Abstract P3-12-17: Breast cancer treatment related survival gains in the African breast cancer - Disparities in outcomes study

Abstract Background: Breast cancer (BC) survival in Low and Middle Income Countries (LMICs), and particularly Sub Saharan Africa (SSA), is low and incidence rates are increasing. Accordingly, an almost 90% increase in annual BC mortality is projected to occur until 2040. The WHO Breast Cancer Global Initiative named comprehensive breast cancer treatment as one of three main pillars to reduce BC mortality. Here, we present the urgently needed up-to-date benchmark estimates of treatment effects on BC survival in SSA using data from the African Breast Cancer Disparities in Outcomes (ABC-DO) study.Methods: Since 2014 the hospital-recruited ABC-DO cohort follows-up women diagnosed with BC in five SSA countries. Socio-demographic, diagnostic, treatment and mortality data were obtained from medical records and via three-monthly follow-up calls with the patient. Cox proportional hazard models were fitted to estimate 5-year overall survival related to treatment initiation (surgery or systemic therapy) and treatment completion as time varying variates (surgery and systemic therapy completed) stratified by country and ethnicity and separate for localised and regional tumours. All models were adjusted for age, tumour grade, tumour size, node positivity, HIV status, and socioeconomic status. Results: Of 1699 ABC-DO women with invasive non-metastatic BC, 89% initiated BC treatment (from 72% in Nigeria to 100% in South African white women). Potentially curative treatment (surgery plus systemic therapy) was initiated by 63%, 22% initiated systemic treatment and 5 % only surgery. Initiated systemic therapy was completed by 49% of patients (from 16% in Nigeria to 70 % in South African black women). Median time to first treatment was 1.4 (IQR: 0.8–3) months and differed between countries (from 1.1 (0.6–1.7) in Namibian non-black to 3 (1.5–4.3) in Uganda). After 5 years, 49% (0.44 (CI: 0.31 – 0.62) ) of women initiating any treatment and 59% (0.39 (0.27 – 0.56) of women receiving surgery and initiating systemic treatment were still alive compared to 20% of women receiving no treatment. Conclusion: Timely and comprehensive BC treatment are needed to increase the very low survival rates in SSA. Citation Format: Milena Foerster, Eva Kantelhardt, MD, Pauline Boucheron, Isabel dos-Santos-Silva, PhD, Valerie McCormack, the ABC-DO study team. Breast cancer treatment related survival gains in the African breast cancer - Disparities in outcomes study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-12-17.