Large Traditional Serrated Adenomas (TSA ≥ 20mm) are an important subgroup of colorectal neoplasms. There is limited data about large TSAs and most information on these lesions has been derived from the analysis of smaller lesions. We sought to analyse the clinicopathological features of large TSAs in comparison to large Tubulovillous Adenomas (TVAs) in a multicenter prospective cohort.

We analysed the Australian Colonic Endoscopic Resection cohort, a multicenter, observational study of consecutively referred patients with large non-pedunculated colonic polyps (LNPCP). Participants were enrolled at 1 of 7 sites between July 2008 to February 2025. The clinicopathological data of large TSAs were compared with large TVAs.We analysed the Australian Colonic Endoscopic Resection cohort, a multicenter, observational study of consecutively referred patients with large non-pedunculated colonic polyps (LNPCP). Participants were enrolled at 1 of 7 sites between July 2008 to February 2025. The clinicopathological data of large TSAs were compared with large TVAs.

Among 4665 LNPCPs, there were 114 large TSAs (2.4%) and 2411 TVAs (51.6%). TSAs were more often left sided (70% vs 40%, p < 0.01) and occurred more frequently in women (61% vs 45%, p =0.004). Lesion size and morphology were comparable. SMIC rates were equivalent (10.2% vs 8.8%, p=0.77). Recurrence at first surveillance was similar (13.9% vs 10%, p = 0.29). Synchronous LNPCPs occurred in 11.4% vs 8.7% respectively (p=0.53). Post procedural bleeding (6.5% vs 9.1%, p=0.37) and significant deep mural injury (7.5% vs 4.5%, p=0.16) were comparable between the two groups.

We present novel data indicating that large TSAs are clinically significant lesions with an SMIC risk of 10.2%. They parallel TVAs in morphology and resection outcomes. Their management warrants the same meticulous approach applied to advanced adenomatous lesions, encompassing technical precision and vigilance during index and surveillance endoscopy for synchronous neoplasia.