The distribution of body fat may play an important role in predicting a person's risk of certain malignancies, according to new international research headed by the University of Bristol and published in the Journal of the National Cancer Institute recently. 

Obesity has long been associated with an increased risk of cancer, but doctors often assess it using body mass index (BMI). However, BMI simply evaluates weight in proportion to height and does not indicate where fat is stored in the body. Growing data from heart health research suggests that this constraint is significant, and the latest findings apply that knowledge to cancer. 

Researchers from Bristol's Integrative Cancer Epidemiology Programme (ICEP) studied whether fat in specific body locations affects the risk of 12 obesity-related malignancies, including breast, colorectal, ovarian, pancreatic, and liver cancer. They investigated health outcomes across huge datasets using Mendelian randomisation, a statistical approach based on genetic variation. 

Their findings demonstrate that fat distribution is important, although the effect varies according to the type of cancer. For some malignancies, where fat is accumulated is more important than how much is stored overall. Others place a greater emphasis on overall fat content. In others, both number and location are significant. 

"This indicates that there is no universal approach to cancer risk and obesity," stated main author Dr Emma Hazelwood, who recently completed her PhD at the University of Bristol. "BMI can capture population-level trends, but it may be too simplistic to assess individual risk." 

The study supports growing demands to move beyond BMI as the primary diagnostic tool for obesity-related health hazards. Recent frameworks from the European Association for the Study of Obesity and the Lancet Commission on the Future of Obesity indicate that body composition and fat distribution are more important. 

Understanding these pathways could assist in identifying high-risk individuals and drive more personalised preventative methods, such as lifestyle changes or medical therapy. 

Dr Julia Panina, Head of Research Funding at the World Cancer Research Fund, which co-funded the study, stated that "maintaining a healthy weight remains essential." However, data now suggests that how fat is distributed in the body is just as important. 

The researchers emphasise that further research is needed, particularly in non-European groups, to completely understand how different types of body fat affect cancer biology. 

"Exploring how obesity treatments—whether lifestyle or drug-based—affect these pathways is a vital next step," says Dr Hazelwood.