Availability of results of interventional studies assessing colorectal cancer from 2013 to 2020.

Colorectal cancer (CRC) is one of the most frequent cancers worldwide. Our aim was to evaluate the availability of results of interventional studies studying CRC. We searched the ClinicalTrials.gov registry for all interventional studies on CRC management in adults completed or terminated between 01/01/2013 and 01/01/2020. To identify results, we searched for results posted on the ClinicalTrials.gov registry and/or published in a full-text article. Our primary outcome was the proportion of CRC interventional studies with available results (i.e. posted on the ClinicalTrials.gov registry and/or published in a full-text article). Secondary outcomes were 1) median time between primary completion and earliest date of results availability, 2) the cumulative percentage of interventional studies with results available over time 3) the cumulative percentage of interventional studies with results posted on the ClinicalTrials.gov registry over time and 4) the percentage of results available in open access. We identified 763 eligible interventional studies in ClinicalTrials.gov, which included 679 198 patients. Of these, 286 (37%) trials, including 270 845 (40%) patients, did not have any results available. Median time for results availability was 32.6 months (IQ 16.1-unreached). The cumulative percentage of interventional studies with available results was 17% at 12 months, 39% at 24 months and 55% at 36 months. Results were more likely available for trials that were randomized, completed, had one trial site in the United States, and with mixed funding. The cumulative percentage of interventional studies with results posted on ClinicalTrials.gov was 2% at 12 months. Results were available in open access for 420 (420/477 = 88%) trials. Our results highlight an important waste in research for interventional studies studying CRC.