Colorectal Cancer Incidence and Mortality After Removal of Adenomas During Screening Colonoscopies.

BACKGROUND & AIMS: Recommendation of surveillance colonoscopy should be based on risk of colorectal cancer and death after adenoma removal. We aimed to develop a risk classification system based on colorectal cancer incidence and mortality following adenoma removal. METHODS: We performed a multicenter population-based cohort study of 236,089 individuals (median patient age, 56 years; 37.8% male) undergoing screening colonoscopies with adequate bowel cleansing and cecum intubation at 132 centers in the Polish National Colorectal Cancer Screening Program, from 2000 through 2011. Subjects were followed for a median 7.1 years and information was collected on colorectal cancer development and death. We used recursive partitioning and multivariable Cox models to identify associations between colorectal cancer risk and patient and adenoma characteristics (diameter, growth pattern, grade of dysplasia, and number of adenomas). We developed a risk classification system based on standardized incidence ratios, using data from the Polish population for comparison. The primary endpoints were colorectal cancer incidence and colorectal cancer death. RESULTS: We identified 130 colorectal cancers in individuals who had adenomas removed at screening (46.5 per 100,000 person-years) vs 309 in individuals without adenomas (22.2 per 100,000 person-years). Compared with individuals without adenomas, adenomas ≥20 mm in diameter and high-grade dysplasia were associated with increased risk of colorectal cancer (adjusted hazard ratios 9.25; 95% confidence interval [CI] 6.39-13.39, and 3.58; 95% CI 1.96-6.54, respectively). Compared with the general population, colorectal cancer risk was higher or comparable only for individuals with adenomas ≥20 mm in diameter (standardized incidence ratio [SIR] 2.07; 95% CI 1.40-2.93) or with high-grade dysplasia (SIR 0.79; 95% CI 0.39-1.41), whereas for individuals with other adenoma characteristics the risk was lower (SIR 0.35; 95% CI 0.28-0.44). We developed a high-risk classification based on adenoma size ≥20 mm or high-grade dysplasia (instead of the current high-risk classification cutoff of ≥3 adenomas or any adenoma with villous growth pattern, high-grade dysplasia, or ≥10 mm in diameter). Our classification system would reduce the number of individuals classified as high-risk and requiring intensive surveillance from 15,242 (36.5%) to 3980 (9.5%), without increasing risk of colorectal cancer in patients with adenomas (risk difference per 100,000 person-years, 5.6; 95% CI -10.7 to 22.0). CONCLUSIONS: Using data from the Polish National Colorectal Cancer Screening Program, we developed a risk classification system that would reduce the number of individuals classified as high risk and require intensive surveillance more than 3-fold, without increasing risk of colorectal cancer in patients with adenomas. This system could optimize the use of surveillance colonoscopy.

Increased Rate of Adenoma Detection Associates With Reduced Risk of Colorectal Cancer and Death.

BACKGROUND & AIMS: The quality of endoscopists' colonoscopy performance is measured by adenoma detection rate (ADR). Although ADR is associated inversely with interval colorectal cancer and colorectal cancer death, the effects of an increasing ADR have not been shown. We investigated whether increasing ADRs from individual endoscopists is associated with reduced risks of interval colorectal cancer and subsequent death. METHODS: We performed a prospective cohort study of individuals who underwent a screening colonoscopy within the National Colorectal Cancer Screening Program in Poland, from January 1, 2004, through December 31, 2008. We collected data from 146,860 colonoscopies performed by 294 endoscopists, with each endoscopist having participated at least twice in annual editions of primary colonoscopy screening. We used annual feedback and quality benchmark indicators to improve colonoscopy performance. We used ADR quintiles in the whole data set to categorize the annual ADRs for each endoscopist. An increased ADR was defined as an increase by at least 1 quintile category, or the maintenance of the highest category in subsequent screening years. Multivariate frailty models were used to evaluate the effects of increased ADR on the risk of interval colorectal cancer and death. RESULTS: Throughout the enrollment period, 219 endoscopists (74.5%) increased their annual ADR category. During 895,916 person-years of follow-up evaluation through the National Cancer Registry, we identified 168 interval colorectal cancers and 44 interval cancer deaths. An increased ADR was associated with an adjusted hazard ratio for interval colorectal cancer of 0.63 (95% confidence interval [CI], 0.45-0.88; P = .006), and for cancer death of 0.50 (95% CI, 0.27-0.95; P = .035). Compared with no increase in ADR, reaching or maintaining the highest quintile ADR category (such as an ADR > 24.56%) decreased the adjusted hazard ratios for interval colorectal cancer to 0.27 (95% CI, 0.12-0.63; P = .003), and 0.18 (95% CI, 0.06-0.56; P = .003), respectively. CONCLUSIONS: In a prospective study of individuals who underwent screening colonoscopy within a National Colorectal Cancer Screening Program, we associated increased ADR with a reduced risk of interval colorectal cancer and death.