Global Authorship Patterns in Phase III Solid-Tumor Trials Presented at the ASCO Annual Meeting, 2015-2025

Purpose Authorship of phase III oncology trials reflects broader patterns of scientific leadership, including access to resources, research infrastructure, and global participation. However, how these factors intersect with gender over time remains incompletely characterized. We evaluated trends in authorship across phase III solid-tumor trials presented at the ASCO Annual Meeting from 2015 to 2025. Methods We conducted a repeated cross-sectional study of phase III solid-tumor abstracts presented at ASCO (2015-2025). Author gender was assigned using a multistep approach based on publicly available data. Outcomes included authorship by role (first v senior), tumor track, funding source, trial-origin geographic region, and trial-origin World Bank income group. Multivariable logistic regression identified factors associated with female authorship. Results Among 1,517 abstracts (3,034 authorships), 27.9% of authors were women. Female authorship increased from 24.9% in 2015-2020 to 30.0% in 2021-2025 ( P = .002). Women were more likely to be first than senior authors (54.7% v 45.3%, P = .002) and were less likely to hold senior authorship overall (adjusted odds ratio [OR], 0.76, 95% CI 0.65-0.90; P = .001). Temporal gains were driven by increased female senior authorship (OR, 1.55 [95% CI, 1.20 to 1.99]; P = .001). Female authorship was lower in several tumor types and in East Asia and Pacific versus North America (OR, 0.65 [95% CI, 0.48 to 0.87]; P = .003). Funding and income group were not associated with female authorship. Conclusion Women remain underrepresented in phase III oncology trial authorship, particularly in senior roles and across certain tumor types and regions, suggesting persistent gaps in authorship representation that may reflect broader structural barriers.