Reporting of sex-related data in landmark phase III solid tumor trials presented at ASCO 2025.

11088 Background: Sex-related differences may influence cancer biology, treatment efficacy, and toxicity. Although consideration of sex as a biologically relevant variable is increasingly encouraged in oncology research, the extent to which sex-specific information is visible at the time of initial presentation of practice-changing clinical trial results remains unclear. Methods: We conducted a cross-sectional review of phase III solid tumor trial abstracts enrolling mixed-sex populations presented at the ASCO Annual Meeting 2025. Plenary, oral, and rapid oral abstracts representing practice-changing studies across tumor types and treatment modalities were included. Abstracts were systematically assessed for reporting of sex distribution and for sex-stratified efficacy or toxicity outcomes. Results: Ten landmark phase III trials across gastrointestinal, lung, genitourinary, head and neck, and melanoma cancers were included. Female representation was reported in 1 of 10 abstracts (10%). None of the abstracts reported sex-stratified efficacy analyses, and none reported sex-stratified toxicity outcomes. The absence of sex-specific reporting was consistent across tumor types, therapeutic classes, and session formats, including plenary presentations. Conclusions: Among landmark phase III solid tumor trials presented at ASCO 2025, sex-specific reporting was largely absent at the abstract level, including in practice-changing studies. Limited visibility of sex-specific data at abstract presentation may constrain clinical interpretation and highlights an opportunity to improve reporting practices in oncology trials.