Industry-sponsored studies of breast cancer therapies are more likely to report positive results than those funded in other ways, researchers from the University of North Carolina at Chapel Hill and the Dana Farber Cancer Institute report in a paper published by Cancer online. But this may not result from a biased interpretation of the results.

“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,” commented lead author Jeffrey Peppercorn, assistant professor of medicine in UNC School of Medicine’s division of hematology and oncology. For example, the authors cite previous analyses suggesting that studies sponsored by pharma are around four times (odds ratio 3.6) more likely to report positive outcomes or pro-industry conclusions than those funded by other groups. In multiple myeloma, 74% of randomised controlled studies sponsored by pharma favoured the experimental over control drug. This compared with 47% of those funded in other ways. However, the new paper is the first to examine the relationship between funding source and outcomes in breast cancer.

The researchers reviewed breast cancer clinical trials published in 10 English-language medical journals in 1993, 1998 and 2003. Their statistical analysis focused on papers published in 2003 because more stringent disclosure guidelines made it easier to identify the funding source. In 2003, 57% of studies reported pharmaceutical involvement. Eighty-four per cent of industry-supported studies showed positive results, compared with 54% of non-industry studies. However, Peppercorn noted: “It’s not fair to say at this point that it’s necessarily related to biased interpretation of results.”

Study design differences related to funding

The analysis revealed several differences in study design depending on the funding source. For example, 66% of trials with industry involvement used a single-arm study design, without a comparison group, compared to 33% of non-industry studies. Peppercorn comments that as these studies are a key step in drug development, this difference isn’t surprising. Furthermore, 72% of trials with industry involvement enrolled people with metastatic disease compared to 46% of non-industry studies. Again this may reflect the fact that new treatments tend to be used in patients with advanced cancer for safety and ethical reasons. Half of the pharma-sponsored studies assessed experimental hormonal or biologic therapy compared to a third of those with other funding sources, although this difference did not reach statistical significance.

“The significance of our study is not to say that the drug industry does anything wrong – they are excellent at developing new therapies, and there are many recent examples in breast cancer research,” Peppercorn says. “But 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.”

In particular, industry’s increasingly dominance as a source of research funding may lead to the neglect of clinical questions that aren’t directly related to drug development, Peppercorn warned. For example, the optimal timing, sequencing and duration of many proven treatments are unclear. Furthermore, studies need to identify subgroups of patients likely to benefit or develop adverse events with current drugs and to assess long-term outcomes with current therapies. “Pursuing these questions may not always be in the financial interests of companies that are selling approved therapies,” the paper comments. They concluded by calling for further research, including an analysis of unpublished studies facilitated by the trial registry, to evaluate the impact of pharma involvement in clinical research.

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