Funding for this research was provided by:
Cancer Research UK (C16377/A17740)
Received: 9 January 2018
Accepted: 24 May 2018
First Online: 5 June 2018
Ethics approval and consent to participate
: The study materials and protocol were approved by NHS Health Research Authority: National Research Ethics Service (Reference: 14/NW/1104) and all participants gave written informed consent.
: The authors declare that they have no competing interests.
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