Long-term Risk of Colorectal Cancer and Related Deaths After a Colonoscopy With Normal Findings

Baseline Colonoscopy Findings Associated With 10-Year Outcomes in a Screening Cohort Undergoing Colonoscopy Surveillance

BACKGROUND & AIMS

Few studies have evaluated long-term outcomes of ongoing colonoscopic screening and surveillance in a screening population. We aimed to determine the 10-year risk for advanced neoplasia (defined as adenomas ≥10mm, adenomas with villous histology or high-grade dysplasia, or colorectal cancer [CRC]) and assessed whether baseline colonoscopy findings were associated with long-term outcomes.

METHODS

We collected data from the Department of Veterans Affairs Cooperative Studies Program Study on 3121 asymptomatic veterans (50-75 years old) who underwent a screening colonoscopy from 1994 through 1997 at 13 medical centers and were then followed for 10 years or until death. We included 1915 subjects with at least 1 surveillance colonoscopy and estimated cumulative incidence of advanced neoplasia by Kaplan-Meier curves. We then fit a longitudinal joint model to estimate risk of advanced neoplasia at each subsequent examination after baseline, adjusting for multiple colonoscopies within individuals.

RESULTS

Through 10 years of follow-up, there were 146 individuals among all baseline colonoscopy groups found to have at least 1 incident advanced neoplasia. The cumulative 10-year incidence of advanced neoplasia was highest among those with baseline CRC (43.7%; 95% CI 13.0%-74.4%), followed by those with baseline advanced adenoma (AA) (21.9%; 95% CI 15.7-28.1). The cumulative 10-year incidence of advanced neoplasia was 6.3% (95% CI 4.1%-8.5%) and 4.1% (95% CI 2.7%-5.4%) for baseline 1 to 2 small adenomas (<1cm, and without villous histology or high-grade dysplasia) and no neoplasia, respectively (log-rank P = .10). After adjusting for prior surveillance, the risk of advanced neoplasia at each subsequent examination was not significantly increased in veterans with 1 or 2 small adenomas at baseline (odds ratio 0.96; 95% CI 0.67-1.41) compared with veterans with no baseline neoplasia.

CONCLUSIONS

Baseline screening colonoscopy findings associate with advanced neoplasia within 10 years. Individuals with only 1 or 2 small adenomas at baseline have a low risk of advanced neoplasia over 10 years. Alternative surveillance strategies, could be considered for these individuals.

Does Colon Polyp Surveillance Improve Patient Outcomes?

Colon polyp surveillance now accounts for 25% of all colonoscopies performed. The evidence that colonoscopy surveillance reduces colorectal cancer (CRC) incidence or mortality is weak. The biology of the baseline lesions and quality of the baseline exam are two primary factors contributing to post-colonoscopy CRC. Prior recommendations for surveillance were based largely on the likelihood that patients with adenomas would develop advanced adenomas, a surrogate for CRC. There is now evidence that baseline colonoscopy findings are strongly associated with the risk of incidence or death from CRC. This evidence provides a basis for updated evidence-based recommendations for surveillance. In addition, there is also growing evidence that the quality of the baseline exam is an important predictor of the likelihood of developing post-colonoscopy CRC.

Risk Factors for Colorectal Cancer in Korea: A Population-Based Retrospective Cohort Study

Purpose

The incidence of colorectal cancer in Korea has recently increased, making it the second most common cancer in men and the third most common cancer in women. Risk factors for colorectal cancer have been studied worldwide, but risk factors specific for the Korean population have not been established. In this study, we investigated incidence trends and risk factors of colorectal cancer in Korea.

Methods

A total of 8,846,749 subjects were included. Colorectal cancer incidence was investigated using Korea National Health Insurance Service claim data from 2004 to 2014. Colorectal cancer diagnoses were obtained by evaluating colorectal cancer diagnostic codes and the cancer registry for cost sharing. Risk factor identification for colorectal cancer was obtained from National Health Examination data from 2004 to 2005. Cox proportional hazard model statistical analysis was used to determine risk factors of colorectal cancer.

Results

The incidence of colorectal cancer gradually increased from 2006 to 2014 (from 45.4/100,000 to 54.5/100,000). There was a predominance among men (1.47:1), but incidence trends were similar in both sexes. Old age, high body mass index, and no history of colonoscopy were identified as risk factors in both sexes. High fasting blood glucose, familial history of cancer, frequent alcohol intake, and current smoker were identified as risk factors, especially in men.

Conclusion

The incidence of colorectal cancer has been increasing in Korea. Colonoscopy screening was a protective factor for colorectal cancer, and active use of colonoscopy may reduce incidence. Early diagnosis and care are important, particularly for the high-risk group.

Reviewing the Evidence that Polypectomy Prevents Cancer

Colonoscopic polypectomy is fundamental to effective prevention of colorectal cancer. Polypectomy reduces colorectal cancer incidence and mortality by altering the natural history and progression of precancerous precursor polyps. Epidemiologic data from the United States, where colorectal cancer rates have been steadily declining in parallel with screening efforts, provide indisputable evidence about the effectiveness of polypectomy. Randomized controlled trials of fecal occult blood tests and flexible sigmoidoscopy, and observational colonoscopy studies, provide additional support. Longitudinal studies have shown variable levels of protection after polypectomy, highlighting the central importance of high quality and adequate surveillance of higher-risk patients.