Introduction Colonic polyps containing a focus of invasive malignancy are increasing in frequency with the wider adoption of colonoscopic screening. Decision making as to the next course of action following endoscopic removal of a malignant polyp can be challenging. The ACPGBI position statement on malignant polyps outlines a scoring system to help predict the likelihood of lymph node metastasis and predicate surgical resection of the affected intestine and regional lymph nodes. The aim of this study was to analyse the benefit of this scoring system in predicting the presence of residual disease in patients with a malignant polyp.

Method Colorectal MDT decision making and outcomes of a consecutive series of malignant polyps treated between 2008 and 2014 was studied. Each polyp was assigned an ACPGBI score retrospectively to assess how well this predicted the presence of residual disease.

Results 70 patients (47 male) were identified as having a malignant polyp. Median follow-up was 27 months (range 0–58). Median age was 69 years (range 42–87). 36 (51%) polyps were detected during bowel cancer screening colonoscopy, 30 polyps were detected in symptomatic patients. 31 (45%) polyps were located in the rectum, 35 (51%) in the left colon and 3 (4%) in the right colon. 18 polyps were scored as low risk (ACPGBI score <2, chance of residual disease <5%). 15 patients were managed with endoscopic polypectomy only, all were recurrence-free during follow up. 3 patients underwent surgery, two after MDT recommendation and one as a result of perforation following polypectomy. None of these patients had residual disease in the specimen.

52 patients were deemed to have a moderate or high risk polyp (ACPGBI score 3 or more, >10% risk residual disease). 2 patients were deemed unfit for surgery and 2 patients declined surgery. 48 patients underwent surgery: residual (lymph node) disease was found in 3 patients (ACPGBI Scores 4,4 &5) and a further 1 patient (ACPGBI score 6), had a specimen clear of tumour but went on to develop metastatic disease giving an overall risk of residual disease of 8.3%. One patient is alive with metastatic disease and 3 patients have died post operatively, 1 (2.8%) of postoperative complications. The remaining patients are alive and recurrence-free.

Conclusion Low-risk malignant polyps are readily identified using a composite score and do not require surgical resection of the affected colon or rectum. Criteria used to identify moderate risk polyps are not specific enough as most patients undergoing surgery do not harbour residual disease. Piecemeal removal of polyps makes accurate risk assessment difficult. Accumulation of data such as this will allow fine-tuning of criteria used to identify patients at greatest risk of residual cancer after endoscopic resection of a malignant polyp.

Disclosure of interest None Declared.