{
  "abstract": "Introduction Surveillance for nonadvanced adenomas (NAAs) relies on lesion count, but evidence is limited for individuals with 3–4 or 5–10 NAAs and for size-based risk stratification. We evaluated advanced colorectal neoplasm (ACN; adenomas ≥10 mm, tubulovillous/villous histology, high-grade dysplasia, or cancer) risk by NAA count and size.Methods A total of 16,870 adults aged 50–75 with ≥2 colonoscopies (2004–2023) were classified into 4 groups by NAA count and by size (diminutive ≤5 mm vs. small 6–9 mm). Over a median 5.3-year follow-up, ACN risk was assessed using multivariable Cox regression and inverse probability of censoring weighting (IPCW) models.Results Participants were categorized by NAA count: 0 (n=10,023), 1–2 (n=5,869), 3–4 (n=781), and 5–10 (n=197). Five-year cumulative incidences of ACN were 1.3% (95% CI, 1.0–1.5), 4.0% (3.4–4.7), 5.3% (3.6–7.8), and 10.1% (5.8–17.1). In IPCW analysis, adjusted HRs (95% CI) compared with no adenoma group were 1.64 (1.36–1.97), 2.75 (1.91–3.97), and 5.21 (2.89–9.38). Risk was higher in 3–4 NAAs than in 1–2 NAAs (HR, 1.68; 95% CI, 1.16–2.43). The presence of small adenomas (vs. diminutive-only) increased ACN risk in 1–2 NAAs (HR, 1.38; 1.09–1.76) and 3–4 NAAs (HR, 2.39; 1.70–3.36).Conclusions ACN risk increased with NAA count, with the highest risk observed in 5–10 NAAs, while 3–4 NAAs had higher risk than 1–2 NAAs. Small adenomas further elevated risk within count-based groups. Both NAA number and size should be considered when determining surveillance intervals.",
  "authors": [
    {
      "affiliations": [
        "Department of Internal Medicine and Healthcare Research Institute, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, South Korea"
      ],
      "name": "Jiyeon Seo"
    },
    {
      "affiliations": [
        "Department of Internal Medicine and Healthcare Research Institute, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, South Korea"
      ],
      "name": "Jung Kim"
    },
    {
      "affiliations": [
        "Healthcare Research Institute, Healthcare System Gangnam Center, Seoul National University Hospital,, Seoul, South Korea"
      ],
      "name": "Huiyeon Kim"
    },
    {
      "affiliations": [
        "Department of Internal Medicine and Healthcare Research Institute, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, South Korea"
      ],
      "name": "Jung Ho Bae"
    }
  ],
  "title": "P323 Nonadvanced adenoma number and size as predictors of metachronous advanced colorectal neoplasm: implications for surveillance guidelines",
  "uid": "eee6c319-619a-5d71-84ca-2ad2954bfcb2"
}