Late Recurrence of Colorectal Carcinoma in Patients with Malignant Polyp and Risk Factors

Malignant polyps are polypoid lesions that appear benign endoscopically but harbor invasive adenocarcinoma microscopically. Patient with diagnosis of malignant polyp can be managed by surgical resection or endoscopic surveillance. Current literature on long term recurrence is sparse. A total of 76 patients with malignant polyp and follow-up period of over one year are included. Of these, 28 patients underwent endoscopic polypectomy followed by surveillance (group 1). Forty-eight patients underwent segmental colectomy (group 2). In group 1, three patients developed local recurrent pT3 adenocarcinoma (5.9 to 9.7 years) and one patient developed liver metastasis (7.3 years). One patient presented with malignant polyp in another segment of colon (4.0 years). Two of the malignant polyps with local recurrence do not have commonly reported high-risk features, including tumor ≤ 1 mm from resection margin, presence of lymphovascular invasion and high grade tumor, they had invasion depth of >4 mm and harbored a TP53 missense mutation. In group 2, during the follow-up period (1.0-21.8 years, median 9.3 years), none of the patients developed local recurrence. In this study, surveillance group had a local late recurrence rate of 10.7% versus no local recurrence in surgical resection group (0%). Our study shows that depth of invasion of over 4 mm in malignant polyp is a risk factor for late local recurrence if managed by endoscopic surveillance. Further study is needed to explore whether certain molecular alterations, such as TP53 mutation, is a risk factor for late recurrence.