Washington, Apr 10 : A potent chemical found in soy may curtail breast cancer development, only if eaten during puberty, says a researcher.
Leena Hilakivi-Clarke, Ph.D., a professor of oncology at the Lombardi Comprehensive Cancer Centre at Georgetown said that results from animal and human studies have shown that genistein, a potent chemical found in soy can shield against breast cancer only if consumed during puberty.
However, she also said scientists need to conduct further studies why soy appears to protect against breast cancer in women.
"Timing seems to be vitally important in use of this bioactive food, and if we can figure out why that is so, then we may be able to help prevent breast cancer in the widest sense possible," said Hilakivi-Clarke.
Three studies conducted over human examined soy use during puberty and breast cancer development in later life. Out of three, two studies focussed on Asian females, who eat soy in their traditional diet.
The studies revealed that soy offered a very strong protective effect with more than 50 percent reduction in breast cancer risk, when soy is eaten during childhood and adolescence.
Other studies conducted over mice and rats provided strongest evidence for genistein's protective effect. It showed that prepubertal exposure to genistein had a consistent reduction in mammary cancer risk.
Further studies revealed that use of genistein in puberty cut the number of so-called "terminal end buds" in the breast. These are the structures that lead to growth of the mammary epithelium, which are the cells lining milk ducts, etc., and it is in these epithelial cells that breast cancer originates.
But Hilakivi-Clarke said that it is not clear if a mere reduction in the number of these structures could reduce cancer risk, or why.
The report appears online in British Journal of Cancer.