Objectives: Nonpublication of results of clinical trials can contribute to inappropriate medical decisions. The primary aim of this systematic review was to investigate publication delays between conference abstracts and full journal publications from randomized controlled trial results of new anticancer agents for breast cancer. The review was restricted to anticancer agents previously, or due to be, appraised in the United Kingdom by the National Institute for Health and Clinical Excellence. A secondary objective was to identify whether there are any apparent biases in the publication and reporting of these trials.

Methods: We searched six electronic databases up to August 2007, including Medline and the Cochrane Library. Two reviewers independently selected studies, extracted and assessed the data.

Results: Six anticancer treatments were identified: docetaxel, paclitaxel, trastuzumab, gemcitabine, lapatinib, and bevacizumab. Of eighteen included trials, only four publications from three trials reported the same outcomes in both abstract and full publication. Time delays ranged from 5 to 19 months. Eleven trial abstracts were still without a full publication at the end of our searches, varying from 3 to 38 months since abstract publication. Observational analysis revealed no particular publishing biases.

Conclusions: Whereas delays in publication appear reasonable over a period of months, many were not published in full over a period of years and others would appear to be unlikely to ever be published. Further research should investigate the impact of publication delays on the availability of new drug treatments in clinical practice.