MANAGEMENT OF EARLY PEDUNCULATED COLORECTAL CANCER

Abstract

The histopathologic characteristics of early pedunculated colorectal cancer often include a disrupted muscularis mucosae. Distinguishing such cases from other macroscopic types by measuring submucosal (SM) invasion depth is important in determining the treatment strategy.

When the muscularis mucosae can be identified, the depth of SM invasion is calculated as the distance between the deeper edge of the muscularis mucosae and the point of deepest invasion. When the muscularis mucosae cannot be identified, the depth of SM invasion is measured as the distance between the surface of the tumor and the point of deepest invasion. In polypoid tumors (0-Ip) with disrupted muscularis mucosae, the depth of SM invasion is considered the distance between the point of deepest invasion and the reference line (the fictitious line separating the tumor head and the pedicle). However, there is some discrepancy in these identification and estimation methods of the muscularis mucosae, even among pathologists.

Nonetheless, according to the current colorectal cancer treatment guidelines, endoscopic treatment is indicated if cTis or cT1a (SM invasion less than 1,000μm) is diagnosed, and surgical treatment including lymphadenectomy is recommended if cT1b (SM invasion deeper than 1,000μm) is diagnosed. However, some reports suggest that the invasion depth of protruded lesions, including early pedunculated colorectal cancer, is lesser than that of superficial lesions. It also reported that the risk of lymph node metastasis in pedunculated T1b cancer is lower than that in non-pedunculated T1b cancer. As pedunculated lesions are easier to endoscopically resect en bloc than other macroscopic lesions, endoscopic treatment is often performed first. Further research is needed to distinguish pedunculated from non-pedunculated lesions, including endoscopic diagnosis, indications for treatment, and methods to evaluate SM invasiveness.