What is claimed to be the first-ever study conducted to examine the impact of the drug industry on breast cancer research has concluded that clinical trials which are supported by drug manufacturers are more likely to report positive results than those that are not.
There are also “significant differences” in the design of trials and types of questions which industry-sponsored trials address compared to those without company sponsorship, according to the study, set to appear in the 1 April of the American Cancer Society journal Cancer.
The authors, led by Jeffrey Peppercorn of the School of Medicine at the University of North Carolina at Chapel Hill, acknowledge that the industry is a “significant contributor” to the R&D which is critical to developing new therapies, and that it spends far more than the US National Institutes of Health (NIH). However, the authors say that as collaborations between the for-profit drug industry and academic medical centres increase, concern has grown over the impact of for-profit sponsorship on the nature and quality of research and the potential for conflicts of interest. Studies in other areas of medicine have suggested that pharmaceutical sponsorship leads to a greater chance that a clinical trial will yield positive results, but the researchers say it was not yet clear how important this might be for patients and researchers, or whether this was also the case in cancer research.
With these issues in mind, the authors reviewed 140 studies reporting breast cancer therapy results published over the past decade in select journals at five-year intervals. They discovered that 67 (48%) of the studies reported some form of drug company involvement –through co-authorship, supply of drug or financial support – and that company participation increased from 44% in 1993 to 58% in 2003.
Most importantly, studies involving manufacturers were found to be more likely to report results favouring the experimental therapy, and significantly more likely to use “single-arm” designs – where all patients get the same treatment, with no control group to compare efficacy. Company-sponsored trials also tend to target patients with advanced disease, the researchers add.
The authors comment that while these types of studies are important for identifying new effective drugs, they may not answer questions about optimal dosing, duration and identification of patients who may have better or worse outcomes on treatment, and these are important clinical factors for treatment guidelines.
The impact of growing pharmaceutical industry involvement in breast cancer research appears to be similar to the case elsewhere in medical R&D, the researchers conclude. They warn that this relationship “may yield better therapies for treatment of breast cancer, but at the same time focus research on some clinical problems while neglecting others”.