Received: 18 September 2017
Accepted: 1 February 2019
First Online: 11 February 2019
Ethics approval and consent to participate
: Use of NRCT data reported here was approved by NRES Committee South Central - Oxford B (ref. 12/SC/0532). The NRCT was a member of the UK Association of Cancer Registries and was thereby permitted to process identifiable cancer registration data without patient consent according to exemption granted under the terms of Section 251 of the NHS Act 2006.
: Not applicable.
: The authors declare that they have no competing interests.
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