TOFU AND RISK OF BREAST-CANCER IN ASIAN-AMERICANS

Breast cancer rates among Asian-Americans are lower than those of US w hites but considerably higher than rates prevailing in Asia, It is sus pected that migration to the US brings about a change in endocrine fun ction among Asian women, although reasons for this change remain obscu re, The high intake of soy in Asia and its reduced intake among Asian- Americans has been suggested to partly explain the increase of breast cancer rates in Asian-Americans. We conducted a population-based case- control study of breast cancer among Chinese-, Japanese-, and Filipino -American women in Los Angeles County MSA, San Francisco Oakland MSA, and Oahu, Hawaii, Using a common questionnaire which assessed frequenc y of intake of some 90 food items, 597 Asian-American women (70% of th ose eligible) diagnosed with incident, primary breast cancer during 19 83-1987 and 966 population-based controls (75% of those eligible) were interviewed, Controls were matched to cases on age, ethnicity, and ar ea of residence, This analysis compares usual adult intake of soy (est imated primarily from tofu intake) among breast cancer cases and contr ol women, After adjustment for age, ethnicity and study area, intake o f tofu was more than twice as high among Asian-American women born in Asia (62 times per year) compared to those born in the US (30 times pe r year), Among migrants, intake of tofu decreased with years of reside nce in the US, Risk of breast cancer decreased with increasing frequen cy of intake of tofu after adjustment for age, study area, ethnicity, and migration history; the adjusted OR associated with each additional serving per week was 0.85 (95% CI = 0.74-0.99), The protective effect of high tofu intake was observed in pre- and postmenopausal women. Th is association remained after adjustment for selected dietary factors and menstrual and reproductive factors. However, this study was not de signed specifically to investigate the role of soy intake and our asse ssment of soy intake may be incomplete, We cannot discount the possibi lity that soy intake is a marker of other protective aspects of Asian diet and/or Asian lifestyle.