eP335 - Cancer Risk in Colorectal Polyps with High Grade Dysplasia and Intramucosal Carcinoma

Purpose/Background: Detection of polyps during screening colonoscopy is common and encountered in up to 40% of patients. Histologic findings such as high-grade dysplasia (HGD) and intramucosal carcinoma (IMCa) are rare but may be found in 1-5% of polyps. While these findings are not diagnostic of cancer, presence of HGD is associated with increased risk of cancer, and endoscopic biopsies are often unable to provide architectural detail to determine the presence of cancer. The purpose of this study was to evaluate malignancy risk in polyps with HGD or IMCa treated with oncologic resection and/or less invasive methods, and to identify factors associated with increased cancer risk within this population.Methods/Interventions: Retrospective review was performed to identify patients with polyps containing biopsy proven HGD or IMCa from 2017-2023 at a single tertiary hospital. Relevant patient, procedure, perioperative, and pathologic data was reviewed. Only patients with biopsy proven HGD or IMCa, followed by endoscopic or surgical resection were included.Results/Outcomes: 20 patients were identified for review. 12 (60%) patients were female, average age was 69 years, and average polyp size was 31mm. 16 patients were found to have HGD, 2 with IMCa, and 2 with both HGD and IMCa. 8 patients had HGD or IMCa within tubular adenomas, 9 within tubulovillous adenomas, and 3 within villous adenomas.Of these, initial operative approach included 8 patients that underwent planned segmental colectomy and 12 that attempted less invasive non-oncologic excision, 10 of which were performed successfully. 5 patients underwent initial endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD), 2 of which were converted to segmental resection intraoperatively, and 1 that underwent abdominoperineal resection (APR) at a later date. 4 patients underwent combined endo-laparoscopic polypectomy (CELS), 1 of which was converted to an open full thickness wedge resection. The remaining 3 patients underwent transanal excision. Ultimately, cancer was identified in 8 (40%) patients. Of these, 2 patients had T1 lesions, 5 had T2 lesions and 1 did not have adequate T or N staging at time of review. Additionally, 1 patient underwent full thickness wedge resection and did not undergo lymphadenectomy. Of the 6 patients with an oncologic resection, 5 underwent laparoscopic segmental colectomy and 1 APR. All 6 patients with lymphadenectomy had N0 disease on pathologic review. Notably, of the 10 patients that underwent successful non-oncologic polyp excision, 8 (80%) had benign pathology on final review. When comparing patients with cancer versus those without, the average age was higher in patients whose polyps harbored cancer (77 vs. 63 years, p=.010). Specifically, age greater than 70 was associated with a higher cancer risk (p=0.037). Other patient and polyp factors such as histology, morphology, location, and size were not associated with an increased risk of cancer.Conclusion/

Discussion: Polyps with HGD or IMCa had a 40% rate of cancer on complete pathologic evaluation. Additionally, age greater than 70 years was associated with a higher risk of cancer in this population. Therefore, a high index of suspicion for cancer should be maintained in elderly patients with HGD or IMCa. However, in appropriately selected patients, benign pathology was found in 80% of cases managed with less invasive procedures such as EMR/ESD, CELS, and transanal excision. Therefore, less invasive approaches should be considered in cases with suspected benign lesions amenable to these approaches.Patient, Polyp, and Procedural DataPatient demographics, polyp characteristics, and procedural choices for patients with benign vs. malignant pathology.