Rate of residual disease after complete endoscopic resection of malignant colonic polyp.

Abstract

Following polypectomy, colectomy is performed selectively to ensure complete clearance of neoplasia. This study aimed to determine the risk factors associated with residual disease at colectomy following malignant polypectomy. This is a retrospective study. This investigation took place at a tertiary teaching cancer center. Consecutive patients undergoing polypectomy followed by colectomy from 1990 to 2007 were identified from a prospective database. Factors associated with residual disease at colectomy were associated with clinicopathologic features. Colectomy following polypectomy was performed in 143 patients: 127 with clear invasion of polyp submucosa (invasive disease), and 16 suspicious for submucosal invasion. Residual disease after colectomy was diagnosed in 27 (19%) of 143 patients. Disease was present in the colonic wall in 19 patients (13%): invasive in 16 (11%), and noninvasive in 3 (2.1%). Of the 16 patients with residual invasive disease at colectomy, 15 had clearly invasive disease at polypectomy and 1 was suspicious for invasive disease at polypectomy. Lymph node metastasis was noted in 10 (7.0%) patients. When analyzing patients with clearly invasive disease at polypectomy by margin status, residual invasive disease in the colon wall was noted in 8 of 50 (16%) with <1 mm (positive) polypectomy margin, 7 of 33 (21%) with indeterminate polypectomy margin, and 0 of 44 with ≥1 mm (negative) polypectomy margin (p = 0.009). Nodal metastasis was associated with the presence of lymphovascular invasion (p = 0.01). This study is limited by its retrospective nature and selection bias. Following malignant polypectomy, colectomy should be considered in medically fit patients if the polypectomy margin is positive (≤1 mm) or unknown, or if lymphovascular invasion is present.