The impact of HIV infection on overall survival among women with stage IV breast cancer in South Africa.

Abstract

6559 Background: Advanced stage at breast cancer (BC) diagnosis is common in sub-Saharan Africa. In public hospitals across South Africa (SA), 10-15% of women present with metastatic BC, compared to <5% in the U.S., and 20% of new BCs are diagnosed in women living with HIV (WLWH). We evaluated the impact of HIV on overall survival (OS) among women with stage IV BC, which is associated with a poor prognosis in SA. Methods: We conducted a prospective cohort study of women diagnosed with stage IV BC between February 2, 2015 and September 18, 2019 at six public hospitals in SA. Baseline characteristics were compared by HIV status and multivariate Cox regression models were used to estimate the effect of HIV on OS. Results: Among 550 eligible women, 147 (26.7%) were WLWH. Compared to HIV-negative BC patients, WLWH were younger (median age 45 vs. 60 years, p<0.001), predominantly black (95.9% vs. 77.9%, p<0.001), and more likely to have hormone receptor-negative BC (32.7% vs. 22.6%, p=0.016). HER2 tumor status did not differ by HIV status (25.3% HER2 positive overall), and Ki67 index was not increased among WLWH (57.1% Ki67 > 20 overall). Receipt of systemic anti-cancer therapy did not differ by HIV status (80.9% treated overall) and most women were treated with anthracycline (55.5%). HIV status was not associated with OS (Hazard Ratio (HR)=1.13, 95% confidence interval (CI)=0.89-1.44) (Table). In an exploratory subgroup analysis, WLWH and hormone receptor-negative BC had shorter OS compared to HIV-negative women (1-year OS: 27.1% vs. 48.8%, p=0.003; HR=1.94, 95% CI=1.27-2.94), which was not observed for hormone receptor-positive BC. Results were unchanged when analysis was restricted to black women only. Conclusions: HIV status was not associated with worse OS in women with stage IV BC in SA and cannot account for the poor survival in our cohort. Subgroup analysis revealed that WLWH with hormone receptor-negative BC had worse OS; this differential effect of HIV on BC survival by hormone receptor status is a novel finding that warrants further investigation.[Table: see text]