SFRP4 and polyp: The variables selected as the most informative were CGI methylation of HPP1, APC, SFRP4, p16, ESR1 and WIF1. Re-analysing the data with this model and grouping the neoplasia-free and polyp patients together as non-cancer subjects led to the correct classification of 29 out of 33 (87.9%, P=2.94 × 10−10) individuals.