High Incidence of Triple-negative Tumors in Sub-saharan Africa: a Prospective Study of Breast Cancer Characteristics and Risk Factors in Malian Women Seen in a Bamako University Hospital

Objective: Few studies have been conducted on breast cancer in Sub-Saharan Africa and their results have been suspected to be impaired by artefacts. This prospective study was designed to determine tumor and patient characteristics in Mali with control of each methodological step. These data are necessary to define breast cancer treatment guidelines in this country.

Methods: Clinical and tumor characteristics and known risk factors were obtained in a consecutive series of 114 patients. Each technical step for the determination of tumor characteristics [histology, TNM, grade, estrogen (ER) and progesterone receptors (PR), HER2, and Ki67] was controlled.

Results: Patients had a mean age of 46 years. Most tumors were invasive ductal carcinomas (94%), T3-T4 (90%) with positive nodes (91%), grade III (78%), and ER (61%) and PR (72%) negative. HER2 was overexpressed in 18% of cases. The triple-negative subgroup represented 46%, displaying a particularly aggressive pattern (90% grade III; 88% Ki67 >20%).

Conclusion: This study demonstrates the high incidence of aggressive triple-negative tumors in Mali. Apart from a higher prevalence of premenopausal women, no significant difference in risk factors was observed between triple-negative tumors and other tumors. The hormonal therapy systematically prescribed therefore needs to be revised in light of this study.