(A) Number of KRAS mutations detected by mutation concentration by each technology with 100 copies mutant allele frequency. (A) Number of KRAS mutations detected by mutation concentration by each technology with 100 copies mutant allele frequency. (B) Number of mutations detected by mutation concentration by each technology with 50 copies mutant allele frequency. ddPCR, droplet digital PCR; MALDI-TOF, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. James L Sherwood et al. ESMO Open 2017;2:e000235 Copyright © European Society for Medical Oncology. All rights reserved.