In this longitudinal case series, five patients with Barrett oesophagus and high-grade dysplasia or intramucosal carcinoma had mutations that persisted post radiofrequency ablation (RFA)—in deep oesophageal glands or neighbouring squamous epithelium. De novo mutations were found in another three patients who had recurrence of pathology post RFA. The authors conclude, “Overall, recurrence of dysplasia post RFA reflects the multicentric origins of Barrett's clones and highlights the role of clonal selection in carcinogenesis”.