Lowering cholesterol with statin drugs could help prevent breast cancer, new research suggests.
A study of more than 600,000 British women found that breast cancer risk was almost doubled in those with abnormally high levels of blood fats.
The research is still at an early stage and the findings do not prove that cholesterol helps trigger breast cancer.
But if future work demonstrates a causal link it opens up the possibility of using cheap cholesterol-lowering statins to reduce women's risk of the disease.
"We found that women with high cholesterol had a significantly greater chance of developing breast cancer," University of Aston cardiologist Rahul Potluri said.
"This was an observational study so we can't conclude that high cholesterol causes breast cancer, but the strength of this association warrants further investigation.
"A prospective study that monitors the risk of breast cancer in women with and without high cholesterol is needed to confirm what we observed. If the connection between high cholesterol and breast cancer is validated, the next step would be to see if lowering cholesterol with statins can reduce the risk of developing cancer."
A total of 664,159 women from across the UK whose health records were stored on a large database took part in the study.
Almost 23,000 (3.4 per cent) had hyperlipidaemia, meaning their blood contained abnormally high levels of lipid fats - essentially cholesterol and triglycerides.
Some 530 women with the condition were among the 9,312 who developed breast cancer.
Statistical analysis showed they were 1.64 times more likely to have the disease than women without hyperlipidaemia.
Previous research has shown a clear association between obesity and breast cancer in post-menopausal women.
A US study last year found that a cholesterol product called 27HC fuelled human breast tumours in genetically engineered laboratory mice.
Scientists also discovered higher levels of 27HC in both healthy breast tissue and tumour cells in women with breast cancer.