Specification and characteristics of patient-reported outcome measures in adult oncology trials: A ClinicalTrials.gov registry-based cross-sectional study

Background Patient-reported outcome measures (PROMs) provide important insights into health-related quality of life (HRQoL), symptom burden, functional status, and treatment impact from the patient perspective. As patient-centered outcomes gain increasing importance in oncology research, regulatory evaluation, and health technology assessment (HTA), understanding how PROMs are incorporated into oncology clinical trials has become increasingly relevant. However, current evidence on the specification and positioning of PROMs in registered oncology trials remains limited. Methods We conducted a retrospective, registry-based cross-sectional study of oncology interventional trials registered on ClinicalTrials.gov between January 2014 and December 2025. Eligible studies enrolled adults with a cancer diagnosis, used an interventional design (Phase I–IV), and explicitly specified at least one PROM as a primary, co-primary, or secondary outcome. Trials with co-primary PROMs were classified as having a primary PROM component. Descriptive statistics were used to summarize trial and PROM characteristics. Results A total of 528 eligible oncology interventional trials met the inclusion criteria. PROMs were specified mainly as secondary outcomes with 11 trials (2.1%) listing a PROM as a primary endpoint. Most studies used one PROM instrument (72.6%), and the majority relied on cancer-specific measures (85.8%). The EORTC QLQ-C30 was the most frequently used instrument (64.8%). Academic or research institutions accounted for 69.5% of included trials. Conclusion In this registry-based cohort of PROM-positive oncology interventional trials, PROMs were most often specified as secondary endpoints and were typically assessed using cancer-specific instruments. Their positioning suggests a complementary role alongside traditional efficacy and safety outcomes and highlights the importance of clear registry-level specification of PROM objectives, measures, and endpoint roles.