Burden and trends in cancers of the breast in sub-Saharan Africa

Despite breast cancer (BC) being the most common cancer in sub-Saharan Africa (SSA), there is insufficient evidence on its temporal trends across the continent, and on reasons for differences in the cancer burden observed. This thesis sets out to describe the BC burden and trends in SSA. Specifically, it aims at describing incidence trends and survival patterns across SSA using population-level cancer registry data from the African Cancer Registry Network and to summarise the aetiologic research from SSA. The temporal trends in BC incidence rates in women from 10 SSA countries over the last 15 years are described. There are rising incidence rates in all registries; however, these temporal trends are of different magnitudes. Trends in registries with the longest temporal data show rising incidence rates across successive birth cohorts of women aged 45+. Reasons for the differences observed in the incidence trends are explored. A systematic review was carried out summarising the evidence from SSA on reproductive, anthropometric, and lifestyle risk factors. The associations observed are similar to Western studies, however, quality aetiological research has been conducted in less than 75% of SSA countries. The population-level prevalence of these risk factors are described. The short-term relative survival outcomes of women diagnosed with BC across 12 African countries are also estimated. There are large survival differences across the continent. Late-stage at diagnosis and limited access to quality care are drivers of survival differences. More than two-thirds of women present at stages III/IV, and approximately 50% of women with non-metastatic BC receive inadequate or no cancer-directed therapy. However, there are challenges of incomplete records and high rates of loss to follow-up. In conclusion, the BC burden is rising in SSA. It is imperative to improve timeliness of diagnosis, access to care, aetiologic research, and the quality of cancer surveillance.