A new study suggests that clinical trials of breast cancer drugs are subject to 'spin' by researchers, with positive results exaggerated and serious side effects downplayed. The research, led by Professor Ian Tannock of the Princess Margaret Cancer Centre, Canada, analysed the results of 164 Phase III clinical trials of breast cancer treatments carried out between 1995 and 2011.

Although 92 of the trials had negative primary outcomes, around 60% of these instead focused on secondary end points. Prof. Tannock said, “basically negative studies are a little bit dressed up to look as though they may be positive” ( The Vancouver Sun , 10 Jan 2013). He suggested that this positive bias may be due to researchers hoping that their research will be more highly cited.

Around two-thirds of the studies did not state considerable side effect toxicity in the abstract, particularly when a treatment had improved overall survival or time to progression. Furthermore, about 20% did not include serious side effects in tables, with around one-third failing to mention them either in the abstract or in the discussion. This could lead to clinicians potentially overlooking serious associated toxicity.

The study also looked at whether positive results were more likely to be reported if the research was funded by the pharmaceutical company sponsoring the treatment; however, in this case they did not uncover any significant bias.

As this study suggests that patients might receive less effective treatment than expected and with more serious side effects, Prof. Tunnock said: “Better and more accurate reporting is urgently needed” ( The Telegraph , 10 Jan 2012). Richard Francis of Breakthrough Breast Cancer, UK, agrees, adding: “making clinical trial data freely available would decrease the potential for 'spin'” ( The Independent , 10 Jan 2013).