Original Articles
Clinicopathologic features and endoscopic treatment of superficially spreading colorectal neoplasms larger than 20 mm,☆☆

Presented in part at the annual meeting of the American Society for Gastrointestinal Endoscopy, May 1998, Washington, D.C.
https://doi.org/10.1067/mge.2001.115729Get rights and content

Abstract

Background: 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. Methods: 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. 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 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. Conclusions: 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. (Gastrointest Endosc 2001;54:62-6.)

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Materials and methods

The clinical and pathologic features of 120 surgically or endoscopically resected LSTs (carpet-type creeping tumor)1, 8, 9 larger than 20 mm in maximum diameter were studied (32 adenomas, 70 in situ carcinomas and 18 submucosally invasive carcinomas). Informed consent was obtained from all patients before each procedure. The lesions were divided into 2 subtypes based on the macroscopic surface appearance at endoscopy. F-type lesions had a flat, smooth surface and were low in height (Fig. 1).

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Results

Of the 120 LSTs, 33 were F-type and 87 were G-type lesions. Four colonoscopists differentiated between F- and G-type LSTs during colonoscopy; there was no disagreement as to lesion type among the 4 colonoscopists. In addition, all colonoscopists agreed as to the diagnosis for all lesions on review of archival images obtained during colonoscopy. Thus, there were no instances of inter- or intraobserver variability.

G-type lesions were significantly larger than F-type lesions (33.3 ± 11.4 mm versus

Discussion

The large superficial spreading neoplasm in the colon or rectum, termed LST, has been recognized as an important precursor of advanced colorectal carcinoma. Large numbers of LSTs have been reported and their clinical significance discussed.1, 2, 7, 8 LST was divided into F- and G-types based on detailed observation during chromoendoscopy with indigo carmine dye spraying. Although there are several reports concerning endoscopic excision of giant colorectal polyps,14, 15, 16, 17, 18 there have

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Reprint requests: Shinji Tanaka, MD, PhD, Department of Endoscopy, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551, Japan.

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Gastrointest Endosc 2001;54:62-6

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