Introduction Colonoscopic screening for colorectal cancer (CRC) reduces CRC-associated mortality; however, there is some evidence that this effect applies to mainly left-sided, rather than right-sided, CRC. It is postulated that this might be because polyps with advanced pathology are smaller in the right colon and therefore more easily missed (Gupta et al Clin Gastroenterol Hepatol 2012; 10:1395–1401). Our aim was to evaluate the relationship between the size and location of polyps with advanced neoplasia in a population undergoing bowel screening in North-East Scotland.
Methods Analysis of prospectively collected data collected for all screening colonoscopies performed in NHS Grampian region between January 2009 and January 2011. Subjects who had complete colonoscopy were included in the study. Lesions in the rectum, sigmoid or descending colon were considered left sided and lesions proximal to the splenic flexure considered right sided. Advanced neoplastic lesions (ANLs) were defined as polyps with cancer, high grade dysplasia or tubulovillous histology. Lesion size was defined as ≥1cm or < 1 cm
Results Of the total 1415 subjects undergoing screening colonoscopy during the 2 year period, 1320 (93.3%) had a complete colonoscopy and were included in the analysis. Of these, 606 (45.9%) subjects had a total of 1366 polyps; of these, 213 (35%) subjects had ANLs. Median patient age was 64yrs, and 157 (74%) were males. ANLs were located in the left colon in 169 (79.3%) subjects, in the right colon in 31 (14.6%) of subjects, and in both sides in 13 (6.1%) subjects. There was no significant difference between the proportion of subjects with small ANLs (< 1 cm size) in the right colon (n = 3, 9.7%) compared to the left colon (n = 24, 14.2%; Fisher’s exact test).
Conclusion In subjects undergoing bowel cancer screening in North-East Scotland, small ANLs were not more common in the right colon. Further studies are required to clarify the pathogenesis of right-sided colonic cancer.
Disclosure of Interest None Declared.
Gupta et al. Clin Gastroenterol Hepatol 2012; 10:1395–1401
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