Trial sponsorship and self-reported conflicts of interest in breast cancer radiation therapy: An analysis of prospective clinical trials.

PURPOSE: We aim to assess any association between study and self-reported conflict of interest (COI) or trial sponsorship in breast cancer radiation clinical trials.

MATERIALS AND METHODS: We searched PubMed for all clinical trials (CTs) published between 09/2004 and 09/2014 related to breast cancer. We included only radiotherapy CTs with primary clinical endpoints. We classified eligible trials according to the funding source, presence or absence of conflict of interest, study conclusion and impact factor (IF).

RESULTS: 1,603 CTs were retrieved. 72 randomized clinical trials were included for analysis. For-profit (PO), not for profit organization (nPO), none and not reported sponsorship rates were 9/72 (12.5%), 35/72 (48.6%), 1/72 (1.4%), 27/72 (37.5%), respectively. Present, absent or not reported COI were found in 6/72 (8.3%), 43/72 (59.7%) and 23/72 (32%) of the CTs, respectively. Conclusion was positive, neutral and negative in 57/72 (79.1%), 9/72 (12.5%) and 6/72 (8.4%) of the trials, respectively. Positive conclusion was reported in 33/44 (75%) funded trials (PO and nPO) and 5/6 (83.3%) CTs with reported COI. On univariate analysis no association with funding source (P=0.178), COI (P=0.678) or trial region (P=0.567) and trial positive conclusion was found. Sponsored trials (HR 4.50, 95CI-0.1.23-16.53;P=0.0023) and positive trials (HR 4.78, 95CI- 1.16-19.63;P=0.030) were more likely to be published in higher impact factor journals in the multivariate analysis.

CONCLUSIONS: nPO funding was reported in almost 50% of the evaluated CTs. No significant association between study conclusion and funding source, COI or trial region was identified. Sponsored trials and positive trials were more likely to be published in higher impact factor journals.