Funding for this research was provided by:
Wellcome Trust (101103/Z/13/Z, 106698/B/14/Z)
Division of Cancer Epidemiology and Genetics, National Cancer Institute (HHSN261200800001E)
Received: 24 November 2017
Accepted: 5 February 2018
First Online: 14 February 2018
Ethics approval and consent to participate
: The study protocol (NCT02157259) and related documents were approved by regional and national Ethics Committees. Consent was provided by participants or representatives of participants as appropriate before participating.
: Not applicable.
: The authors declare that they have no competing interests.
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