The occurrence and characteristics of endoscopically unexpected malignant degeneration in large rectal adenomas

Diagnostic assessment of large non-pedunculated rectal polyps revealed similar characteristics between unexpected cancers and adenomas. Unexpected cancers during EMR were non-lifting in 40%, endoscopically assessed as incomplete in 33%, and terminated prematurely in 60%. In treatment-naive patients, these factors should raise suspicion of malignancy and need discussion in a multidisciplinary team meeting for decision on further treatment strategies.