Clinicopathologic features and endoscopic treatment of superficially spreading colorectal neoplasms larger than 20 mm

A colorectal neoplasm that spreads superficially over the mucosa is known as a laterally spreading tumor. The clinicopathologic features of these large lesions and the efficacy and safety of endoscopic mucosal resection (EMR) were studied retrospectively.

Surgically or endoscopically resected laterally spreading tumors larger than 20 mm in diameter were studied. Lesions were divided into 2 macroscopic subtypes: F-type, composed of superficially spreading lesions with a flat and smooth surface, and G-type, composed of superficially spreading aggregates of nodules that form relatively flat, broad-based lesions with granulonodular and uneven surfaces.

Thirty-three lesions were of the F-type and 87 the G-type. G-type (mean +/- SD, 35.3 +/- 11.4 mm) lesions were significantly larger (p < 0.01) than F-type (26.0 +/- 7.2 mm) lesions. F-type lesions had a significantly higher frequency of invasive cancer (27.2%) than G-types (10.3%)(p < 0.05). Of the 120 lesions, 81 (67.5%) were resected endoscopically. Patients with 78 of these lesions were followed postoperatively for 60.8 +/- 20.1 months. The rate of local recurrence of endoscopically treated tumors as determined at colonoscopy was 7.4% (6/78). These lesions were completely resected endoscopically. Distant metastases were not detected. Thirteen (16.0%) patients had local bleeding after EMR that was stopped endoscopically. Microperforation of the colonic wall as a result of EMR was diagnosed in 1 (1.2%) of 81 cases.

Laterally spreading tumors larger than 20 mm, especially those of the G-type, have a low rate of invasion despite their relatively large size. The F-type lesion has a higher malignant potential than the G-type. EMR is an effective and safe treatment for the large laterally spreading tumor.