Obesity as a risk factor for early-onset colorectal cancer: Evidence from a nationally representative database

BACKGROUND: Colorectal cancer (CRC) is the second leading cause of cancer-related deaths worldwide with an alarming rise in early-onset CRC (eoCRC) over the past several decades. Unlike late-onset CRC, the drivers behind eoCRC remain less clear. While certain risk factors such as obesity and smoking have demonstrated a relatively strong association with eoCRC in the literature, some studies have challenged these associations, emphasizing the need for additional studies. AIM: To investigate the impact of various risk factors on eoCRC with a special focus on obesity. METHODS: < 0.05 defined as significant. Unadjusted models demonstrated significant associations of eoCRC with BRI quartiles, as well as BMI-defined obesity, WC, and smoking. In unadjusted models, BRI remained the strongest independent predictor; those in the highest BRI quartiles had over 10-fold greater odds of eoCRC. In fully adjusted models, BRI remained significant, but BMI- and waist-based obesity were not. CONCLUSION: BRI is a stronger predictor of eoCRC risk compared to other obesity indices and is a superior tool for identifying young individuals at higher risk of CRC.