Factors affecting treatment decisions for endoscopically resected low- and high-risk malignant colorectal polyps in a screening setting.

Introduction: The European Guidelines for colorectal cancer screening of 2006 state that only high-risk endoscopically resected malignant colorectal polyps (MCPs), defined as poor/no differentiation or positive resection margins or lymphovascular invasion, require colonic resection.

Methods: A multicentre series of 954 patients with screen-detected MCP (northern Italy, 2005-2016, age 50-69) was studied to identify (1) the factors affecting the choice of colonic resection, and (2) the factors associated with deviation from the European Guidelines for low- and high-risk patients. Data analysis was based on multilevel logistic regression models.

Results: Five hundred sixty-four (59.1 %) patients underwent colonic resection. The factors significantly associated with surgical referral included: distal and rectal versus proximal tumour site (inverse association); sessile and flat versus pedunculated morphology (direct association); tumour size (direct); moderate/poor versus good differentiation (direct); adenocarcinoma of not otherwise specified type versus adenocarcinoma with a residual adenoma component (direct); positive versus negative resection margins (direct); lymphovascular invasion (direct); and high-grade versus low-grade/absent tumour budding (direct). In low-risk MCPs, tumour budding encouraged strongly the decision for surgery. In high-risk MCPs, a distal/rectal tumour site encouraged the follow-up option.

Conclusion: The identification of factors associated with treatment choices other than those currently recommended may help prioritise the clinical questions in the development of future guidelines.