Previous studies have tested the effect of soy and breast cancer on animals, but this is the first time the study has been carried out in-vitro.
"In our study we used cell cultures to examine the effects of isoflavones on the invasion of breast cancer cells," said Dr Pamela Magee from the university's School of Biomedical Sciences. "The isoflavones exerted potent inhibitory effects on breast cancer cell invasion, even at concentrations similar to those found in South East-Asian populations."
South-East Asian populations traditionally consume high amounts of soy and have a low incidence of breast cancer. Soy contains naturally occurring hormone-like compounds called isoflavones that scientists believe can inhibit breast cancer development.
"Our findings seem to indicate that eating a soy rich products such as soy milk, soy drinks and desserts, could have an important role in preventing the spread of cancer cells in the body," said Magee. "Further studies in human volunteers are now needed to confirm whether soy isoflavones will protect against breast cancer spread in patients."
Breast cancer is the most common form of cancer affecting women in the western world, with 950 women in Northern Ireland alone suffering from the disease per year.
There have been recent advances in tumour detection and treatment, but the spread of cancer remains a significant cause of mortality.
"The invasion of cancerous cells from their site of origin into the neighbouring environment enables cancerous cells to travel and grow at new sites within the body," said Maggee. "Any agent, therefore, which can prevent the invasive process could become a powerful tool in the prevention of cancer spread."
This study was funded by the EU's "Quality of Life and Management of Living Resources" project. Ulster is working with 12 European partners on this project and is now investigating the genes of invasion in breast cancer.
Last year, researchers from the Harvard Medical School assessed the combined impact of soy products and different types of tea on a breast cancer model in mice and found that a mixture of soy phytochemicals and green tea could help slow the progression of breast cancer.
The mice were treated with genistein-rich soy isoflavones, soy phytochemical concentrate, black tea and green tea individually, and then with a soy phytochemical-black tea mixture and a soy-green tea combination.
Researchers assessed the growth of tumours and increase in cells as well as expressions of tumour oestrogen receptors.
Both the soy isoflavones and the soy phytochemical concentrate led to dose-dependent inhibition of tumour growth by slowing cancer cell proliferation, they reported in the 1 January issue of the International Journal of Cancer (vol 108, issue 1, pp 8-14).