Undetermined Margins After Colonoscopic Polypectomy for Malignant Polyps: The Need for Radical Resection.

The aim of the present study was to analyze the clinicopathological features of patients with colorectal cancer (CRC) who underwent radical operation after malignant polyp removal by colonoscopic procedure.Between 2009 and 2013, radical colorectal resection was performed in 50 patients with CRC after colonoscopic polypectomy.Nine cases (18%) had residual cancer. Lymph node (LN) metastasis was found in three cases (6.0%) and tumor deposit without LN metastasis (N1c) was found in two cases (4.0%). The indications for radical operation were an undetermined resection margin (23 cases), positive lateral margin (15 cases). Out of the nine cases with residual cancer, five cases had LN metastasis or tumor deposit without residual tumor in the main lesion. One-fourth of cases with an undetermined margin had residual cancer (six out of 23 cases), three of whom had stage III disease.Undetermined margins may be considered as an indication for additional radical operation.