title: Response to Hersch et al.
authors.affiliation: Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK p.sasieni@qmul.ac.uk.
authors.forename: P D
authors.initials: PD
authors.lastname: Sasieni
authors.affiliation: Cancer Screening, American Cancer Society, Atlanta, GA, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Smith
authors.affiliation: Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK.
authors.forename: S W
authors.initials: SW
authors.lastname: Duffy