A group of researchers from the Division of Preventive Oncology, Ontario, Canada, evaluated whether intake of phytoestrogens, specifically lignans and isoflavones, were associated with reduced breast cancer risk, using a novel phytoestrogen database.6
Randomly chosen breast cancer patients, aged 25 to 74 years, were identified using the Ontario Cancer Registry (n=3,063) and controls (n=3,430). An epidemiologic and food frequency questionnaire, which was expanded to include phytoestrogen-containing foods, was mailed to all subjects.
Among all women, lignan intake was associated with a reduced breast cancer risk (Q5 vs. Q1 MVOR: 0.81, 95 percent CI: 0.65, 0.99); however, following stratification by body mass index (BMI), this reduction in risk was statistically significant only among overweight women (BMI > 25). Total phytoestrogen intake was also associated with a risk reduction among overweight women only.
Among pre-menopausal women, total phytoestrogen intake was associated with a significant reduction in breast cancer risk among overweight women only (Q5 vs. Q1 MVOR: 0.51, 95 percent CI: 0.30, 0.87). Among postmenopausal women, no statistically significant association was observed between breast cancer risk and isoflavones or lignans.
The researchers concluded lignan intake may be associated with reduced breast cancer risk among pre-menopausal women, with data suggesting BMI modifies the association.
Another study conducted in Bangkok, Thailand, investigated the pretreatment of the phytoestrogen-rich plant, Pueraria mirifica, and its effects on decreasing breast tumor incidence in rats.7 The rats were pretreated with P. mirifica tuberous powder at a dosage of 0, 10, 100 and 1,000 mg/kg BW/day for four consecutive weeks before induction of mammary tumors. Pretreatment of P. mirifica tuberous powder resulted in decreasing of the virulence of tumor development.
Collectively, lignans appear to offer a range of means that positively influence a favorable estrogen balance in the body. Canadian researchers studied the consumption of flaxseed (FS), and its effects in reducing the growth effect on established breast cancer.8
According to this study, FS, rich in lignans, which is metabolized to the mammalian lignans enterolactone (ENL) and enterodiol (END), consistently showed tumor inhibitory effects in a human clinical trial as well as rodent breast cancer models. Using the preclinical athymic mouse postmenopausal breast cancer model, combining FS with soy protein or GEN with END and ENL, was found to negate the tumor stimulatory effects of soy protein or GEN alone.
Antioxidant and anti-tumor effects of hydroxymatairesinol (as HMRlignan™, from Linnea), a lignan isolated from the knots of spruce, were studied in vitro in lipid peroxidation, superoxide and peroxyl radical scavenging, and LDL-oxidation models in comparison with the known synthetic antioxidants Trolox (a watersoluble vitamin E derivative), butylated hydroxyanisol (BHA) and butylated hydroxytoluene (BHT).9
The antitumor activity of HM-3000 was studied in induced rat mammary cancer, showing a positive result – a statistically significant inhibitory effect on tumor growth. In human studies, HM-3000 has been given in single doses, up to 1,350 mg, to healthy male volunteers devoid of treatment-related adverse events. Rapid absorption from the gastrointestinal tract and partial metabolism to enterolactone in humans was observed.
Cruciferous vegetables, the GSTP1 Ile105Val genetic polymorphism, and breast cancer risk1,2,3
Sang-Ah Lee, Jay H Fowke, Wei Lu, Chuangzhong Ye, Ying Zheng, Qiuyin Cai, Kai Gu, Yu-Tang Gao, Xiao-ou Shu and Wei Zheng
1 From the Vanderbilt Epidemiology Center, Vanderbilt University Medical Center, Nashville, TN (S-AL, JHF, CY, QC, XS, and WZ); the Shanghai Center for Disease Control and Prevention, Shanghai, China (WL, YZ, and KG); and the Department of Epidemiology, Shanghai Cancer Institute, Shanghai, China (Y-TG)
Background: Cruciferous vegetables are the primary source of isothiocyanates and other glucosinolate derivatives that are known to induce phase II detoxifying enzymes, including glutathione S-transferases (GSTs).
Objective: We investigated the independent and combined effects of cruciferous vegetable intake and the GSTP1 Ile105Val genetic polymorphism on breast cancer risk.
Design: Analyses included 3035 cases and 3037 population controls who were participating in the Shanghai Breast Cancer Study and for whom diet and genetic data were complete (87% of cases and 85% of controls).
Results: With the use of multivariate logistic regression, the GSTP1 Val/Val genotype was significantly associated with greater breast cancer risk (OR = 1.50; 95% CI: 1.12, 1.99). The association was significantly greater in premenopausal women (OR = 1.69; 95% CI: 1.17, 2.43) than in postmenopausal women (OR = 1.20; 95% CI: 0.74, 1.92).
Total cruciferous vegetable intake was not significantly associated with breast cancer risk, although subjects reporting greater turnip (P for trend < 0.001) and Chinese cabbage (P for trend = 0.049) intakes had a significantly lower postmenopausal breast cancer risk.
Women with the GSTP1 Val/Val genotype and low cruciferous vegetable intake had a breast cancer risk 1.74-fold (95% CI: 1.13, 2.67) that of women with the Ile/Ile or Ile/Val genotype. This effect of low cruciferous vegetable intake and the Val/Val genotype was seen predominantly among premenopausal women (OR = 2.08; 95% CI = 1.20, 3.59).
Conclusions: Cruciferous vegetable intake consistent with high isothiocyanate exposure may reduce breast cancer risk. Cruciferous vegetable intake also may ameliorate the effects of the GSTP1 genotype.
Breast Health - Nutritional Support
Linear Mode
