Clinicopathologic characteristics and malignant potential of colorectal flat neoplasia compared with that of polypoid neoplasia.
OBJECTIVE
Because of their potential for malignancy, flat colorectal neoplasias are a current topic of debate. This study was designed to investigate the clinicopathologic features of flat neoplasia and to compare them with those of polypoid neoplasia, as well as to identify the determinants of malignant transformation of both flat and polypoid colorectal neoplasia.


METHODS
A prospective, cross-sectional study of 3,360 patients diagnosed with adenomas via total colonoscopy and polypectomy was performed at 11 tertiary medical centers between July 2003 and July 2004. In this study, potential risk factors for malignant transformation were analyzed. If multiple adenomas were identified, then only the adenoma with the most advanced degree of histology was recorded for the patient.


RESULTS
Of a total of 3,360 neoplasias identified, we found that the incidence of flat and polypoid neoplasias were 207 (6.2 percent) and 3,153 (93.8 percent), respectively. Patients with flat neoplasias tended to be older (59.6 vs. 57.1, P < 0.01), with the neoplasia located more frequently in the right colon than polypoid neoplasias (49.3 percent vs. 32 percent, P < 0.01). The incidence of high-grade dysplasia or cancer in flat neoplasias was similar to that of polypoid neoplasias (5.4 percent vs. 4.6 percent, P = 0.36). Multivariate analysis revealed that a size of > or =11 mm (odds ratio, 6.8; 95 percent confidence interval, 4.8-9.7) and location in the left colon (odds ratio, 1.6; 95 percent confidence interval, 1.1-2.4) were significant determinants for the malignancy potential of colonic neoplasias.


CONCLUSIONS
The clinicopathologic indices for the propensity of malignant transformation in colorectal neoplasias were a size > or =11 mm and location in the left colon rather than flat gross morphology.
Park
Dong Hun
DH
Department of Internal Medicine and Institute of Lifelong Health, Yonsei University, Wonju College of Medicine, 162 Ilsan-dong, Wonju, South Korea.
Kim
Hyun Soo
HS
Kim
Won Ho
WH
Kim
Tae Il
TI
Kim
Young Ho
YH
Park
Dong Il
DI
Kim
Hyo Jong
HJ
Yang
Suk-Kyun
SK
Byeon
Jeong-Sik
JS
Lee
Moon Sung
MS
Chung
Il Kwun
IK
Jung
Sung Ae
SA
Jeen
Yoon Tae
YT
Choi
Jai Hyun
JH
Choi
Hwang
H
Han
Dong Soo
DS
D000236:Adenoma / Q000453:epidemiology / Q000473:pathology*; D000368:Aged; D001706:Biopsy; D002471:Cell Transformation, Neoplastic; D003111:Colonic Polyps / Q000453:epidemiology / Q000473:pathology*; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000473:pathology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011230:Precancerous Conditions / Q000453:epidemiology / Q000473:pathology*; D011446:Prospective Studies