Phytoestrogens and Indicators of Breast Cancer Prognosis (original) (raw)
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Implications of Phytoestrogen Intake for Breast Cancer
CA: A Cancer Journal for Clinicians, 2007
Phytoestrogens are a group of plant-derived substances that are structurally or functionally similar to estradiol. Interest in phytoestrogens has been fueled by epidemiologic data that suggest a decreased risk of breast cancer in women from countries with high phytoestrogen consumption. Women with a history of breast cancer may seek out these "natural" hormones in the belief that they are safe or perhaps even protective against recurrence. Interpretation of research studies regarding phytoestrogen intake and breast cancer risk is hampered by differences in dietary measurement, lack of standardization of supplemental sources, differences in metabolism amongst individuals, and the retrospective nature of much of the research in this area. Data regarding the role of phytoestrogens in breast cancer prevention is conflicting, but suggest early exposure in childhood or early adolescence may be protective. In several placebo-controlled randomized trials among breast cancer survivors, soy has not been found to decrease menopausal symptoms. There is very little human data on the role of phytoestrogens in preventing breast cancer recurrence, but the few studies conducted do not support a protective role. There is in vivo animal data suggesting the phytoestrogen genistein may interfere with the inhibitive effects of tamoxifen on breast cancer cell growth. (CA Cancer
Phytoestrogens and Breast Cancer Risk
Breast Cancer Research and Treatment, 2003
Phytoestrogens are natural plant substances. The three main classes are isoflavones, coumestans, and lignans. Phytoestrogens have anticarcinogenic potential, but they have also significant estrogenic properties. For an evaluation of the effect of phytoestrogens on breast cancer risk we reviewed the analytical epidemiological data. A total of 18 studies were included . Up to now, there are 13 studies that have assessed the direct relation between the individual dietary intake of soy products and the risk of breast cancer . Overall, results do not show protective effects, with the exception maybe for women who consume phytoestrogens at adolescence or at very high doses . Only four of these 13 studies are prospective, and none of them found statistically significant breast cancer reductions. Four studies assessed urinary isoflavones excretion in relation to breast cancer . Three of these are case control studies , where excretion was measured after breast cancer occurrence and thus seriously limiting causal interpretation of the results. The only prospective study with urinary measurements before breast cancer occurrence was done in a Dutch postmenopausal population and showed a non-significant breast cancer risk reduction for high excretion . Three studies measured enterolactone (lignan): two case control studies reported a preventive effect on breast cancer risk , but the only prospective study did not . In conclusion, few prospective studies (n = 5) were done to assess the effects of phytoestrogens on breast cancer risk. None of them found protective effects. However, these prospective studies did not focus on 'age at consumption', which seems to be important based on results from dietary case control studies done so far.
Maturitas, 2013
DietCompLyf is a multi-centre prospective study designed to investigate associations between phytoestrogensnaturally occurring plant compounds with oestrogenic properties-and other diet and lifestyle factors with breast cancer recurrence and survival. 3159 women with grade I-III breast cancer were recruited 9-15 months postdiagnosis from 56 UK hospitals. Detailed information on clinico-pathological, diet, lifestyle and quality of life is collected annually up to 5 years. Biological samples have also been collected as a resource for subsequent evaluation. The characteristics of the patients and associations between pre-diagnosis intake of phytoestrogens (isoflavones and lignans; assessed using the EPIC-Norfolk UK 130 question food frequency questionnaire) and breast cancer (i) risk factors and (ii) prognostic factors are described for 1797 women who had complete data for all covariates and phytoestrogens of interest. Isoflavone intakes were higher in the patients who were younger at diagnosis, in the non-smokers, those who had breast-fed and those who took supplements. Lignan intakes were higher in patients with a higher age at diagnosis, in ex-smokers, those who had breast-fed, who took supplements, had a lower BMI at diagnosis, lower age at menarche and were nulliparous. No significant associations between pre-diagnosis phytoestrogen intake and factors associated with improved breast cancer prognosis were observed. The potential for further exploration of the relationship between phytoestrogens and breast cancer recurrence and survival, and for the establishment of evidence to improve dietary and lifestyle advice offered to patients following breast cancer diagnosis using DietCompLyf data is discussed.
Dietary phytoestrogens and breast cancer risk
The American journal of clinical nutrition, 2004
A high intake of phytoestrogens, particularly isoflavones, has been suggested to decrease breast cancer risk. Results from human studies are inconclusive. We investigated the association between phytoestrogen intake and breast cancer risk in a large prospective study in a Dutch population with a habitually low phytoestrogen intake. The study population consisted of 15 555 women aged 49-70 y who constituted a Dutch cohort of the European Prospective Investigation into Cancer and Nutriton (EPIC; 1993-1997). Data concerning habitual dietary intake in the preceding year were obtained by using a validated food-frequency questionnaire. The content of isoflavones and lignans in relevant food items was estimated through a literature search, the use of food-composition tables, and contact with experts. Newly diagnosed breast cancer cases up to 1 January 2001 were identified through linkage with the Comprehensive Cancer Center Middle Netherlands. Hazard ratios for the disease were estimated b...
Phytoestrogen Consumption and Breast Cancer Risk in a Multiethnic Population
2000
Research on the relation between phytoestrogens and breast cancer risk has been limited in scope. Most epidemiologic studies have involved Asian women and have examined the effects of traditional soy foods (e.g., tofu), soy protein, or urinary excretion of phytoestrogens. The present study extends this research by examining the effects of a spectrum of phytoestrogenic compounds on breast cancer risk
The Journal of nutrition, 2008
Results from epidemiological and experimental studies indicate that phytoestrogens may protect against breast cancer. Because one of the biological effects of phytoestrogens is probably estrogenic, it's possible that the preventive effect on breast cancer differs by estrogen receptor (ER) or progesterone receptor (PR) status of the tumor. We evaluated the associations between dietary phytoestrogen (isoflavonoids, lignans, and coumestrol) intake and risk of breast cancer and whether the ER/PR statuses of the tumor influence this relationship. In 1991-2 a prospective population-based cohort study among Swedish pre- and postmenopausal women was performed, making questionnaire data available for 45,448 women. A total of 1014 invasive breast cancers were diagnosed until December 2004. Cox proportional hazards models were performed to estimate multivariate risk ratios, 95% CI for associations with risk of breast cancer. Intakes of lignan, isoflavonoid, or coumestrol were not associate...
Nutrition Research, 2006
Phytoestrogens are natural estrogen-like plant substances. The possible protective effect of phytoestrogens on cancer risk, particularly on hormone-related cancers, has been the focus of many epidemiologic studies during the last 2 decades. We performed a qualitative review of the epidemiologic literature published in the English language and identified on MEDLINE from 1966 until 24 September 2006 on (1) dietary intake of soy, isoflavones, or lignans; (2) urinary excretion of isoflavones or lignans; (3) blood measurements of isoflavones or lignans in relation to breast, prostate, and endometrial cancer risk. Epidemiologic data do seem to support a small protective effect of isoflavones on breast cancer risk, although timing of exposure and the mechanisms of isoflavones at physiologic levels need to be further explored. The epidemiologic evidence to date is conflicting regarding lignans and breast cancer, but recent studies suggest that the effect may be restricted to premenopausal women, differ by estrogen receptor status, and be modified by diet-gene interactions. The 3 case-control studies on dietary intake of phytoestrogens and endometrial cancer risk have provided some evidence for a protective effect, but more prospective data are needed. There is some epidemiologic evidence for a protective effect of soy or isoflavones on prostate cancer, but corresponding data for lignans are inconclusive. Recent data indicate that diet-gene interactions may modify the effect of phytoestrogens on prostate cancer risk. Prospective studies on dietary lignans in relation to prostate cancer risk are lacking. Enterolactone Cases: 25.2 nmol/L Controls: 24.0 nmol/L Highest vs lowest quartile Premenopausal: 0.73 (0.34-1.59) Postmenopausal: 1.22 (0.69-2.16) Crude OR a Boccardo et al, 2004 [48] Historical cohort, 383 Italian women with palpable cysts Enterolactone Cases and controls: 19.6 nmol/L Highest vs lowest quartile: 0.38 (0.09-1.67) Age at cyst aspiration, family history of BC, and cyst type Zeleniuch-Jacquotte et al, 2004 [70] 417 cases, 417 controls (nested), American Enterolactone Cases: 18.5 nmol/L Controls: 17.2 nmol/L Highest vs lowest quintile Premenopausal: 1.6 (0.7-3.4) Postmenopausal: 1.0 (0.5-2.1) Age at menarche, family of BC, nulliparity, age at first full-term birth, height, and BMI Grace et al, 2004 [35] 89 cases (pre-and postmenopausal) 181 controls (nested), British Enterodiol, enterolactone Mean for whole study population (ng/mL) Enterodiol: 0.4 Enterolactone: 3.8 Highest vs lowest tertile Enterodiol: 0.91 (0.74-1.13) Enterolactone: 1.00 (0.82-1.20) BMI, menopausal status, parity, HRT, smoking, family history of BC, and saturated fat intake Olsen et al, 2004 [49] 381 cases (postmenopausal), 381 controls (nested), Danish Enterolactone per 20 mol/L increment All women: 0.93 (0.86-1.01) ER-a+ women: 0.97 (0.88-1.06) ER-aÀ women: 0.71 (0.53-0.94) Age, HRT, education, alcohol intake, parity, smoking, BMI and age at first birth Piller et al, 2006 [40] 220 cases (premenopausal) and 237 age-matched controls, German (subsample) [34] Enterolactone Cases: 6.3 nmol/L b Controls: 9.7 nmol/L b Q1: 1.0 (ref) Q2: 0.91 (0.45-1.82) Q3: 0.60 (0.36-1.02) Q4: 0.38 (0.17-0.85) P for trend .007
Plasma Phytoestrogens and Subsequent Breast Cancer Risk
Journal of Clinical Oncology, 2007
Phytoestrogens are plant compounds that are structurally and functionally similar to mammalian estrogens. By competing for estrogen receptors, phytoestrogens possibly inhibit binding of the more potent endogenous estrogens and decrease their potential effects on breast cancer risk. We investigated the association between plasma phytoestrogen levels and breast cancer risk in a prospective manner.
Cancer Causes & Control, 2004
Objective: This study investigates whether intake of phyto-oestrogens is associated with breast cancer risk in South Asian women from the Indian subcontinent, whose diet is rich in pulses and vegetables but poor in soyfoods. Methods: A total of 240 South Asian breast cancer cases living in England and 477 age-matched population-based controls were recruited into the study. Dietary intake was measured using a validated food frequency questionnaire. Conditional logistic regression models were used to estimate the effect of phyto-oestrogen intake on breast cancer risk. Results: After adjustment for known breast cancer risk factors and total energy intake, there was moderate evidence of a dose-effect response in the odds of breast cancer with isoflavone intake (p-value for trend 0.08), with women in the top quartile having approximately half the odds of breast cancer of those in the bottom one (odds ratio (OR) 0.58, 95% confidence interval (CI) 0.33, 1.00) but with no reductions in the odds for women in the second and third quartiles. The ORs for second, third and highest quartiles of total lignan intake compared to the lowest were 0.78 (95% CI 0.48, 1.26), 0.74 (0.46, 1.19) and 0.66 (0.41, 1.07), respectively, again with moderate evidence of a linear dose-effect response (p-value for trend 0.09). Further adjustment for non-startch polysaccharides (NSP) intake slightly weakened the phyto-oestrogens-breast cancer associations. Conclusions: These findings are consistent with the possibility that high phyto-oestrogen intake may protect against breast cancer, but further research is required to confirm this hypothesis.