[1] UCL, Dept Behav Sci & Hlth, London WC1E 7HB, England
[2] UCL, Behav Sci & Hlth, Dept Behav Sci & Hlth, London, England
[3] UCL, Fac Med Sci, London, England
[4] Cheshire & Merseyside Canc Alliance, Chester, Cheshire, England
[5] Cheshire & Merseyside Canc Alliance, Liverpool, Merseyside, England
[6] Queen Mary Univ London, Wolfson Inst Populat Hlth, Ctr Prevent Detect & Diag, London, England
[7] Univ Surrey, Sch Hlth Sci, Canc Care, Guildford, Surrey, England