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.