Dr Pamela Magee, from the School of Biomedical Sciences, has been investigating the effects of a group of dietary compounds, found almost exclusively in soy foods, in the prevention of cancer spread.

Dr Magee said: "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.

"But among South-East Asian populations, and in areas where soy products are traditionally consumed in high amounts in the diet, incidence of breast cancer is low.

"Soy contains naturally occurring hormone-like compounds called isoflavones that scientists believe can inhibit breast cancer development.

"In our study we used cell cultures to examine the effects of isoflavones on the invasion of breast cancer cells. The isoflavones exerted potent inhibitory effects on breast cancer cell invasion, even at concentrations similar to those found in South East-Asian populations.

"These novel 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. Further studies in human volunteers are now needed to confirm whether soy isoflavones will protect against breast cancer spread in patients.

"Although recent advances have been made in tumour detection and treatment, 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. Any agent, therefore, which can prevent the invasive process could become a powerful tool in the prevention of cancer spread."

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Carmen L. Lewis, M.D., M.P.H., from The University of North Carolina at Chapel Hill, and colleagues surveyed 605 women aged 40 to 69 years in ten general internal medicine practices in North Carolina in 2000. The survey was designed to determine each woman's breast cancer risk and then to assess eligibility for chemoprevention (using tamoxifen to prevent breast cancer). The researchers determined the women's five-year breast cancer risk based on age, ethnicity, number of first-degree relatives with breast cancer, age at first menstruation, age at first live birth, number of breast biopsies, and presence of atypical hyperplasia (abnormal cells that may be indicative of cancer) in a biopsy specimen. Women with an estimated five-year breast cancer risk of at least 1.66 percent were defined as having an increased breast cancer risk. To determine the possible risks of taking tamoxifen, the women were questioned about their medical history; specifically, whether their physicians had told them they had high blood pressure, diabetes mellitus, blood clots in the legs, or blood clots in the lungs.

The researchers found that among white women, nine percent in their 40s, 24 percent in their 50s, and 53.4 percent in their 60s had a five-year estimated breast cancer risk of 1.66 percent or greater. Among black women, 2.9 percent in their 40s, 7.1 percent in their 50s, and 13 percent in their 60s had a similar risk. When the possible side effects of tamoxifen were considered in white women, ten percent or fewer in all age groups were judged to be potentially appropriate for chemoprevention using tamoxifen. In women identified as at an increased risk for breast cancer, the maximum proportion of breast cancers that would be prevented was 6 to 8.3 percent, according to the researchers' calculations.

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