A J Aldridge1, J N Simson. 1. Department of Surgery, St Richard's Hospital, Chichester, UK.
Abstract
OBJECTIVE: To define the relative risk of malignant transformation in colorectal adenomas less than 10 mm in diameter. DESIGN: Prospective study. SETTING: District general hospital, UK. SUBJECTS AND MATERIALS: 1228 polyps detected endoscopically in 445 patients over the 10-year period 1989-1999. MAIN OUTCOME MEASURES: Site, size, histological type and dysplastic grade of polyp. RESULTS: 657 of the 1228 polyps were adenomas: 281 (43%) tubular, 339 (51%) tubulovillous and 37 (6%) villous. In the 357 adenomas less than 10 mm in diameter, 11 (3%) were severely dysplastic and 2 carcinomas were detected, though neither was less than 5 mm in size. The relative risk of malignancy or severe dysplasia in adenomas of 10 mm or more compared with those of less than 10 mm was 3.8 (p < 0.0001). CONCLUSIONS: Although severe dysplasia and malignancy do occur in adenomas less than 10 mm in size, they are rare in lesions of less than 5 mm. We recommend routine destruction of all polyps 5 mm or more in size, though it is not essential to remove those of less than 5 mm if they are kept under surveillance.
OBJECTIVE: To define the relative risk of malignant transformation in colorectal adenomas less than 10 mm in diameter. DESIGN: Prospective study. SETTING: District general hospital, UK. SUBJECTS AND MATERIALS: 1228 polyps detected endoscopically in 445 patients over the 10-year period 1989-1999. MAIN OUTCOME MEASURES: Site, size, histological type and dysplastic grade of polyp. RESULTS: 657 of the 1228 polyps were adenomas: 281 (43%) tubular, 339 (51%) tubulovillous and 37 (6%) villous. In the 357 adenomas less than 10 mm in diameter, 11 (3%) were severely dysplastic and 2 carcinomas were detected, though neither was less than 5 mm in size. The relative risk of malignancy or severe dysplasia in adenomas of 10 mm or more compared with those of less than 10 mm was 3.8 (p < 0.0001). CONCLUSIONS: Although severe dysplasia and malignancy do occur in adenomas less than 10 mm in size, they are rare in lesions of less than 5 mm. We recommend routine destruction of all polyps 5 mm or more in size, though it is not essential to remove those of less than 5 mm if they are kept under surveillance.