Significance of histologic criteria for the management of patients with malignant colorectal polyps and polypectomy

Background: The management of invasive cancer in colorectal polyps (malignant polyps) is controversial, particularly with regard to the different sets of histologic criteria for deciding whether malignant colorectal polyps should be treated by polypectomy alone or be followed by surgical resection. We report on the outcome of patients in accordance with the histologic assessment of their malignant polyps. Methods: Malignant polyps were defined as having favourable histology (free margin, grade I or II, and no angiolymphatic invasion) or unfavourable histology (no free margin, grade III, or angiolymphatic invasion). Malignant polyps with favourable histology were treated by endoscopic polypectomy alone, whereas further therapy was recommended for malignant polyps with unfavourable histology. Residual cancer in a resection specimen and local or metastatic recurrence during the follow-up period (mean, 60 months; range, 12-120) were defined as adverse outcome. Results: Thirty-seven malignant polyps were detected in 35 (0.5%) of 6605 patients. Five of these 35 patients were treated by primary bowel resection and analysed separately. in the other 30 patients the following unfavourable histologic signs were detected in 20 (62.5%) of 32 malignant polyps: no free margin in 16, grade III in 1, and angiolymphatic invasion in 3 polyps. Twelve polyps with favourable histology had no adverse outcome; in contrast, 5 of 20 polyps with unfavourable histology had an adverse outcome (P < 0.05). Conclusions: Locally excised malignant polyps without unfavourable histologic signs may not need further surgical treatment; for all other malignant polyps an ensuing bowel resection is recommended.