Meta-analyses of lignans and enterolignans in relation to breast cancer risk.

BACKGROUND: Epidemiologic studies that examined whether lignans, the most important class of phytoestrogens in the Western diet, protect against breast cancer have yielded inconsistent results. OBJECTIVE: In this study, we conducted meta-analyses on the association between lignans and breast cancer risk. DESIGN: We performed a systematic MEDLINE search to identify epidemiologic studies published between 1997 and August 2009. We calculated pooled risk estimates (REs) for total lignan exposure, dietary lignan intake, enterolignan exposure, and blood or urine concentrations of enterolactone and according to menopausal and estrogen receptor (ER) status of tumors. RESULTS: We included 21 studies (11 prospective cohort studies and 10 case-control studies) in the meta-analyses. Lignan exposure was not associated with an overall breast cancer risk (RE: 0.92; 95% CI: 0.81, 1.02; P for heterogeneity = 0.004). However, in postmenopausal women, high lignan intake was associated with a significant reduced risk of breast cancer (13 studies; RE: 0.86; 95% CI: 0.78, 0.94; P for heterogeneity = 0.32). Breast cancer risk was also inversely associated with enterolignan exposure (4 studies; RE: 0.84; 95% CI: 0.71, 0.97) but not with blood or urine enterolactone concentrations. The associations were not significantly different between ER-status subgroups (6 studies). CONCLUSIONS: High lignan exposure may be associated with a reduced breast cancer risk in postmenopausal women. Additional work is warranted to clarify the association between lignan exposure and breast cancer risk

The association between dietary lignans, phytoestrogen-rich foods, and fiber intake and postmenopausal breast cancer risk: a German case-control study

Contains fulltext : 109759.pdf (publisher's version ) (Closed access)Phytoestrogens are structurally similar to estrogens and may affect breast cancer risk by mimicking estrogenic/antiestrogenic properties. In Western societies, whole grains and possibly soy foods are rich sources of phytoestrogens. A population-based case-control study in German postmenopausal women was used to evaluate the association of phytoestrogen-rich foods and dietary lignans with breast cancer risk. Dietary data were collected from 2,884 cases and 5,509 controls using a validated food-frequency questionnaire, which included additional questions phytoestrogen-rich foods. Associations were assessed using conditional logistic regression. All analyses were adjusted for relevant risk and confounding factors. Polytomous logistic regression analysis was performed to evaluate the associations by estrogen receptor (ER) status. High and low consumption of soybeans as well as of sunflower and pumpkin seeds were associated with significantly reduced breast cancer risk compared to no consumption (OR = 0.83, 95% CI = 0.70-0.97; and OR = 0.66, 95% CI = 0.77-0.97, respectively). The observed associations were not differential by ER status. No statistically significant associations were found for dietary intake of plant lignans, fiber, or the calculated enterolignans. Our results provide evidence for a reduced postmenopausal breast cancer risk associated with increased consumption of sunflower and pumpkin seeds and soybeans

Serum enterolactone and prognosis of postmenopausal breast cancer

Complete miscibility of the intermetallic phases (IPs) SrGa2 and BaGa2 forming the solid solution Sr1-xBaxGa2 is shown by means of X-ray diffraction, thermoanalytical and metallographic studies. Regarding the distances of Sr/Ba sites versus substitution degree, a model of isolated substitution centres (ISC) for up to 10% cation substitution is explored to study the influence on the Ga bonding situation. A combined application of NMR spectroscopy and quantum mechanical (QM) calculations proves the electric field gradient (EFG) to be a sensitive measure of different bonding situations. The experimental resolution is boosted by orientation-dependent NMR on magnetically aligned powder samples, revealing in first approximation two different Ga species in the ISC regimes. EFG calculations using superlattice structures within periodic boundary conditions are in fair agreement with the NMR spectroscopy data and are discussed in detail regarding their application on disordered IPs

Serum enterolactone and prognosis of postmenopausal breast cancer.

Lignans--plant-derived compounds with estrogen-dependent and -independent anticarcinogenic properties--have been associated with postmenopausal breast cancer risk, but data are limited regarding their effect on survival. Dietary lignans are metabolized to enterolignans, which are subsequently absorbed and become bioavailable. We assessed the prognosis of 1,140 postmenopausal patients with breast cancer age 50 to 74 years who were diagnosed between 2002 and 2005. Vital status through the end of 2009 was ascertained via local population registries, and deaths were verified by death certificates. Information on recurrences and secondary tumors was verified by clinical records and attending physicians. Associations of postdiagnostic serum enterolactone (a biomarker for dietary lignans) with overall survival and distant disease-free survival were assessed by using Cox proportional hazards models stratified by age at diagnosis and adjusted for prognostic factors. Median enterolactone levels for deceased patients and those still alive were 17.0 and 21.4 nmol/L, respectively. During a median of 6.1 years of follow-up after diagnosis, 162 deaths were confirmed. Higher serum enterolactone levels were associated with significantly reduced hazard ratios (HRs) for death (HR per 10 nmol/L increment, 0.94; P = .04; HR for the highest quartile, 0.58; 95% CI, 0.34 to 0.99). For distant disease, HR was 0.94 per 10 nmol/L increment (P = .08) and 0.62 (95% CI, 0.35 to 1.09) for the highest quartile. The highest quartile of serum enterolactone was associated with a significantly reduced risk of death only for estrogen receptor-negative tumors (HR, 0.27; 95% CI, 0.08 to 0.87) but not for estrogen receptor-positive tumors (HR, 0.91; 95% CI, 0.45 to 1.84: P for heterogeneity = .09). Postmenopausal patients with breast cancer who have high serum enterolactone levels may have better survival

Estimated enterolignans, lignan-rich foods, and fibre in relation to survival after postmenopausal breast cancer

BACKGROUND: Lignans – oestrogenic substances present in various foods – are associated with postmenopausal breast cancer risk, but not much is known regarding their effects on survival. METHODS: In a follow-up study of 2653 postmenopausal breast cancer patients diagnosed between 2001 and 2005, vital status and causes of death were verified through end of 2009. Hazard ratios (HRs) and 95% confidence intervals (CIs) for estimated enterolignans, lignan-rich foods, and dietary fibre in relation to overall survival (OS) and breast cancer-specific survival (BCSS) were assessed using Cox proportional hazards models stratified by age at diagnosis and adjusted for prognostic/confounding factors. RESULTS: Median follow-up time was 6.4 years, and 321 women died, 235 with breast cancer. High estimated enterolactone and enterodiol levels were associated with significantly lower overall mortality (highest quintile, HR=0.60, 95% CI=0.40–0.89, P(Trend)=0.02 and HR=0.63, 95% CI=0.42–0.95, P(Trend)=0.02, respectively). Fibre intake was also associated with a significantly lower overall mortality. Differentiated by median fibre intake, associations with estimated enterolignans were still evident at low but not high fibre intake. There was no effect modification by oestrogen receptor status and menopausal hormone therapy. CONCLUSION: Postmenopausal breast cancer patients with high estimated enterolignans may have a better survival