Received: 2 July 2018
Accepted: 25 January 2019
First Online: 4 February 2019
Ethics approval and consent to participate
: Procedures were followed as outlined in accordance with ethical standards formulated in the Helsinki Declaration 1975 (and revised in 1983). Patients gave their written consent to usage of their tumor specimens, an approval was obtained from the University of Cologne Ethics Committee (reference number: 13–091).
: Not applicable.
: The authors declare that they have no competing interests.
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