Colon polyps may be classified into two main groups: neoplastic and non-neoplastic. Neoplastic polyps consist of adenomas and carcinomas, with adenomas being divided into three groups (tubuler, tubulovillous and villous) histopathologically. The non-neoplastic group include hyperplastic polyps, juvenile polyps, Peutz Jeghers polyps and inflammatory polyps (
3).
Adenomas are considered to be precancerous lesions. Although the incidence of adenomas in the general population ranges from 4-10% (4), it increases with age (5,6).
There is a positive corelation between the size of the adenoma and risk of the carcinoma development. The risk of malignant degeneration is higher in polyps greater than 1 cm in size.
In general, the location of adenomas is similar to carcinomas. Several surgical and colonoscopic series have shown that adenomas tend to be located in the rectum, sigmoid colon and the left colon. In our study, the majority (76.7%) of the adenomas were at the splenic flexure and distal colon. 12.1% were at the transverse colon and only 10.8% at the hepatic flexure and proximal to the hepatic flexure.
Histopathological examination of the polyps revealed that 77.5% were tubular, 16.7% tubulovillous and 5.7% villous. In the literature, these rates are reported as 60-80%, 15-25% and 3-10% respectively (7,8). Our findings conformed with the ratios indicated in literature. In another study from Turkey, the rate of villous adenoma was determined as 15.82% and that of tubuler adenoma 55.07% (9).
In our series, malignant degeneration was detected in 32 cases (9.1%), which was similar to the literature, where the frequency of carcinoma in situ and invasive cancer is reported as 5-10% (7,8). In our study, 78 of 350 polyps where polypectomy and histopathological examination were performed were hyperplastic, which are known to be non-neoplastic and benign lesions. The risk of cancer development in hyperplastic polyps is very low.
However, in recent years it has been suggested that hyperplastic polyps can be indicators of adenomatous polyps (10-11). In another retrospective study from Turkey, 31 hyperplastic polyps (31.6%) amongst 228 colonoscopically removed lesions observed in 22 patients (27.2%) were found to occur along with proximal synchronous adenomas. It was concluded that hyperplastic polyps may have clinical significance as marker lesions for adenomas elsewhere in the colon (12). In our study, 78 hyperplastic polyps were found in the splenic flexure, 65 in the distal colon (83%), eight (10.2%) in the transverse colon and five (6.4%) in the hepatic flexura and the proximal colon. Our findings are similar to those of other studies (9,12).
In the 22 cases followed up by the therapeutic endoscopy team, the recurrence rates of polyps were found to be 59% (13 cases) and 27.2 % (six cases) in the first and second six month periods respectively. In the literature, the recurrence rate for the first year is reported to be 5-15% (13-15). However, in some reports these rates are as high as 55% (16). It is considered that the high rate of 59% for the first six months in this study was not related to real recurrence but was probably due to polyps missed on initial colonoscopy.Further studies with a larger number of cases may produce more accurate results.
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