From ANIMAL PEOPLE, September 2002:

LONDON, NEW YORK–Frequent consumption of soya milk and
tofu, the curded form of tofu favored in cooking, may reduce the
risk of breast cancer, the British charity Cancer Research U.K.
announced on July 6, 2002, citing findings from a study of 406
women living in Singapore.
Working in partnership with the U.S. National Cancer
Institute and the National University of Singapore, Cancer Research
U.K. scientists found that the women who ate the most tofu were 60%
less likely to develop the forms of high-density breast tissue most
associated with developing breast cancer. The findings were reported
the the peer-reviewed journal Cancer Epidemiology, Biomarkers and
Prevention.
Often used in place of cow’s milk and meat products, soya
milk and tofu are staples of vegan and vegetarian diets in the U.S.
and Britain.
The study was the second in recent months to link
vegetarianism with reduced risk of breast cancer.
The International Journal of Cancer in May 2002 published a
study of 717 South Asian women who had emigrated to Britain, 240 of
whom subsequently developed breast cancer while 477 did not.
Isabel dos Santos Silva, M.D., and colleagues at the London
School of Hygiene and Tropical Medicine found that “lifelong
vegetarianism may be associated with a reduction in the risk of
breast cancer through its association with a higher intake of
vegetables and (legumes).”