Childhood Soy Intake and Breast Cancer Risk in Asian American Women

National Cancer Institute, Bethesda, MD, USA.
Cancer Epidemiology Biomarkers & Prevention (Impact Factor: 4.13). 05/2009; 18(4):1050-9. DOI: 10.1158/1055-9965.EPI-08-0405
Source: PubMed


Historically, breast cancer incidence has been substantially higher in the United States than in Asia. When Asian women migrate to the United States, their breast cancer risk increases over several generations and approaches that for U.S. Whites. Thus, modifiable factors, such as diet, may be responsible.
In this population-based case-control study of breast cancer among women of Chinese, Japanese, and Filipino descent, ages 20 to 55 years, and living in San Francisco-Oakland (California), Los Angeles (California) and Oahu (Hawaii), we interviewed 597 cases (70% of those eligible) and 966 controls (75%) about adolescent and adult diet and cultural practices. For subjects with mothers living in the United States (39% of participants), we interviewed mothers of 99 cases (43% of eligible) and 156 controls (40%) about the daughter's childhood exposures. Seventy-three percent of study participants were premenopausal at diagnosis.
Comparing highest with lowest tertiles, the multivariate relative risks (95% confidence interval) for childhood, adolescent, and adult soy intake were 0.40 (0.18-0.83; P(trend) = 0.03), 0.80 (0.59-1.08; P(trend) = 0.12), and 0.76 (0.56-1.02; P(trend) = 0.04), respectively. Inverse associations with childhood intake were noted in all three races, all three study sites, and women born in Asia and the United States. Adjustment for measures of westernization attenuated the associations with adolescent and adult soy intake but did not affect the inverse relationship with childhood soy intake.
Soy intake during childhood, adolescence, and adult life was associated with decreased breast cancer risk, with the strongest, most consistent effect for childhood intake. Soy may be a hormonally related, early-life exposure that influences breast cancer incidence.

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    • "Two case-control studies (Do 2007, Shannon 2005) along with six cohort studies (Hedelin 2008, Horn-Ross 2002, Keinan-Boker 2004, Touillaud 2006, Travis 2008, Ward 2008) found no association between the intake of soy products, isoflavones and breast cancer risk. On the contrary, the majority of the case-control studies demonstrated an inverse association between soy food/soy products, isoflavones and breast cancer risk (dos Santos Silva 2004, Hirose 2005, Iwasaki 2009, Iwasaki 2008, Kim 2008, Korde 2009, Linseisen 2004, Verheus 2007, Wu 2002, Zhang 2009a, Zhang 2009d, Zhu 2011). It is important to highlight that only two of these studies were conducted in Western populations (Linseisen 2004, Verheus 2007), where the mean intake of isoflavones is substantially lower than in Asian countries. "
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    ABSTRACT: Breast cancer occurs as a result between genes–diet interactions. Concerning diet, only alcohol is widely recognized for being most consistently associated with breast cancer risk. The purpose of this review is to report through a systematic way the current scientific evidence relating breast cancer and diet, through original-research studies published in English language during the last decade, assessing the consumption of specific foodstuffs/food-nutrients in relation to the disease. The available literature suggests that soy food intake seems to be inversely associated with the disease, while no association seems to be reported for dietary carbohydrates and dietary fiber intake. The consumption of dietary fat, is probably suggestive of an increase in breast cancer risk, while studies evaluating the role of fruit/vegetable, meat as well as dietary patterns and breast cancer risk, provide inconsistent results. Diet seems to be modestly associated with the disease, highlighting the need for more studies to be conducted.
    International Journal of Food Sciences and Nutrition 09/2014; 66(1). DOI:10.3109/09637486.2014.950207 · 1.21 Impact Factor
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    • "Another potential exposure is alcohol; in a review of dietary factors and breast cancer, alcohol was the only consistent factor associated with increased risk [97], perhaps mediated through the association of alcohol with increased breast density. Although the literature is somewhat inconsistent, soy intake may be beneficial, with some studies citing intake during childhood [98] or during adulthood [99]. Physical activity levels may also be protective, and a case-control study noted that physical activity at ages 14 to 20 years decreased risk of breast cancer [100]. "
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    ABSTRACT: Early life exposures during times of rapid growth and development are recognized increasingly to impact later life. Epidemiologic studies document an association between exposures at critical windows of susceptibility with outcomes as diverse as childhood and adult obesity, timing of menarche, and risk for hypertension or breast cancer. This article briefly reviews the concept of windows of susceptibility for providers who care for adolescent patients. The theoretical bases for windows of susceptibility is examined, evaluating the relationship between pubertal change and breast cancer as a paradigm, and reviewing the underlying mechanisms, such as epigenetic modification. The long-term sequela of responses to early exposures may impact other adult morbidities; addressing these exposures represents an important challenge for contemporary medicine.
    Journal of Adolescent Health 05/2013; 52(5 Suppl):S15-20. DOI:10.1016/j.jadohealth.2012.09.019 · 3.61 Impact Factor
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    • "95% CI, .57e1.04; p trend ¼ .08) [45]. Four other studies (Table 1)done of Asian-American women [46]; one of non-Asians, mostly white Canadian women [47]; and the other two of Chinese women [48] [49]dreported that increased soy intake during adolescence reduced risk for adult breast cancer. "
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    ABSTRACT: It is increasingly evident that diet during preadolescence and adolescence has important consequences for breast cancer during adulthood. However, only a few epidemiologic studies have been conducted on the relationship between diet during preadolescence and adolescence, and cancer during adulthood. This situation is partly because of methodological challenges such as the long latency period, the complexity of breast cancer, the lack of validated diet assessment tools, and the large number of subjects that must be followed, all of which increase costs. In addition, funding opportunities are few for such studies. Results from the small number of epidemiologic studies are inconsistent, but evidence is emerging that specific aspects of the diet during preadolescence and adolescence are important. For example, during preadolescence and adolescence, severe calorie restriction with poor food quality, high total fat intake, and alcohol intake tend to increase risk, whereas high soy intake decreases risk. Research on preadolescent and adolescent diet is a paradigm shift in breast cancer investigations. This research paradigm has the potential to produce transformative knowledge to inform breast cancer prevention strategies through dietary intervention during preadolescence and adolescence, rather than later in life, as is current practice, when it is perhaps less effective. Methodological challenges that have plagued the field might now be overcome by leveraging several existing large-scale cohort studies in the U.S. and around the world to investigate the role of diet during preadolescence and adolescence in risk for adult breast cancer.
    Journal of Adolescent Health 11/2012; 52(5). DOI:10.1016/j.jadohealth.2012.08.008 · 3.61 Impact Factor
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