MedWire News: Women who are overweight and/or who show signs of insulin resistance are more likely to have advanced breast cancer at diagnosis than women without these Type 2 diabetes risk factors, study results suggest.

Insulin resistance is commonly caused by being overweight and inactive and is often a precursor to Type 2 diabetes.

The findings are particularly worrying considering the dramatic increase in obesity and Type 2 diabetes rates in recent years, said lead researcher Dr Anne Cust from the University of Melbourne in Australia.

Dr Cust and team studied data on more than 60,000 Swedish women who did not have breast cancer at the start of the monitoring period in 1985.

All the participants underwent blood tests to measure their glucose and insulin levels, and their body mass index was also calculated.

By 2005, more than 700 of the women had developed breast cancer.

Analysis revealed that women with a high body mass index and/or those with signs of insulin resistance were around 50% more likely to be diagnosed with advanced breast cancer than those without these characteristics.

The findings remained true after accounting for factors such as age and physical activity levels.

"Women with insulin resistance or who were overweight were less likely to be diagnosed with stage I breast cancers but at greater risk of being diagnosed with stage II to IV tumours - larger more advanced cancers,'' said Dr Cust.

Speaking at the Population Health Congress in Brisbane, Australia, she concluded: "We know that being overweight and having insulin resistance is a risk factor for getting cancer but - in the case of breast cancer - our study indicates that the cancer will be more advanced."