Equity in breast cancer research authorship: Country, gender, and income representation in phase III trials presented at the ASCO Annual Meeting (2015–2025).

11083 Background: Equitable representation in global oncology research is essential for scientific validity, generalizability, and ethical trial conduct. However, leadership in clinical research remains concentrated in high-income countries (HICs), with persistent gender inequities. We evaluated longitudinal trends in geographic, economic, and gender representation among authors of Phase III breast cancer trials presented at the ASCO Annual Meeting. Methods: We conducted a retrospective analysis of abstracts accepted to the ASCO Annual Meeting from 2015–2025 within breast cancer tracks, including metastatic and local/regional/adjuvant categories. Abstracts were identified using keyword searches for “phase” and included if they reported Phase III clinical trial data. For each eligible abstract, data were extracted for first and senior (last) authors, including institutional affiliation, country, World Bank region, and World Bank income classification. Author gender was assigned using a hierarchical approach incorporating culturally associated names, publicly available professional profiles, and genderize.io. Differences in authorship distribution by country were assessed using a univariate generalized linear model with country as a fixed effect. Results: Of 1,199 screened abstracts, 420 met inclusion criteria. Authorship was dominated by North America (44%) and Europe/Central Asia (40%), with representation from Latin America/Caribbean and Middle East/North Africa/Afghanistan/Pakistan each < 1%. The United States accounted for 40.7% of all authorship. East Asia representation increased from 2.8% (2015) to 19.1% (2025), driven by China, South Korea, and Japan. Country effect on authorship share was significant (F = 3.381, p = 0.001), while year was not (F = 0.000, p = 1.000), indicating persistent structural hierarchies. Overall, 93% of authors were affiliated with HICs, ~7% with upper-middle–income countries, and < 1% with lower-middle–income countries; no senior authors were from lower-middle–income countries. Gender distribution was 61.7% male and 37.7% female. Only Germany demonstrated female predominance in senior authorship among top contributing countries, while Japan exhibited 100% male senior authorship. Conclusions: Phase III breast cancer research presented at ASCO remains structurally concentrated in high-income countries with persistent geographic, economic, and gender inequities. Low- and middle-income countries remain largely excluded from academic leadership, and senior authorship remains male-dominated. These findings demonstrate enduring structural imbalances in global oncology research production and leadership, underscoring the need for equity-focused funding models, inclusive trial governance, and capacity-building research partnerships.