Meta-analysis finds 32% higher breast cancer mortality hazard for Indigenous women despite lower incidence

Breast cancer is the most common cancer diagnosed in women worldwide. Our understanding of the burden of breast cancer among Indigenous women remains limited due to limited availability of Indigenous data in global statistical databases. To address this concern, we systematically reviewed existing evidence of breast cancer incidence, mortality, and survival among Indigenous women by searching PubMed, Web of Science, CINAHL, and Embase using the terms "breast cancer," "incidence," "mortality," "survival," and "Indigenous peoples." A random-effects meta-analysis was performed to estimate the pooled adjusted hazard ratio (aHR). Overall, 61 studies from the United States (35), Australia (9), New Zealand (8), Canada (5), and Brazil (2), as well as one each from Peru and Colombia, were included in our analysis. Our findings revealed age-adjusted incidence rates of breast cancer ranging from 19.0 to 165.2 per 100,000 Indigenous women, compared to 21.5 to 190.4 per 100,000 non-Indigenous women, accompanied by a 32% higher hazard of mortality (aHR = 1.3; 95% confidence interval: 1.2-1.5). Pooled aHRs were 1.5 in Oceania and 1.1 in North America, and 1.4 and 1.2 for the years 2013-2017 and 2018-2023, respectively. Despite improvements over time and a lower overall incidence, Indigenous women have a higher hazard of mortality from breast cancer than their non-Indigenous counterparts. Continued efforts to enhance early detection and healthcare access are essential to improve the clinical outcomes of breast cancer among Indigenous women. Additional research targeting Africa, Asia, and Latin America will improve our understanding of the overall global burden of breast cancer.