Prevalence of Colorectal Neoplasia in Average-risk Vietnamese Adults Under 50 Years Undergoing Screening Colonoscopy

Colorectal cancer (CRC) screening is recommended for average-risk individuals beginning at age 45, as CRC incidence has been increasing rapidly among those aged below 50 years, particularly in Asia. However, data on the prevalence and characteristics of colorectal neoplasia in average-risk adults under 50 years remain limited.

We retrospectively analyzed data from 2094 average-risk adults aged below 50 years who underwent screening colonoscopy at a tertiary hospital between January and December 2024. Demographics, polyp characteristics, and histopathological results were recorded. Logistic regression was performed to identify age-related trends, adjusting for sex and body mass index.

The prevalence of adenomas, advanced adenomas (AAs), and clinically significant serrated polyps (CSSPs) was 24.8%, 3.9%, and 6.5%, respectively. Adenoma and AA rates increased significantly after age 40, whereas the prevalence of CSSPs remained stable across age groups. Compared with individuals aged below 40 years, the adjusted odds ratios (ORs) for adenomas were 2.09 (95% CI: 1.62-2.70) and 2.78 (95% CI: 2.18-3.55) for ages 40 to 44 and 45 to 49, respectively. For AAs, the corresponding ORs were 1.91 (95% CI: 1.08-3.38) and 2.52 (95% CI: 1.48-4.29).

Colorectal neoplasia was common from age 40 onward, with comparable prevalence between those aged 40 to 44 and 45 to 49 years. These findings provide clinically relevant evidence for optimizing the age threshold to begin CRC screening in Asian populations.