A simplified algorithm to evaluate the risk of submucosal invasive cancer in large (>/=20mm) non-pedunculated colonic polyps.

BACKGROUND AND AIMS: Recognition of submucosal invasive cancer (SMIC) in large (20mm) non-pedunculated colonic polyps (LNPCPs) informs selection of the optimal resection strategy. LNPCP location, morphology and size influence the risk of SMIC, however currently no meaningful application of this information has simplified the process to make it accessible and broadly applicable. We developed a decision-making algorithm to simplify the identification of LNPCP subtypes with increased risk of potential SMIC. METHODS: Patients referred for LNPCP resection from September 2008-November 2022 were enrolled. LNPCPs with SMIC were identified from endoscopic resection specimens, lesion biopsies, or surgical outcomes. Decision tree analysis of lesion characteristics identified in multivariable analysis was used to create a hierarchical classification of SMIC prevalence. RESULTS: 2451 LNPCPs were analysed. 1289 (52.6%) were flat, 1043 (42.6%) nodular and 118 (4.8%) depressed. SMIC was confirmed in 273 (11.1%) of LNPCPs and associated with depressed and nodular versus flat morphology (OR 35.7 CI 22.6-56.5 and 3.5 CI 2.6-4.9, p<0.001 respectively); left versus right colon location (OR 3.2, CI 2.5-4.1, p<0.001); non-granular (NG) versus granular (G) (OR 2.4 CI 1.9-3.1, p<0.001) and size (OR 1.12 per 10mm increase CI 1.05-1.19, p<0.001). Decision tree analysis targeting SMIC identified 8 terminal nodes: SMIC prevalence was 62% in depressed LNPCPs, 19% in nodular left colon LNPCPs and 20% in nodular right colon NG LNPCPs. CONCLUSIONS: This decision-making algorithm simplifies identification of LNPCPs with an increased risk of potential SMIC. When combined with surface optical evaluation, it facilitates accurate lesion characterisation and resection choices.

Geometry of cold snare polypectomy and risk of incomplete resection.

BACKGROUND: Cold snare polypectomy (CSP) is safer than and equally efficacious as hot snare polypectomy (HSP) for the removal of small (<10mm) colorectal polyps. The maximum polyp size that can be effectively managed by piecemeal CSP (p-CSP) without an excessive burden of recurrence is unknown. METHODS: Resection error risks (RERs), defined as the estimated likelihood of incomplete removal of adenomatous tissue for a single snare resection pass, for CSP and HSP were calculated, based on an incomplete resection rate. Polyp area, snare size, estimated number of resections, and optimal resection defect area were modeled. Overall risk of incomplete resection (RIR) was defined as RIR=1 - (1 - p)n, where p is the RER and n the number of resections. RESULTS: A 40-mm polyp has a four times greater area than a 20-mm polyp (314.16mm2 vs. 1256.64mm2), and requires three times more resections (11 vs. 33, respectively, assuming 8-mm piecemeal resection pieces for p-CSP). RIRs for a 40-mm polyp by HSP and p-CSP were 15.1%-23% and 40.74%-60.60% respectively. CONCLUSION: RER is more important with p-CSP than with HSP. The number of resections, n, and consequently RIR increases with increasing polyp size. Given the overwhelming safety of CSP, specific techniques to minimize the RER should be studied and developed.

Endoscopic resection of large anastomotic polyps is safe and effective.

BACKGROUND: Large (≥20mm) adenomatous anastomotic polyps (LAAPs) are uncommon. Data pertaining to their prevalence, characteristics, and the efficacy of endoscopic resection (ER) are absent. A safe and effective strategy for ER would reduce morbidity and healthcare costs. METHODS: Large nonpedunculated colorectal polyps of ≥20mm (LNPCPs) referred for ER were prospectively studied. Multiple data points were recorded including anastomotic location, polyp morphology, resection modality, complications, and technical success. RESULTS: Over 7 years until November 2022, 2629 lesions were referred. Of these, 10 (0.4%) were LAAPs (median size 35 mm [interquartile range (IQR) 30-40mm]). All LAAPs were removed by piecemeal endoscopic mucosal resection (EMR), most (n=9; 90%) in combination with cold-forceps avulsion with adjuvant snare-tip soft coagulation (CAST). On comparison of the LAAP group with the conventional LNPCP group, CAST was more commonly used (90% vs. 9%; P<0.001) and deep mural injury (DMI) type II was more frequent (40% vs. 11%, P=0.003); however, significant DMI (III-V) did not occur. At 6 month (IQR 5.25-6 months) surveillance, there was no recurrence in any of the 10 cases. There were no serious adverse events. CONCLUSIONS: LAAPs present unique challenges owing to their location overlying an anastomosis. Despite these challenges they can be safely and effectively managed endoscopically without recurrence at endoscopic follow-up.