It is the first time researchers have studied the impact of pharma firm participation on the design and outcome of clinical trials of breast cancer treatments. As well as differences in results, the US team, from the University of North Carolina and the Dana Farber Cancer Institute also discovered significant differences in trial design in industry-sponsored research.
For over 15 years, the pharma industry has spent more annually on research than the entire budget of the National Institutes of Health - currently around $29bn (€22bn). For-profit pharma firms increasingly collaborate with academic medical centres and consequently, the potential for conflicts of interest have risen. Furthermore, several articles in respected journals have raised concerns over the integrity of these trials.
"Our study shines a flashlight on the issue of the rising role and potential impact of the pharmaceutical industry on breast cancer research and highlights important questions that need to be addressed through further research," said Dr Jeffrey Peppercorn, assistant professor of medicine at the University of North Carolina.
"It's been seen again and again in various branches of clinical medicine that studies that involve pharmaceutical industry sponsorship are more likely to have positive outcomes," he continued.
Dr Peppercorn and his team examined all clinical trials published in 10 journals in 1993, 1998 and 2003, a total of 140 trials. However, statistical analysis concentrated on the latest trials because, over the last decade, more stringent disclosure guidelines have made it easier to determine whether research was industry funded.
In 2003, 84 per cent of industry-supported studies showed positive results, compared with 54 per cent of non-industry trials. Trials sponsored by drug companies were also more like to target advanced, metastatic, disease.
However, Dr Peppercorn was quick to point out that the study didn't seek to suggest that the pharma industry does anything wrong. For example, the pattern could just be the result of pharma firms making better or safer choices about which drugs candidates to develop.
He said: "It's not fair to say at this point that it's necessarily related to biased interpretation of results. [Pharmaceutical firms] are excellent at developing new therapies, and there are many recent examples in breast cancer research."
Dr Peppercorn did, however, express concern that as industry funding becomes increasingly dominant, clinical research may become skewed towards certain areas at the expense of others. As an example, he said research on the optimal duration for therapy might become neglected because it is not directly related to drug development.
Also, studies into whether certain patients benefit from a given drug more than others could fall by the wayside, according to Dr Peppercorn.
The report, published in the journal Cancer, also found that industry research is more likely to use 'single arm' trial designs. In these studies, patients' response to therapy is measured only against their condition before the trial, not against a placebo or other therapy. In 2003, 66 per cent of industry studies were single-arm compared to only 33 per cent of other trials. However, Peppercorn said that this wasn't surprising because these studies are a key step in drug development.
The team found that over the last decade industry involvement - through co-authorship of the research paper, supply of drug or financial support - has increased from 44 to 58 per cent.
"If more and more research is funded by drug companies, then the limited amount of funding coming from other sources may need to be directed to address other questions," Peppercorn said.
Several of the world's largest pharma firms market breast cancer drugs. Genentech and Roche developed Herceptin (trastuzumab), which is approved alongside paclitaxel for use in breast cancer patients.
A spokesperson at Roche told DrugResearcher.com: "Whilst we cannot comment on behalf of all breast cancer trials, we can confirm that in the case of Herceptin, the results are consistent whether Roche has supported the trial or not."
They added: "All major known trials in the adjuvant setting for HER2 positive breast cancer have compared the addition of Herceptin to standard treatment (randomised) and shown that the treatment reduces the risk of breast cancer recurrence by half."
AstraZeneca has developed the aromatase inhibitor Arimidex (anastrazole), designed to treat post-menopausal women with hormone-responsive breast cancer. Novartis and Pfizer also market aromatase inhibitors - called Femara (letrozole) and Aromasin (exemestane) respectively. Novartis and Pfizer were unavailable for comment at the time of going to press.
A spokesperson for Eli Lilly, which markets breast cancer drug Gemzar (gemcitabine), said he was unable to comment, as he hadn't seen the report. However he did point out that Eli Lilly are "confident in the trials [it] performed."
The authors of the report acknowledge the "relatively small number of studies identified in each of the 3 years," and said that if more studies could have been taken into account, the results may have been different.
However, the authors said: "Given the importance of breast cancer as a public health problem and the current necessity of the pharmaceutical industry as a supporter of clinical breast cancer research, further study is needed…ultimately, to determine the potential impact on patient care."
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