Risk for high-grade dysplasia or invasive carcinoma in colorectal flat adenomas in a Spanish population.
OBJECTIVE
to determine the frequency and malignancy risk of colonic flat adenomas among patients with colorectal polyps in a Spanish population.


METHODS
1300 consecutive colonoscopic examinations were reviewed; 640 polyps were detected and removed endoscopically in 298 patients. Chromoendoscopy with 0.2% indigo carmine was applied to clarify the macroscopical appearance of flat lesions. The following data was collected for flat and protruding polyps: size, location (proximal or distal to splenic flexure), histology (neoplastic or non neoplastic), high grade dysplasia (HGD) and submucosal invasive carcinoma (SIC) or beyond.


RESULTS
490 polyps (76.6%) were adenomas and 150 (23.4%) hyperplastic; 114 (23.3%) adenomas were flat (3 flat-depressed) whereas 376 (76.7%) were protruding. The diameter of flat and protruding adenomas was 9.2 +/- 7.9. mm and 7.0 +/- 5.9 mm, respectively (p < 0.001). A proximal location was more frequent for flat (63.1%) than for protruding adenomas (48.7%) (p = 0.003). The rate of HGD or SIC was significantly higher in flat than in protruding adenomas (7.0 vs 2.6%; p < 0.04). Two of the 3 flat-depressed lesions (both <or= 10 mm in diameter) were carcinomas (T1 and T2, respectively). Flat adenomas had an increased risk for HGD or SIC (OR = 2,7; CI, 1,04-7,04; p < 0.05).


CONCLUSIONS
In a Spanish population, flat adenomas represent nearly one quarter of all colorectal neoplastic polyps, their most frequent location being the right colon and they bear a higher risk of malignancy than protruding adenomas, especially for the flat depressed type.
Parra-Blanco
Adolfo
A
Department of Gastroenterology. University Hospital of the Canary Islands, La Laguna, Santa Cruz de Tenerife, Spain. parrablanco@hotmail.com
Gimeno-García
Antonio Z
AZ
Nicolás-Pérez
David
D
García
Candelaria
C
Medina
Carlos
C
Díaz-Flores
Lucio
L
Grosso
Begoña
B
Jiménez
Alejandro
A
Quintero
Enrique
E
D000236:Adenoma / Q000473:pathology*; D002277:Carcinoma / Q000473:pathology*; D003111:Colonic Polyps / Q000473:pathology*; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D012307:Risk Factors; D013030:Spain