The African Breast Cancer - Disparities in Outcomes (ABC-DO) study is a multi-country sub-Saharan African study of determinants of breast cancer outcomes. The number of women diagnosed with breast cancer per year is rising rapidly in Africa, and the consequences of poor survival are worsened by the young age of women affected. ABC-DO will recruit women from four public hospitals in Nigeria, Uganda, South Africa, and Namibia and examine the full journey of breast cancer patients, both pre- and post-diagnosis, in order to identify modifiable determinants of survival, to be able to prevent avoidable deaths from breast cancer in African women.