What happens when a clinical trial is over?


After a clinical trial is completed, researchers look carefully at the data collected during the trial to understand the meaning of the findings and to plan further research. After a phase I or phase II trial, the researchers decide whether or not to move on to the next phase or stop testing the intervention because it was not safe or effective. When a phase III trial is completed, the researchers analyze the data to determine whether the results have medical importance and, if so, whether the tested intervention could become the new standard of care.

The results of clinical trials are often published in peer-reviewed scientific journals. Peer review is a process by which cancer research experts not associated with a trial review the study report before it is published to make sure that the data are sound, the data analysis was performed correctly, and the conclusions are appropriate. If the results are particularly important, they may be reported by the media and discussed at a scientific meeting and by patient advocacy groups before they are published in a journal. Once a new intervention has proven safe and effective in a clinical trial, it may become a new standard of care.

The FDA Amendments Act of 2007 requires that researchers report the "basic" results of clinical trials that tested FDA-regulated and FDA-approved chemical or biologic agents or medical devices in ClinicalTrials.gov, a publicly accessible database maintained by the U.S. National Library of Medicine (NLM). Basic trial results must be submitted whether or not the results are published in a peer-reviewed scientific journal and include the following items:

  • Demographic and baseline information about the participants
  • The progress of the participants through each stage of the trial (e.g., the number of participants who left the trial and at which stage)
  • Results for the primary and secondary outcomes (also called endpoints) measured in the trial (e.g., tumor response, disease-free survival, overall survival, quality of life, etc.)
  • A point of contact for the trial (to obtain additional information about the trial and its results)

More information is available on the About the ClinicalTrials.gov Results Database page. NLM's website also has an FAQ that lists other ways to find clinical trial results.

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