The sample size calculation was determined for a non-inferiority study. Assuming an ADR of 28% with conventional chromoendoscopy in patients with Lynch syndrome, a 15% non-inferiority margin, a one-sided significance level of 0.05 powered at 80% and a 10% of drop-off. Based on these assumptions, it was determined that 122 patients were required for each arm (a total of 244).