Early-Age Onset Colorectal Neoplasia in Average-Risk Individuals Undergoing Screening Colonoscopy: A Systematic Review and Meta-Analysis

Background & Aims: Incidence and mortality associated with early-age onset colorectal cancer (EAO-CRC) is increasing, prompting professional society recommendations to lower the screening age in average-risk individuals. The yield of screening individuals younger than 50 years is not known. Methods: A systematic review of 3 databases from inception through July 2020 was performed in all languages that reported colonoscopy findings in average-risk individuals younger than 50 years. The primary outcomes were EAO colorectal neoplasia (CRN) and advanced colorectal neoplasia (aCRN) prevalence. Subgroup analyses were performed based on sex, geographic location, time period, and age, including comparison with those aged 50–59 years. Generalized linear mixed model with random intercept logistic regression and fixed subgroup effects were performed. Results: Of 10,123 unique articles, 17 studies published between 2002 and 2020, including 51,811 average-risk individuals from 4 continents, were included. The pooled rate of EAO-CRN was 13.7% (95% confidence interval [CI], 0.112%–0.168%) and EAO-aCRN was 2.2% (95% CI, 0.016%–0.031%). Prevalence of CRC was 0.05% (95% CI, 0.00029%–0.0008%). Rates of EAO-CRN were higher in men compared with women (relative risk, 1.71%; 95% CI, 1.49%–1.98%), and highest in the United States (15.6%; 95% CI, 12.2%–19.7%) compared with Europe (14.9%; 95% CI, 6.9%–29.3%), East Asia (13.4%; 95% CI, 10.3%–17.2%), and the Middle East (9.8%; 95% CI, 7.8%–12.2%) (P = .04) The rate of EAO-CRN in age groups 45–49 years and 50–59 years was 17.8% (95% CI, 14.5%–21.6%) and 24.8% (95% CI, 19.5%–30.8%), respectively (P = .04). The rate of EAO-aCRN in age group 45–49 years was 3.6% (95% CI, 1.9%–6.7%) and 4.2% (95% CI, 3.2%–5.7%), respectively (P = .69). Conclusions: The rate of aCRN in individuals aged 45–49 years was similar to the rate observed in individual aged 50–59 years, suggesting that expanding screening to this population could yield a similar impact on colorectal cancer risk reduction.