The researchers, from the Princess Margaret Cancer Centre and the University of Toronto in Toronto, looked at 164 randomized, controlled, phase 3 clinical trials of breast cancer treatments, the results of which were published between 1995 and 2011. They found 92 to be negative trials, in which the data did not demonstrate that the treatment under study had an effect on the primary end point, a specific event (such as survival or halting disease progression) that is measured at the end of a trial to see whether or not a given treatment works. But in 59% of the negative trials, the researchers used positive findings from secondary end points, which are additional events of interest but which the studies have not been designed specifically to address, to cast the treatment under study in a positive light.
The Canadian researchers also found bias in the way adverse effects of the treatment were discussed, with poor reporting of serious adverse effects (such as omitting mention of these problems in the abstract or conclusion) in about two-thirds of the publications with both positive and negative findings. They also found that publications of clinical trials with positive findings were twice as likely to underplay serious adverse effects compared with publications of negative studies.
Ian Tannock, MD, PhD, of Princess Margaret Cancer Centre, who guided the research, said better vigilance is needed to detect and eliminate bias and spin in clinical research. “Better and more accurate reporting is urgently needed,” Tannock said in a release. “Journal editors and reviewers, who give their expertise on the topic, are very important in ensuring this happen. However, readers also need to critically appraise reports in order to detect potential bias.”