Introduction Previous studies on large sessile colorectal polyps (LSCPs) suggest that management (Endoscopic vs Surgical) and outcomes (complication rates, incomplete resection, recurrence rates) may vary. The advent of the Bowel Cancer Screening Program (BSCP) provides opportunities to study this lesion subgroup systematically. We report the experience and outcomes of managing LSCPs in a single Welsh screening centre undertaking screening colonoscopy within an established local multidisciplinary discussion forum (colorectal surgery, endoscopy, radiology & histopathology).

Methods Outcome data was collected prospectively for BSCP participants with a benign adenoma greater than 20mm between October 2009 and December 2011 in Cardiff and the Vale of Glamorgan. Each patient was discussed at a multidisciplinary team meeting. Standard protocol for piecemeal EMR or histology suggesting uncertain margins was to cheque the site at 3 months and 12 months post index therapeutic procedure.

Results LCSP accounted for 3.42% of adenomas, mean size 32.2mm (1.02% were LSCP > 40mm). 33/40 (82.5%) LCSP were managed endoscopically, with either enbloc EMR, piecemeal EMR, or laparoscopically-assisted EMR. Of these, 84.8% had successful endoscopic resection with no recurrence at 3 to 12 months. Recurrent or residual polyp was detected in 1/28 (3.6%) at 3 months, with no recurrence at 12 months. 4/29 (13.8%) of lesions initially managed endoscopically subsequently required surgery. 3/4 (75%) went on to undergo TEM and 1/4 (25%) a segmental colonic resection. Indications included technical limitations to endoscopic management; difficult access or previous attempts at endoscopic resection at a different centre. No significant adverse events occured in the endoscopically managed group. There was a cancer rate (in lesions initially managed endoscopically) of 5.7% - no residual cancer was detected following definitive treatment.

Surgery was the initial therapeutic modality in 7/40 (17.5%); 5/7 (71.4%) had segmental colectomy and 2/7 (28.6%) had TEM. No cancer was found in any surgically resected specimen.

Conclusion Most patients with LSCPs can be managed endoscopically with good outcomes, including a low adverse event profile and recurrence rate. A small proportion of cases may turn out to have carcinoma that was not possible to diagnose in pre-procedure biopsies and thus require further surgery. Our study supports high quality endoscopic assessment and multidisciplinary team discussion as important factors in achieving optimal patient management and has resulted in piloting a change of practise across the BCSP to minimise variation in outcomes.

Disclosure of Interest None Declared.