Received: 7 July 2018
Accepted: 25 January 2019
First Online: 4 February 2019
Ethics approval and consent to participate
: All patients gave written informed consent for use of their tumor tissue for research purposes. The study was approved by the institutional ethics committee from the University Hospital Essen (16–6915-BO) and fully conforms to the principles outlined in the declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.
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