Frequency, Nature, Effects, and Correlates of Conflicts of Interest in Published Clinical Cancer Research

BACKGROUND: Relationships between clinical researchers and industry are becoming increasingly complex. The frequency and impact of conflicts of interest in the full range of high-impact, published clinical cancer research is unknown. METHODS: The authors reviewed cancer research published in 8 journals in 2006 to determine frequency of self-reported conflicts of interest, source of study funding, and other characteristics. They assessed associations between the likelihood of conflicts of interest and other characteristics by using chi-squared testing. They also compared the likelihood of positive outcome in randomized trials with and without conflicts of interest by chi-squared testing. RESULTS: The authors identified 1534 original oncology studies; 29% had conflicts of interest (including industrial funding) and 17% declared industrial funding. Conflicts of interest varied by discipline (P<.001), continental origin (P<.001), and sex (P<.001) of the corresponding author and were most likely in articles with corresponding authors from departments of medical oncology (45%), those from North America (33%), and those with male first and senior authors (37%). Frequency of conflicts also varied considerably depending upon disease site studied. Studies with industrial funding were more likely to focus on treatment (62% vs 36%; P<.001), and randomized trials that assessed survival were more likely to report positive survival outcomes when a conflict of interest was present (P=.04). CONCLUSIONS: Conflicts of interest characterize a substantial minority of clinical cancer research published in high-impact journals. Therefore, attempts to disentangle the cancer research effort from industry merit further attention, and journals should embrace both rigorous standards of disclosure and heightened scrutiny when conflicts exist. Cancer 2009;115:2783-91. (C) 2009 American Cancer Society.