A substantial number of published clinical cancer studies are compromised by potential conflicts of interest that may encourage researchers to report outcomes favourable to industry, a new study has found.

A team led by Dr Reshma Jagsi of the University of Michigan in the US reviewed cancer studies that appeared in eight respected journals, including the New England Journal of Medicine, the Journal of the American Medical Association, the Lancet and the Journal of Clinical Oncology, during 2006. The team’s findings were published in the 15 June issue of CANCER, a peer-reviewed journal of the American Cancer Society.

Of the 1,534 cancer studies identified in the aforementioned journals, 29% had potential conflicts of interest that were apparent from published author declarations and authorship lists (including industry funding, consulting fees paid to authors, and co-authorship by company employees), while 17% declared industry funding, Jagsi et al reported.

Potential conflicts of interest were most often found in articles with primary authors from departments of medical oncology (45%), from North America (33%) and with male first and senior authors (37%), they noted.

Randomised clinical trials that assessed patient survival were more likely to report a survival advantage associated with the intervention used when a potential conflict of interest was present, the study revealed.

It also showed that studies with industry funding were more likely to focus on treatment than those without industry backing (62% versus 36%). Studies with industry funding were less likely to focus on epidemiology, prevention, risk factors, screening or diagnostic techniques (20% versus 47%).

The ties between clinical researchers and companies that make drugs and medical devices have become increasingly complex and controversial, particularly as researchers in the US compete for scarce federal funding, the authors pointed out.

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,” they commented.