BACKGROUND Retrospective evaluation of colonoscopy reports in persons with proximal colorectal cancer (PCRC) reported in 5 studies has consistently shown that persons with cancer proximal to the splenic flexure have no neoplasia distal to the splenic flexure in 75% of cases. Thus the capacity of screening flexible sigmoidoscopy (FS) to detect proximal cancer indirectly through identification of distal adenomas which would lead to colonoscopy is limited (Lemmel et al, Gastrointest Endosc 1996;44:109-11). However, the effectiveness of colonoscopic clearing and the percent of patients with positive family histories in these studies is unknown. The latter has importance because persons with a positive family history may be more likely to have proximal cancers. AIM: To determine the limits of effectiveness of FS screening in average-risk persons with PCRC by prospective colonoscopy and left colon clearing in PCRC patients and prospective collection of family histories. METHODS: Multicenter prospective colonoscopy of consecutively identified cases of PCRC and collection of family histories. RESULTS: Thirty-nine patients with PCRC have been identified thus far, of whom 5 reported one or more first degree relatives with cancer and 34 did not have such a history (average-risk). Proximal location of CRC was confirmed by surgery in 38 cases. Of those with a positive family history, 2 (40%) had one or more adenomatous polyps distal to the splenic flexure. Of the 34 without a positive family history, 14 (41%) had ≥ 1 adenoma distal to the splenic flexure. Of these, 8 (24%) had ≥ 1 adenoma distal to the splenic flexure that was ≥ 1 cm in size. Two others had cancer. SUMMARY: Of average-risk persons with PCRC, 47% had neoplasia distal to the splenic flexure and 29% had advanced neoplasia (adenoma ≥ 1 cm or cancer). CONCLUSION: Prospective determination of distal colonoscopic findings indicates that screening flexible sigmoidoscopy would be negative in over half of patients with PCRC. However, this percent is lower than reported in retrospective studies. When distal neoplasia is present it is usually advanced, supporting recent findings that advanced adenomas in the distal colon are more likely than small distal adenomas to be associated with advanced proximal neoplasia.
|Original language||English (US)|
|State||Published - Dec 1 1997|
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging