Women with type 2 diabetes are nearly 30% more likely to get breast cancer, according to a comprehensive review of 40 separate studies examining the potential link between breast cancer and diabetes. The analysis, by researchers at the International Prevention Research Institute (i-PRI), Lyon, is published in the British Journal of Cancer.
The studies involved over 56,000 cases of breast cancer across 4 continents. Researchers discovered that postmenopausal women with type 2 diabetes had a 27% increased risk of breast cancer. No association was found among women of premenopausal age or those women with type 1 diabetes.
A high body mass index (BMI), which is often associated with diabetes, may be an underlying contributing factor, according to study authors. Obesity increases the risk of postmenopausal breast cancer by up to 30%.
“We don’t yet know the mechanisms behind why type II diabetes might increase the risk of breast cancer. On the one hand, it’s thought that being overweight, often associated with type 2 diabetes, and the effect this has on hormone activity may be partly responsible for the processes that lead to cancer growth. But it’s also impossible to rule out that some factors related to diabetes may be involved in the process,” said Professor Peter Boyle, President of i-PRI and lead author of the study.
Source: Cancer Research UK.