Indications of endoscopic polypectomy for rectal carcinoid tumors and clinical usefulness of endoscopic ultrasonography

PURPOSE: This study was designed to define the indications of endoscopic polypectomy for rectal carcinoid tumors and evaluate the diagnostic value of endoscopic ultrasonography. METHODS: A total of 66 rectal carcinoid tumors treated at our hospital were analyzed histopathologically to clarify risk factors for metastasis. The depth of invasion was determined for 52 lesions examined by cndoscopic ultrasonography, and the value of endoscopic ultrasonography for deciding whether a lesion is indicated for endoscopic polypectomy was assessed. RESULTS: None of the 57 lesions measuring less than or equal to 10 mm in diameter invaded the muscularis propria or had metastasis. Of nine lesions with a diameter of 11 mm, five invaded the muscularis propria and four had metastasis. A central depression was found in three of the lesions with metastasis. The depth of invasion of 49 lesions examined by endoscopic ultrasonography was limited to the submucosa; 3 lesions invaded the muscularis propria. The depth of invasion of all lesions was correctly diagnosed by endoscopic ultrasonography. Ninety-six percent of the lesions that had subnulcosal invasion with narrowing of the tipper two-thirds of the third layer (submucosa) as evaluated by endoscopic ultrasonography could be completely resected by endoscopic polypectomy. CONCLUSIONS: Rectal carcinoid tumors that satisfy the following three conditions are indicated for local resection, including endoscopic polypectomy: a maximum diameter of less than or equal to 10 mm, no invasion of the muscularis propria, and no depression or ulceration in the lesion. Endoscopic ultrasonography also is useful for estimating the depth of invasion of rectal carcinoid tumors and for determining whether endoscopic polypectomy is indicated.