ABSTRACT Aim: CPGs and consensus statements (CSs) are used to apply evidence-based medicine or expert recommendations to routine clinical practice. Here we explore the prevalence and transparency of self-reporting of financial FCOIs and their relationship with endorsement of specific drugs. Methods: An electronic search of MEDLINE was conducted to identify CPGs and CSs in breast, colorectal, lung and prostate cancer published between January 2003 and October 2013. The search was restricted to English language articles evaluating systemic therapy. When more than one CPG or CS from the same source was identified, the most recent version was evaluated. Particular attention was paid to collecting data on self-reporting of funding sources, author FCOIs and involvement of manuscript writers who were not listed as authors. The association between endorsement of a specific drug in the abstract of the guideline and author FCOIs with the company marketing that drug was evaluated. Results: In total, 142 articles were evaluated; 64% were CPGs and 36% were CSs. 41% of articles addressed breast cancer, 20% colorectal cancer, 25% lung cancer, 11% prostate cancer and 3% more than one tumor type. Only 45% of articles explicitly reported funding sources and of these, 65% disclosed partial or full industry sponsorship. Use of medical writers was declared in 13%, but among the other articles, only 17% of articles explicitly reported that authors were involved in the writing and final approval of the manuscript. Author FCOIs were declared in 45% of articles, 23% affirmed no FCOIs and 31% did not include disclosures of FCOIs. The proportion of articles reporting FCOIs increased from 11% in 2003 to 93% in 2013. There was a significant association between FCOIs of any author and endorsement of specific drugs (OR 7.29, 95% CI 2.17-24.49, P = 0.001). Similar results were obtained when analysis was limited to first, senior or corresponding author (OR 3.81, 95% CI 1.34-10.79, P = 0.01). Conclusions: Reporting of FCOIs in CPGs and CSs has improved in the last decade. However, published expert recommendations may still be influenced by use of medical writers or FCOIs of authors. Author FCOIs are associated with endorsement of specific drugs. Disclosure: B. Seruga: Advisory role for Sanofi-Aventis, Astellas Honorarium: Sanofi-Aventis, Janssen, GSK. All other authors have declared no conflicts of interest.