Cross-sectional analysis of 5,251 breast cancer clinical trials registered on ClinicalTrials.gov (2001–2025) to identify reasons, determinants, and temporal patterns of early termination (ET) before planned completion.
ET occurred heterogeneously: poor accrual was the top reason overall (39.2%), followed by sponsor/strategic decisions (22.4%) and operational/management issues (13.4%). Phase 2 trials had higher ET odds (OR=1.48, p<0.001), while multicenter design (OR=0.70) and non-treatment purpose (OR=0.61) were protective.
Retrospective cross-sectional design using registry data limits causal inference; reasons for ET are self-reported by sponsors and may be inconsistently recorded in ClinicalTrials.gov.
Phase 2 and single-center breast cancer trials are at highest risk of early termination due to poor accrual—trialists and funders should invest in recruitment planning and multicenter infrastructure upfront to protect trial completion.
