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Five-year risk for advanced colorectal neoplasia after initial colonoscopy according to the baseline risk stratification: a prospective study in 2452 asymptomatic Koreans
  1. Su Jin Chung1,
  2. Young Sun Kim1,
  3. Sun Young Yang1,
  4. Ji Hyun Song1,
  5. Donghee Kim1,
  6. Min Jung Park1,
  7. Sang Gyun Kim2,
  8. In Sung Song2,
  9. Joo Sung Kim2
  1. 1Department of Internal Medicine, Healthcare Research Institute, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, South Korea
  2. 2Department of Internal Medicine, Liver Research Institute, Seoul National University College of Medicine, Seoul, South Korea
  1. Correspondence to Joo Sung Kim, Department of Internal Medicine, Liver Research Institute, Seoul National University College of Medicine, 28 Yongon-Dong, Chongno-Gu, Seoul 110-744, South Korea; jooskim{at}


Objective Postpolypectomy surveillance guidelines for colorectal cancer introduced the concept of ‘risk stratification’; however, few studies have been conducted for validation of its usefulness. The aim of this study was to assess the 5-year incidence of advanced neoplasia recurrence based on the risk stratification scheme of the guidelines and to identify its risk factors.

Methods A prospective study of surveillance colonoscopy after screening colonoscopy was carried out at the Seoul National University Hospital Healthcare System Gangnam Center. 3803 asymptomatic Koreans aged 50–69 were enrolled prospectively and 5-year cumulative adenoma rates were analysed according to three risk groups: normal (no baseline adenoma), low-risk (1–2 adenomas <10 mm) and high-risk (an advanced adenoma or ≥3 adenomas) groups. The RR was computed by HR using Cox proportional regression after multivariate adjustments. The primary outcome was the 5-year cumulative rate of recurrent advanced adenoma in each risk category and the secondary outcome was its predictive factors.

Results Among 3803 subjects enrolled between 2003 and 2005, 2452 were followed-up within 5 years: 1242, 671 and 539 in the normal, low-risk and high-risk groups, respectively. Compared with the normal group, the low-risk group had a sufficiently low 5-year incidence and did not show an increased risk for subsequent advanced adenoma (2.4% vs 2.0%, HR=1.14, 95% CI 0.61 to 2.17). Conversely, a significantly higher 5-year rate (12.2%) and early recurrence (4.6, 7.4 and 9.6% at 1, 2 and 3 years) of advanced adenoma were revealed in the high-risk group. Among various patients and adenoma characteristics, only high-risk adenoma (HR=5.95, 95% CI 3.66 to 9.68) along with a number of ≥3 (HR=3.06, 95% CI 1.51 to 6.57) and size ≥10 mm (HR=3.02, 95% CI 1.80 to 5.06) were independent predictors.

Conclusions The surveillance interval for low-risk patients could be extended beyond 5 years. Colonoscopic surveillance should be targeted to high-risk patients, and 3-year follow-up after initial polypectomy may be appropriate.

  • Colorectal neoplasia
  • surveillance
  • colonoscopy
  • recurrence
  • risk factor

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  • Competing interests None.

  • Patient consent Obtained.

  • Ethics approval This study was conducted with the approval of the Seoul National University College of Medicine/Seoul National University Hospital Institutional Review Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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