Overall survival with cetuximab every-2-weeks versus standard once-weekly administration schedule for first-line treatment of RAS wild-type metastatic colorectal cancer in patients with left- and right-sided primary tumour location.

Competing Interests: Conflict of interest statement The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: S. Kasper discloses honoraria (self) from Merck, Amgen, Roche, Sanofi, Aventis, Servier, BMS, MSD, Pierre Fabre and Lilly; honoraria (institution) from Merck, BMS, Amgen, Roche, and Lilly; advisory/consultancy roles with Merck, Amgen, Roche, Sanofi, Aventis, Servier, BMS, MSD, Novartis, Pierre Fabre and Lilly; research grants/funding (self) from Merck, Roche, BMS and Lilly; research grants/funding (institution) from Merck, Roche, BMS and Lilly; travel/accommodation expenses from Merck, Amgen, Roche, Sanofi, Aventis, Servier, and Lilly. C. Foch is a full-time employee of Merck Healthcare KGaA, Darmstadt, Germany. R. Esser was a full-time employee of Merck Healthcare KGaA, Darmstadt, Germany, during the work that is the subject of this letter and holds shares of Merck KGaA. F-X Lamy was a full-time employee of Merck Healthcare KGaA, Darmstadt, Germany during the work that is the subject of this letter. A. Zhang is a full-time employee of Merck Serono Co., Ltd., Beijing, China, an affiliate of Merck KGaA. T. Brodowicz discloses personal fees from Roche (lecture fee), Amgen (lecture fee, advisory board), Bayer (lecture fee, advisory board), Novartis (lecture fee, advisory board), PharmaMar (lecture fee, advisory board), Eisai (lecture fee, advisory board), and Lilly (lecture fee, advisory board), outside the submitted work. C. Zielinski discloses consultancy with Roche, Novartis, BMS, MSD, Imugene, ARIAD, Pfizer, Merrimack, Merck KGaA, FibroGen, AstraZeneca, Tesaro, Gilead, Servier, Shire, Lilly, and Athenex, and speaker's honoraria from Roche, Novartis, BMS, MSD, Imugene, ARIAD, Pfizer, Merrimack, Merck KGaA, FibroGen, AstraZeneca, Tesaro, Gilead, Servier, Shire, Lilly, and Athenex. All remaining authors have nothing to disclose.