The cholesterol-busting drugs do not prevent the disease but help to contain it, a US study found.
It raises hopes statins could be used with current therapies to improve life expectancy.
Prof Alan Wells, of Pittsburgh University, said the dosage needed was similar to levels used safely by heart patients.
Statins could also prevent tumours spreading from other organs such as the prostate, the most common cancer in men.
He said: "These effects are significant for several reasons. First, the doses of atorvastatin used are similar to those used for moderate-intensity lipid lowering therapy in clinical patients."
Once breast cancer has spread the disease becomes more aggressive and generally resistant to chemotherapy.
Prof Wells said: "We demonstrate that statins can directly affect the proliferation of breast cancer cells, specifically at the metastatic site.
"As statins can block metastatic tumour growth they should be considered for use as long-term added drugs to delay clinical emergence and decrease mortality in breast cancer patients."
Scientists have known for some time oestrogen helps cancer to spread, which is why women are usually given anti-hormone treatments following chemotherapy and surgery.
Over 55,000 women are diagnosed with breast cancer each year in the UK. It claims around 11,400 lives annually.
Dr Kotryna Temcinaite, Research Communications Manager at Breast Cancer Now, said: "This interesting early research adds to the growing body of evidence that statins could be a really valuable addition to breast cancer treatment.
"But clinical trials will be needed to understand whether statins could suppress the growth of breast cancer cells that have spread around the body in humans."
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