Prevalence, sources, and predictors of soy consumption in breast cancer (original) (raw)

Point-Counterpoint: Soy Intake for Breast Cancer Patients

Integrative Cancer Therapies, 2002

Should breast cancer patients consume soy, either as soy foods or soy supplements? Postmenopausal patients, as well as patients experiencing early menopause induced by adjuvant chemotherapy, may be inclined to use soy products as a &dquo;natural&dquo; alternative to hormone replacement therapy (HRT). Others may be motivated to consume soy products based on the belief that they may improve their prognosis or prevent a recurrence. Such beliefs lack the support of clinical data, as relatively few studies of soy have yielded information relevant to individuals diagnosed with breast cancer. Moreover, concern has arisen over a potential adverse impact of soy intake by breast cancer patients because of the estrogen-like effects of the isoflavones, notably genistein and daidzein, contained in soy. Estrogens have been linked to breast cancer promotion and progression, and some preclinical studies suggest that soy or its isoflavones may indeed increase proliferation of breast cancer cells. Other laboratory research indicates, however, that genistein and daidzein exert a wide range of anticancer activities as well.

Factors to consider in the association between soy isoflavone intake and breast cancer risk

Journal of Epidemiology, 2010

It has been suggested that soy isoflavones have protective effects against breast cancer. However, data from epidemiological studies are not conclusive. A recent meta-analysis showed that soy intake was inversely associated with breast cancer risk in Asian but not Western populations, which indicates that protection against breast cancer may require that women consume levels of soy typical in Asian diets. In addition to the amount of soy isoflavones consumed, the form and food source of isoflavones, timing of isoflavone exposure, estrogen receptor status of tumors, and equol-producer status and hormonal profile of individuals may modify the association between soy isoflavone intake and the risk of breast cancer. These factors might explain the heterogeneity of results from studies. This present report contrasts background data from Japanese and Western women to identify the potential modifying of these factors.

Soy isoflavone intake and breast cancer risk in Japan: From the Takayama study

The effects of soy or isoflavone intake on breast cancer need to be examined further in epidemiologic studies. We assessed the associations of soy and isoflavone intake with breast cancer incidence in a population-based prospective cohort study in Japan. Participants were members from the Takayama study, aged 35 years or older in 1992. The follow-up was conducted from the time of the baseline study (September 1, 1992) to the end of March 2008. Cancer incidence was mainly confirmed through regional population-based cancer registries. Breast cancer was defined as code C50 according to ICD-10. Soy and iso-flavone intakes were assessed with a validated food frequency questionnaire. Using the Cox proportional hazard models, the association of soy and isoflavone intake with breast cancer was assessed after adjustments for age, body mass index, physical activity, smoking, alcohol consumption, education, age at menarche, age at first delivery, menopausal status, number of children and history of hormone replacement therapy. Among the 15,607 women analyzed, 172 had developed breast cancer. The relative risks of postmenopausal breast cancer were lower among women with higher intakes of soy (trend p 5 0.023) and isoflavone (trend p 5 0.046), although the relative risks of premenopausal breast cancer were not associated with intakes of soy and isoflavone. Decreased risks of breast cancer were found even among women with a moderate intake of soy and isofla-vone. These results suggested that soy and isoflavone intakes have a protective effect on postmenopausal breast cancer.

Soy, Red Clover, and Isoflavones and Breast Cancer: A Systematic Review

PLoS ONE, 2013

Background: Soy and red clover isoflavones are controversial due to purported estrogenic activity and possible effects on breast cancer. We conducted a systematic review of soy and red clover for efficacy in improving menopausal symptoms in women with breast cancer, and for potential impact on risk of breast cancer incidence or recurrence.

Soy and its isoflavones: the truth behind the science in breast cancer

Anti-cancer agents in medicinal chemistry, 2013

Epidemiological and migratory evidence suggests that dietary soy consumption can lower the risk for breast cancer. The role of soy isoflavones in cancer prevention and promotion is somewhat unclear. There are two views in terms of soy isoflavones and breast cancer. One line of evidence suggests that soy and its isoflavones have exhibited cancer-preventive properties including lengthening the menstrual cycle, altering estrogen metabolism away from cancerous compounds, and demonstrating anti-proliferative properties in vivo. On the contrary, isoflavones found in soy products are suggested to behave as weak estrogens and as such, much speculation surrounds the influence of soy and/or its isoflavones on hormone-receptor-positive cancers. The objective of this review is to present the latest knowledge regarding the role of soy and its isoflavones with the development and advancement of breast cancer, the safety of soy isoflavones for breast cancer survivors, and a comparison of the carci...

Soy, Isoflavones, and Breast Cancer Risk in Japan

JNCI Journal of the National Cancer Institute, 2003

Background: Although isoflavones, such as those found in soy, have been shown to inhibit breast cancer in laboratory studies, associations between consumption of isoflavonecontaining foods and breast cancer risk have been inconsistent in epidemiologic studies. We evaluated the relationship between isoflavone consumption and breast cancer risk among women in the Japan Public Health Center-Based Prospective Study on Cancer and Cardiovascular Diseases (JPHC Study). Methods: In January 1990, 21 852 Japanese female residents (aged 40-59 years) from four public health center areas completed a self-administered questionnaire, which included items about the frequency of soy consumption. Through December 1999 and 209 354 person-years of follow-up, 179 women were diagnosed with breast cancer. Cox proportional hazards regression was used to estimate the relative risks (RRs) and 95% confidence intervals (CIs) for breast cancer in relation to consumption of miso soup, soyfoods, and estimated isoflavones. All statistical tests were two-sided. Results: Consumption of miso soup and isoflavones, but not of soyfoods, was inversely associated with the risk of breast cancer. The associations did not change substantially after adjustment for potential confounders, including reproductive history, family history, smoking, and other dietary factors. Compared with those in the lowest quartile of isoflavone intake, the adjusted RRs for breast cancer for women in the second, third, and highest quartiles were 0.76 (95% CI = 0.47 to 1.2), 0.90 (95% CI = 0.56 to 1.5), and 0.46 (95% CI = 0.25 to 0.84), respectively (P trend = .043). The inverse association was stronger in postmenopausal women (P trend = .006). Conclusion: In a population-based, prospective cohort study in Japan, frequent miso soup and isoflavone consumption was associated with a reduced risk of breast cancer. [

Effect of soy isoflavones on breast cancer recurrence and death for patients receiving adjuvant endo

Appl Surf Sci, 2011

A variety of health benefits in terms of cancer and cardio vascular disease have been attributed to the consumption of soy foods, primarily because of soy isoflavones. 1 Three primary isoflavones account for virtually all of the isoflavones in soy beans: genistein (about 50%), daidzein (about 40%) and glycitein (about 10%). The chemical structure of soy isoflavones is similar to that of estrogens. The isoflavones are therefore considered to be possible selective estrogen receptor modulators, which may bind to estrogen receptors and selectively stimulate or inhibit estrogen-like action in various tissues. 2 Given that soy-based foods are now more frequently consumed than was previously the case, both as an alternative approach to treating the symptoms of menopause and for promoting cardiovascular health, 3,4 concerns have arisen about the intake of these compounds by patients with hormone-sensitive breast cancer, in whom tumour growth depends largely on estrogen. Tamoxifen and anastrozole are commonly used as adjuvant endocrine therapy for hormone-sensitive breast cancer, and these drugs are effective in preventing recurrence and prolonging survival. 5,6 In some experimental studies the inhibitory effects of tamoxifen on growth of implanted mammary tumours were negated by dietary administration of soy isoflavones, 7,8 but in other rodent cancer models, soy food appeared to enhance the beneficial effects of tamoxifen. 9 Little is known about the potential effects of consuming soy isoflavones for patients with breast cancer who are receiving adjuvant endocrine therapy. We used data for a cohort of postoperative patients with breast cancer who were receiving adjuvant endocrine therapy to examine the relation between intake of soy isoflavones and recurrence of breast cancer and death. Methods Study participants From August 2002 to July 2003, we recruited women with a diagnosis of early or local advanced breast cancer who were receiving adjuvant endocrine therapy after surgery at the Cancer Hospital of Harbin Medical University in Harbin, China. We identified potentially eligible patients by reviewing the hospital's pathological diagnosis records after surgery for breast cancer. The institutional review board of Harbin Medical University provided ethics approval. For each patient, we contacted the attending physician to confirm eligibility, and asked the physician to contact the patient on our behalf. Two pathologists independently confirmed the hormonal receptor status of the tumours by reviewing the results of streptavidin peroxidase immunohistochemical staining. The cutoff for positivity was

Effect of Dietary Soy on Breast Cancer Recurrence and Mortality: A Review

Journal of Nutrition & Food Sciences, 2016

As the number of breast cancer survivors rises, interest in lifestyle modifications that can improve survival increases. The role of soy in breast cancer prevention has been studied and debated for years, and the role of soy's bioactive compounds known as isoflavones continues to be a focus of research. This review summarizes the existing epidemiologic data evaluating the effect of dietary soy intake on breast cancer recurrence and mortality. While some concern exists regarding the pro-estrogenic effect of soy as a risk factor for disease relapse, the vast majority of data shows no increase in breast cancer recurrence and mortality with dietary soy intake.