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

Background: A colorectal neoplasm that spreads superficially over the mucos a is known as a laterally spreading tumor. The clinicopathologic features o f these large lesions and the efficacy and safety of endoscopic mucosal res ection (EMR) were studied retrospectively. Methods: Surgically or endoscopically resected laterally spreading tumors l arger than 20 mm in diameter were studied. Lesions were divided into 2 macr oscopic subtypes: F-type, composed of superficially spreading lesions with a fat and smooth surface, and G-type, composed of superficially spreading a ggregates of nodules that form relatively flat, broad-based lesions with gr anulonodular end uneven surfaces. Results: 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 wit h 78 of these lesions were followed postoperatively for 60.8 +/- 20.1 month s. The rate of local recurrence of endoscopically treated tumors as determi ned at colonoscopy was 7.4% (6/78), These lesions were completely resected endoscopically, Distant metastases were not detected. Thirteen (16.0%) pati ents had local bleeding after EMR that was stopped endoscopically. Microper foration of the colonic wall as a result of EMR was diagnosed in 1 (1.2%) o f 81 cases. Conclusions: Laterally spreading tumors larger than 20 mm, especially those of the G-type, have a low rate of invasion despite their relatively large sire. The F-type lesion has a higher malignant potential than the G-type. E MR is an effective and safe treatment for the large laterally spreading tum or.