LONG-TERM OUTCOMES AFTER ENDOSCOPIC REMOVAL OF MALIGNANT COLORECTAL POLYPS – RESULTS FROM A RETROSPECTIVE COHORT STUDY

Aims To investigate long-term outcomes after endoscopic removal of malignant colorectal polyps (invasion confined to the submucosa).

Methods This single-center retrospective cohort study evaluated outcomes after endoscopic removal of malignant colorectal polyps between 2011 and 2017. Patients with prior histology suggestive of invasive adenocarcinoma were excluded. Residual disease rate and nodal metastases after secondary surgical resection, and local recurrence rate and distant metastases in case of surveillance-only strategy were investigated. Event rates for categorical and means for continuous variables with 95% confidence intervals were calculated.

Results Ninety-three lesions of 89 patients (mean age 68 years [65–70 years]; 45% female) were enrolled in our tertiary-care center. Mean post-polypectomy surveillance period was 4.0 years (3.5–4.5 years). Mean lesion size was 22.4 mm (19.8–25.0 mm), 42% located in the rectum. Proportion of pedunculated and non-pedunculated lesions was equal, with en bloc resection in 84% and 42%, respectively. Resection margins, depth of submucosal invasion, tumor differentiation, lymphovascular invasion, and budding was reported in 96.8%, 45.2%, 83.9%, 12.9%, and 5.4% of cases. Twenty-seven patients (30.3%) underwent secondary surgical resection with residual disease in 9/27 (33.3%) and nodal metastasis in 2/27 patients (7.4%). Surveillance-only strategy was chosen in the remaining 62 patients (69.7%). Two patients were lost to follow-up. Forty-four patients (73.3%) underwent surveillance colonoscopy (2.1 years [1.6–2.7 years] after polypectomy): 91%, 27% and 11% presented at 1-year, 3-year, and 5-year, respectively. Local recurrence was detected in one patient (1.7%) 22 months after polypectomy. Distant metastasis was found in 1/44 patient (2.3%) who underwent cross-sectional imaging.

Conclusions Residual disease rate in post-polypectomy surgical specimens was higher than previously reported. Adequate patient selection and polypectomy technique are necessary to obtain specimens allowing identification of unfavorable histologic features. In case of surveillance-only strategy, incidence of recurrence was low, but adherence to surveillance needs to be improved.