1534 Background: While the official purpose of ClinicalTrials.gov is to satisfy regulatory requirements from the U.S. Food and Drug Administration meant to safeguard human subjects, the database also serves as the most comprehensive record of ongoing clinical trials for patient and provider use. Previous studies have focused on compliance with results reporting and completeness of information within restricted subsets of the database. Taking the perspective of a potential participant or their provider, the purpose of this study was to assess the accessibility of ClinicalTrials.gov contact information across actively recruiting oncology and non-oncology studies. Methods: This study included all actively recruiting interventional studies listed in the ClinicalTrials.gov database as of June 11, 2025. We assessed the completeness of location and contact information by multiple factors including oncology versus non-oncology study, sponsor type, trial phase, study start date, and date of last posted update. Within oncology studies, we further analyzed information availability by disease subsite. Results: We identified 47,703 actively recruiting interventional trials, among which 12,400 (26.0%) pertained to oncology. Within these oncology studies, 3178 (25.6%) had an industry sponsor, 9729 (78.5%) had a study phase listed (among which 59.4% were Phase 2 studies), and 4311 (34.8%) involved an FDA-regulated drug. Across both oncology and non-oncology studies, 2678 (5.6%) were missing any central contact information. While all trials had at least one study location listed, 3492 (7.3%) did not include a location-specific contact name and 9994 (21.0%) had neither a location-specific contact phone nor email address (24.1% for oncology, 19.8% for non-oncology). Within oncology trials, 50.9% of studies with an industry sponsor lacked any location-specific contact phone or email, compared to 11.3% for NIH sponsors and 14.9% for other (including academic) sponsors. Completeness of location-specific contact information was similar across trial phases. By oncology disease subsite, thoracic trials (29.8%) or those including multiple disease subsites (33.8%) most often lacked location-specific contact phone and email, whereas head and neck (15.4%) and neuro-oncology (16.3%) trials were least likely to do so. Conclusions: Location remains a primary means by which many potential trial participants filter clinical trial opportunities. Missing location-specific contact information, particularly among trials with industry sponsors, is an area of potential improvement that could be addressed by increased attention or more stringent registration requirements. While emerging strategies to improve clinical trial accessibility include artificial intelligence-powered platforms, these are only as good as the primary data on which they are built.
Sun et al. (Wed,) studied this question.