Currently 1.97 billion people worldwide are overweight or obese, both of which increase the risk of at least 12 different types of cancer. Low physical activity also increases the risk of three different cancers. However, there is a growing evidence that excess weight may increase the risk of several other cancers including small intestine, cervix, bladder, brain (meningioma), thyroid, Hodgkin’s lymphoma, non-Hodgkin’s lymphoma, multiple myeloma and leukemia.
Evidence also suggests that physical activity may reduce the risk of more than 13 cancers. This might mean that the established cancer burden due to excess weight and low physical activity may be substantially underestimated. If confirmed, this would add considerably to the cancer burden related to weight and physical activity.
Aims and objectives
The aim of the current project is to investigate the association between different measures of weight (BMI, waist, and hip measures) as well as different measures of physical activity (total, leisure-time, vigorous, moderate, light, walking) and the risk of 26 cancers.
Our hypothesis is that excess weight increases the risk of 20 specific cancers and that being more physically active reduces the risk of 15 specific cancers. We also hypothesise that hormones (such as oestrogen and testosterone), blood glucose levels, and specific diseases that can lead to cancer (gallstones for gallbladder cancer, pancreatitis for pancreatic cancer) may explain part of the associations between weight, physical activity and cancer risk.
How it will be done
We will use data from previous research that recorded the height, waist, hip, and body composition measurements (weight, body fat percentage, fat mass) of half a million British adults between 2006–2010. The data also includes information on participants physical activity, diet, smoking, alcohol intake, socio-demographic characteristics, and their health and medical history.
Of the half a million participants, 100,000 had their level physical activity measure using accelerometers and this will allow for more reliable estimates of the association between physical activity and cancer risk. Blood samples have been taken from all participants and biomarker data including blood glucose levels, hormone levels and markers of inflammation are available from all participants.
We will use all of this to examine the association between excess weight, physical activity and risk of 26 cancers, as well as using modern statistical methods to try to disentangle the biological processes within our body that may explain any observed associations between excess weight, physical activity, and cancer.
By clarifying the underlying biological processes that link for excess weight, physical activity, and a range of cancers in a large sample size, this project may contribute towards more conclusive evidence regarding excess weight and physical activity for a large range of cancers. This will also contribute towards more complete estimates of the cancer burden related to excess weight and physical activity and can ultimately contribute towards additional cancers being prevented by controlling weight and being physically active.