The most frequent type of conflict was industry funding of the study, which was seen in 17 percent of papers. Twelve percent of papers had a study author who was an industry employee. Randomized trials with reported conflicts of interest were more likely to have positive findings.

"Given the frequency we observed for conflicts of interest and the fact that conflicts were associated with study outcomes, I would suggest that merely disclosing conflicts is probably not enough. It's becoming increasingly clear that we need to look more at how we can disentangle cancer research from industry ties," says study author Reshma Jagsi, M.D., D.Phil., assistant professor of radiation oncology at the U-M Medical School.

The researchers looked at 1,534 cancer research studies published in prominent journals. Results of this current study appear online in the journal Cancer.

"A serious concern is individuals with conflicts of interest will either consciously or unconsciously be biased in their analyses. As researchers, we have an obligation to treat the data objectively and in an unbiased fashion. There may be some relationships that compromise a researcher's ability to do that," Jagsi says.

For example, she says, researchers might design industry-funded studies in a way that's more likely to produce favorable results. They might also be more likely to publish positive outcomes than negative outcomes.

"In light of these findings, we as a society may wish to rethink how we want our research efforts to be funded and directed. It has been very hard to secure research funding, especially in recent years, so it's been only natural for researchers to turn to industry. If we wish to minimize the potential for bias, we need to increase other sources of support. Medical research is ultimately a common endeavor that benefits all of society, so it seems only appropriate that we should be funding it through general revenues rather than expecting the market to provide," Jagsi says.

Methodology: The researchers looked at all original clinical cancer research published in five top oncology journals and three top general medical journals in 2006. The journals included were the New England Journal of Medicine, the Journal of the American Medical Association, Lancet, the Journal of Clinical Oncology, the Journal of the National Cancer Institute, Lancet Oncology, Clinical Cancer Research and Cancer.

Articles were analyzed to determine declared funding sources and conflicts of interest. A conflict of interest was identified if it was explicitly declared by the authors, if an author was an employee of industry at the time of publication, or if the study had industry funding.

Note: If no author is given, the source is cited instead.

• Breast Cancer
• Cancer
• Leukemia
• Lung Cancer
• Colon Cancer
• Diseases and Conditions

• Double blind
• Heat shock protein
• Clinical trial
• Evidence-based medicine
• Hormone replacement therapy
• Embryonic stem cell