WOMEN who are overweight or show early signs of type 2 diabetes are at far greater risk of advanced breast cancer, a study led by Melbourne researchers has revealed.

A trial involving more than 60,000 women found that those who were overweight, insulin-resistant or had high blood-sugar levels were 50% more likely to be diagnosed with advanced forms of the disease.

It is one of the first studies of its kind to link precursors for type 2 diabetes to the stage of cancer diagnosis.

The collaboration between doctors from the University of Melbourne, Umea University in Sweden and the German Cancer Research Centre tracked Swedish women between 1985 and 2005. They were cancer-free when recruited and had their blood tested for glucose and insulin levels and other hormones associated with obesity and diabetes risk.

About 600 women were later diagnosed with breast cancer. Those who showed early signs of diabetes were more likely to develop the disease than those who showed no risk factors.
 

The University of Melbourne's Anne Cust will present the findings, which are published in the journal Breast Cancer Research and Treatment, at a population health conference in Brisbane today.

Dr Cust said women who were insulin-resistant or overweight were less likely to be diagnosed with stage one breast cancers but at greater risk of being diagnosed with stage two to four tumours, which are larger.

"More advanced cancers are associated with a worse prognosis, so the earlier you pick up breast cancer the better," she said. "It's just adding further evidence that women should try to maintain a healthy weight and remain active."

The director of epidemiology at the Cancer Council Victoria, Graham Giles, said the findings were significant.

"In a way, it's a good thing that these risk factors are converging for all these diseases our society is afflicted with … because the answer is the same: do whatever you can to avoid being overweight or obese by having a healthy diet and being more physically active," he said.