Background:
Despite the worrisome rise in early onset colorectal cancer (EOCRC), our understanding remains superficial. Most studies describing the characteristics of persons with EOCRC have been conducted in large cancer datasets, which have limited diversity and granularity, and do not comment on precancerous lesions. Colorectal adenomas (CRAs) are the precursor lesion to EOCRC and can be resected to prevent cancer. Identifying which persons are most likely to have CRAs can lead to targeted screening strategies. We identify the prevalence of CRAs and associated risk factors in average-risk individuals <50 undergoing colonoscopy for benign indications at our diverse ambulatory center.
Methods:
We conducted a retrospective cohort study of average-risk persons ages 18-49 who underwent a colonoscopy at the University of Miami’s ambulatory care hub between 2020-2023. To capture an average-risk population, subjects identified as high-risk CRC (i.e., personal history CRAs or polyps, family history of CRC, inflammatory bowel disease, genetic syndromes, or “high-risk” indications) were excluded. Using endoscopic and pathologic reports, we utilized keyword search to identify whether persons had any CRA, defined as at least one tubular, villous, or tubulovillous adenoma. Categorical and continuous patient characteristics were compared across these groups via Fishers exact test and t-test, respectively. A multivariable logistic regression model was built by backwards stepwise selection to adjust for cofounding factors.
Results:
We identified 1417 persons of which 275 (19%) had at least one CRA (Table 1). Persons with CRAs were more likely to be older (mean: 45.45 vs 39.96), male (49.1% vs 38.6%), Hispanic (66.9% vs 58.2%), and have a higher BMI (mean: 29.14 vs 27.08 kg/m2); but, less likely to be US-born (26.2% vs 44.8%). In the multivariable logistic regression, increasing age and BMI and male sex were associated with increased risk of CRA (Table 2). Being US-born (OR 0.51, 95% CI: 0.37-0.69), and using aspirin (OR 0.31, 95% CI: 0.12-0.71) were associated with decreased risk of having a CRA.
Conclusions:
In this study of average-risk individuals <50 undergoing colonoscopy at our diverse ambulatory center, we identify that 19% had CRAs. Our findings are consistent with prior studies linking higher BMI, increasing age, and male sex to EOCRCs. However, we found strikingly protective associations in those who are US-born and use aspirin. Larger studies should investigate whether there are increased rates of EOCRC and CRAs in immigrants residing in the US, and continue to granularly define at-risk populations to target screening.

<b>Table 1.</b> Participant demographics (N = 1417).

Table 1. Participant demographics (N = 1417).

<b>Table 2.</b> Results of multivariable logistic regression model.

Table 2. Results of multivariable logistic regression model.

Catherine Blandon

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