 has reported much lower rates of ER- and PR-negative BC than our current study.…”