A large-scale UK Biobank study has revealed that central obesity, measured by waist circumference and waist-to-hip ratio, may be a stronger predictor of colorectal cancer (CRC) risk than overall body mass index (BMI). The study analysed data from over 458,000 individuals and found that the proportion of CRC cases attributable to central obesity was significantly higher than previously estimated using BMI alone.
The findings highlight that excess abdominal fat is more strongly associated with CRC incidence than general obesity. Researchers found that the population attributable fraction (PAF)—the proportion of cases linked to a risk factor, was 17.3% for high waist circumference and 17.6% for high waist-to-hip ratio. In contrast, BMI-based estimates suggested only 9.9% of CRC cases were attributable to obesity, a figure that rose to 15.7% after adjusting for prediagnostic weight loss.
The study followed participants for nearly 12 years and identified 5,944 CRC cases. The hazard ratio (HR) for CRC was significantly higher in individuals with high central obesity: those in the highest quartile of waist-to-hip ratio had a 40% higher risk of CRC compared to those in the lowest quartile. In comparison, the increased risk for individuals with a high BMI was 23%.
These findings suggest that traditional BMI measurements may underestimate the true impact of obesity on CRC risk. The authors emphasise the need to consider waist measurements as key indicators in cancer prevention strategies. Given the growing obesity epidemic, targeting abdominal fat reduction through dietary changes, physical activity, and public health interventions could play a crucial role in reducing colorectal cancer incidence.
Aleksandra Zurowska, EMJ
Reference
Safizadeh F et al. Colorectal Cancer and Central Obesity. JAMA Netw Open. 2025;8(1):e2454753.
