Dietary Patterns and Risk of Early- and Late-Onset Colorectal Cancer Among Korean Adults: A Hospital-Based Case-Control Study

Objective Early-onset colorectal cancer (EOCRC) is increasing globally, but evidence regarding dietary patterns in relation to EOCRC and late-onset colorectal cancer (LOCRC) remains limited. We aimed to compare the associations between dietary patterns and the risk of EOCRC and LOCRC.Methods A hospital-based case-control study with 1:2 individual matching on sex and age (±5 years) was conducted. The analysis included 1,401 colorectal cancer cases (280 EOCRC and 1,121 LOCRC) and 2,800 controls (560 matched to EOCRC cases and 2,240 matched to LOCRC cases). Dietary patterns were identified using principal component analysis of 35 food groups derived from a food frequency questionnaire.Results In EOCRC, the Prudent dietary pattern was inversely associated with EOCRC (ORT3 vs. T1 = 0.261; 95% CI, 0.141–0.482). In LOCRC, the Traditional Korean dietary pattern was positively associated with LOCRC (ORT3 vs. T1 = 1.635; 95% CI, 1.257–2.128), whereas the Prudent dietary pattern was inversely associated with LOCRC (ORT3 vs. T1 = 0.342; 95% CI, 0.252–0.465). In an exploratory case-case analysis, LOCRC cases had higher Traditional Korean dietary pattern scores, whereas EOCRC cases had higher Western dietary pattern scores.Conclusion These findings suggest that the Prudent dietary pattern was inversely associated with both EOCRC and LOCRC, while differences in other dietary patterns between the two groups warrant further investigation in prospective cohort studies. However, limitations related to the timing of dietary assessment and potential reverse causation should be considered when interpreting these findings.