Funded by World Cancer Research Fund and led by the University of Oxford, the findings, published recently in the journal ESMO Real World Data and Digital Oncology, found over half of people starting systemic cancer treatment such as chemotherapy in England had a history of obesity, even though only around one in four were living with obesity when treatment began.

Associate Professor in Eperimental Cancer Therapeutics at the University of Oxford, Professor Simon Lord, said: ‘This study provides clear rationale for considering both current and past BMI in clinical decision making and outcomes research. Not doing so risks missing an important part of the clinical picture.'

The study found that on average, including historical BMI raised obesity prevalence from 26.4% to 53.5% and that lifetime obesity prevalence exceeded 50% in every one of the 13 cancer types studied. For pancreatic cancer, obesity at the start of treatment was only 13.7%, but lifetime obesity prevalence was 55.8%, demonstrating that current weight doesn't provide a complete picture of someone's health. 

Obesity is a risk factor for 13 cancer types, and global projections suggest that over 2m cancer cases could be attributable to obesity by 2070.