APC and colorectal cancer: Moreover, the proportion of patients with positive ctDNA at baseline was low, and the frequencies of mutated genes in plasma ctDNA samples from patients with LARC in our study were inconsistent with those measured from DNA tissue samples recorded in The Cancer Genome Atlas database.36,37 For example, the frequency of APC mutations in colorectal cancer tissue samples is reported to be ~80%,36,38 whereas we found a mutation frequency of only 17.1%.