Research waste in randomized controlled trials of endometrial cancer: a 20-year cross-sectional study

Background Randomized controlled trials (RCTs) provide high-level evidence for the management of endometrial cancer. However, research waste—including non-publication, inadequate reporting, and avoidable design flaws—remains a major challenge in clinical research. To our knowledge, no previous study has systematically evaluated research waste in RCTs of endometrial cancer. This study aimed to assess the characteristics of RCTs and quantify the extent of research waste over the past 20 years. Methods We conducted a cross-sectional analysis of RCTs registered on ClinicalTrials.gov between January 2004 and January 2024. Publication status was identified through PubMed and Scopus. Reporting quality was evaluated using the CONSORT checklist, and methodological quality was assessed using the Cochrane risk-of-bias tool. Research waste was defined as the presence of at least one of the following: non-publication, inadequate reporting, or avoidable design limitations. Logistic regression analyses were performed to identify factors associated with research waste. Results A total of 144 RCTs were included, of which 57 (39.6%) were published. Overall, 129 trials (89.6%) exhibited at least one feature of research waste. Among published trials, 52.6% had adequate reporting, and 43.9% showed avoidable design flaws. Trials with double- or multi-blind designs were more likely to be adequately reported and had a lower risk of research waste. Multicenter trials and those conducted in North America were more likely to be cited in clinical guidelines. Prospective data reuse was rare (1.8%). In multivariate analysis, blinding design was independently associated with reduced research waste. Conclusions Research waste is highly prevalent in RCTs of endometrial cancer. Improving trial design, promoting multicenter collaboration, and strengthening reporting standards may help reduce research waste and enhance the translation of evidence into clinical practice.