**3. Types of breast cancer**

These are often obtained from clinical, histopathological and genomic diagnoses. Availability and accessibility of these are, however, varying in sub-Saharan Africa. This had affected presentation, reportage, early screening and diagnosis and treatment of breast cancer in the region. In many countries, breast cancer is still commonly confirmed by histology (85%); and 6% cytological confirmed; while 9% were clinically confirmed in many sub-Saharan African countries [11]. Fine needle aspiration (FNAC) and biopsy remain the commonly reported means of diagnosis; as it stands at 60% and 37.9%, respectively in Ethiopia [21].

About half (52.5%) of all suspicious breast lesions have been reported to be malignant; with 36% being benign conditions in some African populations [5]. Invasive ductal cancers appear to be the commonest among African populations accounting for more than half of all reported breast cancers [9, 17–19, 21]. This is congruent with globally reported histological type reported globally; which has been reported to be 40–80% [7]. It ranges between 55.3% in Southern Ethiopia and 84.2% in Kenya [18, 21]. Tumor behavior reported includes moderately differentiated in 31.7% of cases and poorly differentiated in 27.7% of cases in Southern Ethiopia. Only 13.6% were reported to be well-differentiated among Ethiopian patients [21].

Molecularly, BRACA 1 and BRAC 2 remains the commonest molecular gene for breast cancer in African populations. Each accounts for 5.6%, respectively, in sub-Saharan Africa the populations. Other reported genes include ATM (1.5%), PALB2 (1%), BARD1 (0.5%), CDHI (0.5%) and TP53 (0.5%) [26]. This is in line with the global commonly reported genes of 45–87% of BRACA 1, and 50–85% for BRACA 2 [7]. Novel variants of these genes have been reported to predominate in certain sub-Saharan African regions. This includes the PIK3CA genes and the TP53 genes; which account for 39.09% and 12.78%, respectively in Burkina Faso [23].

Most cases of breast cancer in the last decade have presented with unilaterally located left breast cancer across sub-Saharan Africa [9, 16, 19, 21, 27]. The highest prevalence of bilateral breast cancer was reported at 8% [95%CI: 6, 12] in Nigeria [16]. Country-specific prevalence of left breast cancer has been reported across the sub-region. For example, Gabretsadik A et al. and Kramer and Colleagues; Ouedrago SY et al. and Uyisenga JP et al. reported that 54%, 52.2%, 51% and 50% of most breast cancer cases are on the left breast among Southern Ethiopian, Rwanda, South African patients and Burkinabe patients [19, 21, 23, 27]. Balekouzou A et al. reported that the left breast is more commonly affected compared the right (12% versus 4%, respectively) among patients in Central African Republic [9].
