Public availability of results of trials assessing cancer drugs in the United States.

Purpose: To evaluate to what extent results of completed trials of cancer drugs conducted in the United States are publicly available at ClinicalTrials.gov, as required by the Food and Drug Administration Amendments Act (FDAAA), or are published in journals.

Methods: We searched ClinicalTrials.gov for cancer trials governed by the FDAAA: phase II to IV trials assessing drugs in the United States with a primary completion date between December 26, 2007, and May 31, 2010. For each trial, we also searched PubMed to identify the publication of results. We assessed the cumulative percentages of posted or published results over time by using the Kaplan-Meier method.

Results: We identified 646 trials, including 209 randomized controlled trials (RCTs). At 12 months after completion of the trials, the cumulative percentages of trials with results posted at ClinicalTrials.gov, published in journals, and available either at ClinicalTrials.gov or in journals were 9% (95% CI, 7% to 11%), 12% (95% CI, 10% to 15%), and 20% (95% CI, 17% to 23%), respectively, and for RCTs, the percentages were 12% (95% CI, 8% to 16%), 5% (95% CI, 2% to 8%), and 17% (95% CI, 12% to 22%), respectively. At 36 months, these percentages were 31% (95% CI, 28% to 35%), 35% (95% CI, 31% to 39%), and 55% (95% CI, 51% to 59%), respectively, and for RCTs, they were 38% (95% CI, 31% to 45%), 32% (95% CI, 25% to 39%), and 56% (95% CI, 48% to 62%), respectively. Public availability of phase III trials was 15% (95% CI, 7% to 23%) at 12 months, 39% (95% CI, 27% to 49%) at 24 months, and 64% (95% CI, 50% to 73%) at 36 months.

Conclusion: Despite the FDAAA, results for nearly half the trials of cancer drugs in the United States were not publicly available 3 years after completion of the trials.