Competing interests
RCF is named on patents related to the Cytosponge and related assays that have been licenced to Medtronic by the Medical Research Council. RCF is a shareholder in Cyted Ltd, a company working on early detection technology. PDS reports consulting fees paid to his organisation from GRAIL Inc, outside of the submitted work and being on the advisory committee for NHS England on the use of the Cytosponge (unpaid). The remaining authors have no conflicts of interest to declare.