Publication status of contemporary oncology randomised controlled trials worldwide

Little is known about the extent of selective publication in contemporary oncology randomised controlled trials (RCTs) worldwide. This study aimed to evaluate the rates of publication and timely publication (within 24 months) for contemporary oncology RCTs from all over the world. We also investigated the trial characteristics associated with publication and timely publication.

We identified all phase III oncology RCTs registered on ClinicalTrials.gov with a primary completion date between January 2008 and December 2012. We searched PubMed and EMBASE to identify publications. The final search date was 31 December 2015. Our primary outcome measure was the time to publication from the primary completion date to the date of primary publication in a peer-reviewed journal.

We identified 598 completed oncology RCTs; overall, 398 (66.6%) had been published. For published trials, the median time to publication was 25 months (interquartile range, 16-37 months). Only 192 trials (32.1%) were published within 24 months. Timely publication was independently associated with trials completed late in 2012. Trials conducted in Asia and other regions were less likely to have timely publication, but trials conducted in different locations were all equally likely to be published. Industry- and NIH-funded trials were equally likely to be published timely or at any time after trial completion. Among 391 published trials with clear primary outcomes, there was a trend for timely publication of positive trials compared with negative trials.

Despite the ethical obligations and societal expectations of disclosing findings promptly, oncology RCTs performed poorly.