Funding for this research was provided by:
Cancer Research UK (C7923/A18348)
Received: 14 September 2017
Accepted: 20 April 2018
First Online: 2 May 2018
Ethics approval and consent to participate
: The Cancer Survival Group obtained ethical and statutory approvals from the National Research Ethics Service Committee London – Camden & Islington on 28 May 2013 (Research Ethics Committee reference 13/LO/0610, confirmed on 29 January 2015).
: The authors declare that they have no competing interests.
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