An important longer-term complication of EMR of large flat colonic neoplasia is the phenomenon of residual polyp tissue or polyp recurrence, which will be the focus of the proposed research study. Recurrence is detected by surveillance colonoscopies (SC), which are performed at defined intervals after the index procedure. Our current standard for safe surveillance interval at Westmead after >= 20mm EMR is 5 months (SC1). In the largest study to date, the Australian Colonic EMR (ACE) study, recurrence at SC1 stands at 16.5% for all patients.