Figure 1: Mutational signatures found in EAC.

(a) Five mutational signatures were detected in EAC. Each signature is represented by the proportion of somatic substitutions (C>A, C>G, C>T, T>A, T>C and T>G). Substitutions are displayed in a trinucleotide context (including information about the bases immediately 3′ and 5′ to the mutated base) resulting in 96 potential contexts. (b) Contribution of mutational signatures operative in individual tumours. Each bar represents a tumour and the y axis represents the contribution of each signature within tumours, shown as number of mutations per Mb. The BRCA, the unknown and APOBEC signatures were most prevalent only in one tumour each (BRCA contributed ~57% of OESO_1636 mutations and unknown signature represents 67% of OESO_0303 mutations). The APOBEC signature, previously described in EAC and other tumour types¹¹, contributes to more than 50% of the mutations in tumour OESO_1154, with small contributions in other samples. The age signature, previously described in EAC, is the second major operative mutational processes in this cohort. The signature characterized by T>G at TT sites is the most prominent within this cohort, representing ≥40% of mutations in 10 of 22 tumours (Supplementary Fig. 1).