Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Heritability and polygenic predictionIn the EUR sample, the SNP-based heritability (h 2 SNP ) (that is, the proportion of variance in liability attributable to all measured SNPs)

Purpose Although breast cancer is a growing health problem in sub-Saharan Africa, reasons for its increased occurrence remain unclear. Methods We reviewed published literature to determine the magnitude of the increase in breast cancer, associated risk factors (including for breast cancer subtypes), and ways to reduce incidence and mortality. Results Some of the increased breast cancer occurrence likely reflects that women are living longer and adopting lifestyles that favor higher incidence rates. However, a greater proportion of breast cancers occur among premenopausal women as compared to elsewhere, which may reflect unique risk factors. Breast cancers diagnosed among African women reportedly include a disproportionate number of poor prognosis tumors, including hormone receptor negative, triple negative and core basal phenotype tumors. However, it is unclear how lack of standardized methods for tissue collection, fixation and classification contribute to these rates. Given appropriate classifications, it will be of interest to compare rates with other populations and to identify risk factors that relate to specific tumor subtypes. This includes not only risk factors that have been recognized in other populations but some that may play unique roles among African women, such as genetic factors, microbiomata, xenoestrogens, hair relaxers and skin lighteners. Conclusions With limited opportunities for effective treatment, a focus is needed on identifying etiologic factors that may be amenable to intervention. It will also be essential to understand reasons why women delay seeking care after the onset of symptoms and for there to be educational campaigns about the importance of early detection.

Dual stain cytology showed good risk stratification for all HPV-positive women and for HPV-positive women with normal cytology. Additional follow-up is needed to determine how long dual stain negative women remain at low risk of precancer.