Original article
Chromoendoscopic Colonoscopy for Detecting Preneoplastic Lesions in Hereditary Nonpolyposis Colorectal Cancer Syndrome

https://doi.org/10.1016/S1542-3565(05)00403-9Get rights and content

Background & Aims: In hereditary nonpolyposis colorectal cancer (HNPCC) syndrome, flat and small adenomas are particularly prone to malignant transformation but might be missed by standard colonoscopy. We prospectively studied the diagnostic yield of high-resolution colonoscopy coupled with chromoendoscopy for preneoplastic and neoplastic colorectal lesions in patients with HNPCC syndrome. Methods: Thirty-six consecutive asymptomatic patients (mean age, 42 years) belonging to HNPCC families and receiving genetic counseling were enrolled in this prospective study. Colonoscopy was performed in 2 steps. Conventional colonoscopy was performed first, followed by a second colonoscopy with chromoendoscopy with indigo carmine (.4%) dye sprayed onto the entire proximal colon. Results: Conventional colonoscopy identified 25 lesions (mean size, 4 ± 3 mm) in 13 patients. Seven lesions, detected in 5 patients, were adenomas, 3 of which were located in the proximal colon. Chromoendoscopy identified additional 45 lesions (mean size, 3 ± 1 mm) in 20 patients; most of these lesions were flat and hyperplastic. Eleven additional adenomas were detected in the proximal colon of 8 patients, and 8 of these 11 lesions were flat. The use of chromoendoscopy significantly increased the detection rate of adenomas in the proximal colon, from 3 of 33 patients to 10 of 33 patients (P = .045). Conclusion: Relative to conventional colonoscopy, high-resolution colonoscopy with chromoendoscopy markedly improves the detection of adenomas in patients with HNPCC syndrome and might help to prevent colorectal carcinoma in these patients with a very high risk of colorectal cancer.

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Patients

The International Collaborative Group on HNPCC recommends that patients meeting the Amsterdam criteria and/or with a mutated germinal mismatch repair (MMR) gene undergo colonoscopy every 2 years, starting at the age of 25 years.6 We conducted a prospective study of consecutive asymptomatic individuals belonging to families meeting the Amsterdam criteria for HNPCC syndrome. The patients received genetic counseling and were referred for colonoscopy after giving their informed consent, in keeping

Results

A total of 36 patients met the inclusion criteria and were enrolled in the study between April 2001 and June 2003. None of the screened patients declined to take part in the study.

The baseline characteristics of the 36 patients are shown in Table 1. Eighteen patients included in our study had a confirmed germline MMR gene mutation. Among them, 12 patients had a germline mutation of MSH2 gene and 6 a germline mutation of MLH1 gene. No germline MMR gene mutation was detected in the 18 other

Discussion

This study shows that chromoendoscopy with indigo carmine significantly improves the detection of preneoplastic adenomatous lesions in the proximal colon of patients with HNPCC syndrome. In the largest series of HNPCC families participating in a surveillance program, colonoscopic screening at 3-year intervals has reduced the colorectal cancer rate by at least 60%, prevented colorectal cancer deaths, and reduced overall mortality by about 65%.3 However, colorectal cancer can occur with a few

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