Tofu and risk of breast cancer in Asian-Americans.

Breast cancer rates among Asian-Americans are lower than those of US whites but considerably higher than rates prevailing in Asia. It is suspected that migration to the US brings about a change in endocrine function among Asian women, although reasons for this change remain obscure. 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 frequency of intake of some 90 food items, 597 Asian-American women (70% of those eligible) diagnosed with incident, primary breast cancer during 1983-1987 and 966 population-based controls (75% of those eligible) were interviewed. Controls were matched to cases on age, ethnicity, and area of residence. This analysis compares usual adult intake of soy (estimated primarily from tofu intake) among breast cancer cases and control women. After adjustment for age, ethnicity and study area, intake of 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 per year). Among migrants, intake of tofu decreased with years of residence in the US. Risk of breast cancer decreased with increasing frequency 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. This association remained after adjustment for selected dietary factors and menstrual and reproductive factors. However, this study was not designed specifically to investigate the role of soy intake and our assessment of soy intake may be incomplete. We cannot discount the possibility that soy intake is a marker of other protective aspects of Asian diet and/or Asian lifestyle.

[1]  A M Nomura,et al.  Migration patterns and breast cancer risk in Asian-American women. , 1993, Journal of the National Cancer Institute.

[2]  R. Hoover,et al.  Relative weight, weight change, height, and breast cancer risk in Asian-American women. , 1996, Journal of the National Cancer Institute.

[3]  D. Mishell,et al.  Single luteal phase serum progesterone assay as an indicator of ovulation. , 1997, American journal of obstetrics and gynecology.

[4]  Rosenberg Dp.  Dietary fiber, phytoestrogens, and breast cancer. , 1992 .

[5]  H. Adlercreutz,et al.  Urinary excretion of lignans and isoflavonoid phytoestrogens in Japanese men and women consuming a traditional Japanese diet. , 1991, The American journal of clinical nutrition.

[6]  K. Setchell,et al.  Biological effects of a diet of soy protein rich in isoflavones on the menstrual cycle of premenopausal women. , 1994, The American journal of clinical nutrition.

[7]  H. Adlercreutz,et al.  Genistein is an effective stimulator of sex hormone-binding globulin production in hepatocarcinoma human liver cancer cells and suppresses proliferation of these cells in culture , 1993, Steroids.

[8]  N. Breslow,et al.  The analysis of case-control studies , 1980 .

[9]  N. Day,et al.  Dietary effects on breast-cancer risk in Singapore , 1991, The Lancet.

[10]  C. Weinberg,et al.  Dietary intervention study to assess estrogenicity of dietary soy among postmenopausal women. , 1995, The Journal of clinical endocrinology and metabolism.

[11]  K. Anderson,et al.  Effects of soya consumption for one month on steroid hormones in premenopausal women: implications for breast cancer risk reduction. , 1996, Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology.

[12]  B. Henderson,et al.  Diet and breast cancer in Shanghai and Tianjin, China. , 1995, British Journal of Cancer.

[13]  N. Breslow,et al.  Statistical methods in cancer research: volume 1- The analysis of case-control studies , 1980 .

[14]  H. Adlercreutz.  Western diet and Western diseases: some hormonal and biochemical mechanisms and associations. , 1990, Scandinavian journal of clinical and laboratory investigation. Supplementum.

[15]  M. Pike,et al.  Sex hormones in women in rural China and in Britain. , 1990, British Journal of Cancer.

[16]  B. Macmahon,et al.  Urine œstrogen profiles OF Asian and North American women , 1974 .

[17]  M. Pike,et al.  Dietary soy protein and hormonal status in females. , 1995, The American journal of clinical nutrition.

[18]  S. Barnes.  Effect of genistein on in vitro and in vivo models of cancer. , 1995, The Journal of nutrition.

[19]  S. Barnes,et al.  Soy intake and cancer risk: a review of the in vitro and in vivo data. , 1994, Nutrition and cancer.

[20]  D. Rose.  Dietary fiber, phytoestrogens, and breast cancer. , 1992, Nutrition.

[21]  H. Adlercreutz,et al.  Effect of dietary components, including lignans and phytoestrogens, on enterohepatic circulation and liver metabolism of estrogens and on sex hormone binding globulin (SHBG). , 1987, Journal of steroid biochemistry.

[22]  G. Peterson.  Evaluation of the biochemical targets of genistein in tumor cells. , 1995, The Journal of nutrition.

[23]  B. Modan,et al.  Dietary factors and risk of breast cancer: combined analysis of 12 case-control studies. , 1990, Journal of the National Cancer Institute.

[24]  H. Adlercreutz,et al.  Dietary phytoestrogens and cancer: in vitro and in vivo studies , 1992, The Journal of Steroid Biochemistry and Molecular Biology.

[25]  M. Pike,et al.  Menstrual and reproductive factors and risk of breast cancer in Asian-Americans. , 1996, British Journal of Cancer.

[26]  S. Barnes,et al.  The role of soy products in reducing risk of cancer. , 1991, Journal of the National Cancer Institute.

[27]  M. Juliana,et al.  Effect of miso (Japanese soybean paste) and NaCl on DMBA-induced rat mammary tumors. , 1990, Nutrition and cancer.

[28]  J. Dwyer,et al.  The relationship between estrogen levels and diets of Caucasian American and Oriental immigrant women. , 1986, The American journal of clinical nutrition.

[29]  S. Barnes,et al.  Soybeans inhibit mammary tumors in models of breast cancer. , 1990, Progress in clinical and biological research.

[30]  Victoria Persky,et al.  Epidemiology of soy and cancer: perspectives and directions. , 1995, The Journal of nutrition.

[31]  H. Adlercreutz,et al.  14 – Mammalian Lignans and Phyto-oestrogens Recent Studies on their Formation, Metabolism and Biological Role in Health and Disease , 1988 .

[32]  N. E. Breslow.  Statistical Methods in Cancer Research , 1986 .

[33]  B. Macmahon,et al.  Oestrogen profiles of Asian and North American women. , 1971, Lancet.