Belly Fat vs BMI in Colorectal Cancer Risk

A recent study highlights that central obesity, specifically belly fat, is a stronger predictor of colorectal cancer (CRC) risk than general body mass index (BMI). This research, conducted on 460,784 participants from the UK Biobank, challenges the reliance on BMI alone for assessing obesity-related cancer risk and emphasizes the importance of waist-to-hip ratio (WHR) and waist circumference (WC) in determining colorectal cancer risk.

The study found that an increase in WHR was associated with a higher risk of CRC, with a hazard ratio (HR) of 1.18 per standard deviation increase, compared to 1.10 for BMI. Even after adjusting for BMI, the link between WHR and CRC risk remained significant. In contrast, after adjusting for WHR, the association between BMI and CRC risk weakened considerably. This suggests that belly fat, as indicated by WHR, plays a much more significant role in CRC risk than overall body weight as measured by BMI.

Importantly, WHR was strongly correlated with both colon and rectal cancer risks in both men and women, while BMI showed little to no significant correlation, especially in women and for rectal cancer. This finding suggests that relying on BMI alone may not provide an accurate risk assessment for colorectal cancer, especially when it comes to central obesity.

The results advocate for the inclusion of WHR and WC as key tools in assessing obesity and CRC risk, alongside BMI. Incorporating these measurements could improve early detection and prevention strategies for colorectal cancer, a leading cause of cancer-related deaths globally. As the prevalence of obesity continues to rise, understanding the role of central obesity in CRC risk becomes increasingly crucial in public health.

This study, led by Fatemeh Safizadeh from the German Cancer Research Center, also highlights the limitations of using single baseline measurements for obesity and emphasizes the need for more comprehensive research on how changes in obesity patterns over time influence cancer risk. For healthcare professionals, this research supports a more nuanced approach to assessing obesity, which could lead to more effective prevention and management strategies for colorectal cancer and other obesity-related diseases.

More Information: Safizadeh, F., Mandic, M., Schöttker, B. et al. Central obesity may account for most of the colorectal cancer risk linked to obesity: evidence from the UK Biobank prospective cohort. Int J Obes (2024). https://doi.org/10.1038/s41366-024-01680-7