Urinary 2-hydroxyestrone/16alpha-hydroxyestrone ratio and risk of breast cancer in postmenopausal women

The WHO claims estrogens are 'carcinogenic': is this true?

Estrogens are in the list of carcinogenic chemicals from the World Health Organization (WHO). However, estrogens require additional factors such as stromal factors or progestogens to increase the ratio of proliferation/apoptosis for initiation of replication errors and consequent mutations to occur. These mutations require at least 5-10 years to develop into clinically detectable cancer, whereby this review is focused on breast cancer. The US National Cancer Institute highlighted a second mechanism of carcinogenicity: certain estrogen metabolites are capable of inducing DNA damage, even in low concentration. They can be assessed in the tissue and circulation. However, those deleterious reactions require excessive unrestricted oxidative cell stress, for example in industrial areas with heavy pollution. We have shown that this can be avoided using transdermal instead of oral estradiol treatment, especially important in smokers. The spectrum of metabolites is also influenced by other exogenous factors such as nutrition, physical activity and certain diseases. Reduction of breast cancer risk as demonstrated in the Women's Health Initiative (WHI) was explained by pro-apoptotic estrogen effects working after a certain 'time gap'. In addition, certain estrogen metabolites are carcinoprotective, if no genetic polymorphisms would impair their beneficial activities. Thus, since additional factors are required for both main pathways of carcinogenicity and because estrogens can even have carcinoprotective effects, we cannot agree with the statement from the WHO.

Current Insight into Novel Delivery Approaches of Resveratrol for Improving Therapeutic Efficacy and Bioavailability with its Clinical Updates

Resveratrol (RSV) is a polyphenolic phytoalexin, and belongs to the stilbene family. RSV has several therapeutic activities such as cardioprotective, anticancer, and antioxidant. Apart from its therapeutic benefits, its pharmacological uses are limited due to low solubility, poor bioavailability, and short biological halflife. A researcher continuously focuses on overcoming the limitations of RSV through nanotechnology platforms to get the optimum health benefits. In this context, nanocarriers are pioneering to overcome these drawbacks. Nanocarriers possess high drug loading capacity, thermal stability, low production cost, longer shelflife, etc. Fortunately, scientists were proficient in delivering resveratrol-based nanocarriers in the present scenario. Nanocarriers can deliver drugs to the target sites without compromising the bioavailability. Thus, this review highlights how the latest nanocarrier systems overcome the shortcomings of RSV, which will be good for improving therapeutic efficacy and bioavailability. Moreover, recent updates on resveratrol-based novel formulations and their clinical trials have been addressed to manage several health-related problems.

Recreational Physical Activity, Sitting, and Androgen Metabolism among Postmenopausal Women in the Women's Health Initiative Observational Study

BACKGROUND

Prolonged sitting and physical inactivity are associated with higher circulating levels of estrogens. It is unknown whether these risk factors are associated with circulating androgens/androgen metabolites, another set of hormones implicated in the etiology of cancers in postmenopausal women.

METHODS

We conducted a cross-sectional analysis of 1,782 postmenopausal women in the Women's Health Initiative Observational Study. Serum concentrations of 12 androgens/androgen metabolites were quantified using liquid chromatography-tandem mass spectrometry. Physical activity and sitting time were self-reported at baseline. We performed linear regression to estimate geometric means (GM) of androgen/androgen metabolite concentrations (pmol/L) according to physical activity and sitting time, adjusting for potential confounders and stratified by menopausal hormone therapy (MHT) use.

RESULTS

Physical activity (≥15 vs. 0 MET-h/wk) was inversely associated with estrogen-to-androgen ratios among never/former MHT users (adj-GM = 37.5 vs. 49.6 unconjugated estrone:androstenedione; 20.2 vs. 30.3 unconjugated estradiol:testosterone; all P _trend ≤ 0.03) but was not associated among current MHT users. Prolonged sitting (≥10 vs. ≤5 h/d) was positively associated with these ratios among both never/former (adj-GM = 44.2 vs. 38.3, P _trend = 0.10; adj-GM = 23.4 vs. 20.2, P _trend = 0.17; respectively) and current MHT users (adj-GM = 197 vs. 147; 105 vs. 75.5; respectively; all P _trend ≤0.02), but the associations were statistically significant among current MHT users only. The associations persisted after adjustment for BMI. After adjustment for adrenal androgens, physical activity and sitting were not associated with androgen metabolites.

CONCLUSIONS

Physical activity and sitting were associated with serum estrogen-to-androgen ratios but not androgen metabolites.

IMPACT

This study contributes to our understanding of the link between physical activity, sitting, and cancer risk in postmenopausal women.

The Steroid Metabolome and Breast Cancer Risk in Women with a Family History of Breast Cancer: The Novel Role of Adrenal Androgens and Glucocorticoids

BACKGROUND

No study has comprehensively examined how the steroid metabolome is associated with breast cancer risk in women with familial risk.

METHODS

We examined 36 steroid metabolites across the spectrum of familial risk (5-year risk ranged from 0.14% to 23.8%) in pre- and postmenopausal women participating in the New York site of the Breast Cancer Family Registry (BCFR). We conducted a nested case-control study with 62 cases/124 controls individually matched on menopausal status, age, and race. We measured metabolites using GC-MS in urine samples collected at baseline before the onset of prospectively ascertained cases. We used conditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) per doubling in hormone levels.

RESULTS

The average proportion of total steroid metabolites in the study sample were glucocorticoids (61%), androgens (26%), progestogens (11%), and estrogens (2%). A doubling in glucocorticoids (aOR = 2.7; 95% CI = 1.3-5.3) and androgens (aOR = 1.6; 95% CI = 1.0-2.7) was associated with increased breast cancer risk. Specific glucocorticoids (THE, THF αTHF, 6β-OH-F, THA, and α-THB) were associated with 49% to 161% increased risk. Two androgen metabolites (AN and 11-OH-AN) were associated with 70% (aOR = 1.7; 95% CI = 1.1-2.7) and 90% (aOR = 1.9; 95% CI = 1.2-3.1) increased risk, respectively. One intermediate metabolite of a cortisol precursor (THS) was associated with 65% (OR = 1.65; 95% CI = 1.0-2.7) increased risk. E1 and E2 estrogens were associated with 20% and 27% decreased risk, respectively.

CONCLUSIONS

Results suggest that glucocorticoids and 11-oxygenated androgens are positively associated with breast cancer risk across the familial risk spectrum.

IMPACT

If replicated, our findings suggest great potential of including steroids into existing breast cancer risk assessment tools.

Health benefits of resveratrol: Evidence from clinical studies

Resveratrol is a polyphenolic nutraceutical that exhibits pleiotropic activities in human subjects. The efficacy, safety, and pharmacokinetics of resveratrol have been documented in over 244 clinical trials, with an additional 27 clinical trials currently ongoing. Resveretrol is reported to potentially improve the therapeutic outcome in patients suffering from diabetes mellitus, obesity, colorectal cancer, breast cancer, multiple myeloma, metabolic syndrome, hypertension, Alzheimer's disease, stroke, cardiovascular diseases, kidney diseases, inflammatory diseases, and rhinopharyngitis. The polyphenol is reported to be safe at doses up to 5 g/d, when used either alone or as a combination therapy. The molecular basis for the pleiotropic activities of resveratrol are based on its ability to modulate multiple cell signaling molecules such as cytokines, caspases, matrix metalloproteinases, Wnt, nuclear factor-κB, Notch, 5'-AMP-activated protein kinase, intercellular adhesion molecule, vascular cell adhesion molecule, sirtuin type 1, peroxisome proliferator-activated receptor-γ coactivator 1α, insulin-like growth factor 1, insulin-like growth factor-binding protein 3, Ras association domain family 1α, pAkt, vascular endothelial growth factor, cyclooxygenase 2, nuclear factor erythroid 2 like 2, and Kelch-like ECH-associated protein 1. Although the clinical utility of resveratrol is well documented, the rapid metabolism and poor bioavailability have limited its therapeutic use. In this regard, the recently produced micronized resveratrol formulation called SRT501, shows promise. This review discusses the currently available clinical data on resveratrol in the prevention, management, and treatment of various diseases and disorders. Based on the current evidence, the potential utility of this molecule in the clinic is discussed.

A randomized, placebo-controlled trial of diindolylmethane for breast cancer biomarker modulation in patients taking tamoxifen

PURPOSE

Diindolylmethane (DIM), a bioactive metabolite of indole-3-carbinol found in cruciferous vegetables, has proposed cancer chemoprevention activity in the breast. There is limited evidence of clinically relevant activity of DIM or long-term safety data of its regular use. A randomized, double-blind, placebo-controlled trial was conducted to determine the activity and safety of combined use of BioResponse DIM® (BR-DIM) with tamoxifen.

METHODS

Women prescribed tamoxifen (n = 130) were randomly assigned oral BR-DIM at 150 mg twice daily or placebo, for 12 months. The primary study endpoint was change in urinary 2/16α-hydroxyestrone (2/16α-OHE1) ratio. Changes in 4-hydroxyestrone (4-OHE1), serum estrogens, sex hormone-binding globulin (SHBG), breast density, and tamoxifen metabolites were assessed.

RESULTS

Ninety-eight women (51 placebo, 47 DIM) completed intervention; compliance with treatment was >91%. BR-DIM increased the 2/16α-OHE1 ratio (+3.2 [0.8, 8.4]) compared to placebo (-0.7 [-1.7, 0.8], P < 0.001). Serum SHBG increased with BR-DIM compared to placebo (+25 ± 22 and +1.1 ± 19 nmol/L, respectively). No change in breast density measured by mammography or by MRI was observed. Plasma tamoxifen metabolites (endoxifen, 4-OH tamoxifen, and N-desmethyl-tamoxifen) were reduced in women receiving BR-DIM versus placebo (P < 0.001). Minimal adverse events were reported and did not differ by treatment arm.

CONCLUSION

In patients taking tamoxifen for breast cancer, daily BR-DIM promoted favorable changes in estrogen metabolism and circulating levels of SHBG. Further research is warranted to determine whether BR-DIM associated decreases in tamoxifen metabolites, including effects on endoxifen levels, attenuates the clinical benefit of tamoxifen.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01391689.

The effect of oral 3,3'-diindolylmethane supplementation on the 2:16α-OHE ratio in BRCA1 mutation carriers

Hormonal exposures are known to influence breast cancer risk among women with a BRCA1 mutation. Thus, dietary factors that increase the 2-hydroxyestrone (OHE):16α-OHE ratio, a biomarker inversely related to breast cancer development, may also influence cancer risk. We conducted a dietary intervention study to evaluate the ability of 300 mg/day of 3,3'-diindolylmethane (DIM) to increase the urinary 2:16α-OHE ratio in 20 women with a BRCA1 mutation. BRCA1 mutation carriers (n = 15) were assigned to receive 300 mg/day of Rx Balance BioREsponse DIM for 4-6 weeks (intervention group) and five BRCA1 mutation carriers did not take DIM (control group). The urinary 2:16α-OHE ratio was assessed at baseline and after 4-6 weeks by immunoassay. There was no significant effect of DIM on the 2:16α-OHE ratio (2.4 at baseline vs. 3.0 after the intervention, P = 0.35). A short dietary intervention with DIM did not significantly increase the 2:16α-OHE ratio in female BRCA1 mutation carriers. Larger studies investigating the effect of dietary or lifestyle interventions on circulating hormone levels in these high-risk women are warranted.

Chemoprevention of Breast Cancer by Dietary Polyphenols

The review will discuss in detail the effects of polyphenols on breast cancer, including both the advantages and disadvantages of the applications of these natural compounds. First, we focus on the characterization of the main classes of polyphenols and then on in vitro and in vivo experiments carried out in breast cancer models. Since the therapeutic effects of the administration of a single type of polyphenol might be limited because of the reduced bioavailability of these drugs, investigations on combination of several polyphenols or polyphenols with conventional therapy will also be discussed. In addition, we present recent data focusing on clinical trials with polyphenols and new approaches with nanoparticles in breast cancer. Besides the clinical and translational findings this review systematically summarizes our current knowledge about the molecular mechanisms of anti-cancer effects of polyphenols, which are related to apoptosis, cell cycle regulation, plasma membrane receptors, signaling pathways and epigenetic mechanisms. At the same time the effects of polyphenols on primary tumor, metastasis and angiogenesis in breast cancer are discussed. The increasing enthusiasm regarding the combination of polyphenols and conventional therapy in breast cancer might lead to additional efforts to motivate further research in this field.

The ratio of the estradiol metabolites 2-hydroxyestrone (2-OHE1) and 16α-hydroxyestrone (16-OHE1) may predict breast cancer risk in postmenopausal but not in premenopausal women: two case-control studies

PURPOSE

Two main estradiol metabolites have different biological behavior with tumorigenic features of 16-OHE1 and antiproliferative characteristics of 2-OHE1. We investigated the ratio of these estradiol metabolites in pre- and postmenopausal patients with breast cancer (BC) within two case-control studies.

METHODS

From 41 premenopausal patients with (cases) and without (controls N = 211) BC and 207 postmenopausal patients with and without BC (N = 206), urine samples were collected. Urine samples were collected prior to surgery and stored at -20 °C until measurement by ELISA. The multiple linear regression test with two interactions was performed to evaluate the influence of different factors on the metabolic ratio.

RESULTS

In premenopausal patients, log ratio of 2-OHE1/16-OHE1 was 0.25 (CI 0.20;0.29) and 0.21 (CI 0.11;0.31) for controls and cases without significant difference. In postmenopausal patients, log ratio was 0.22 (CI 0.17;0.26) and 0.11 (CI 0.07;0.15) in controls and cases, respectively, and was statistically significantly lower (p = 0.0002). Log ratio was significantly influenced by BMI, but only in postmenopausal patients, an increased BMI resulted in a significantly (p < 0.042) decreased ratio.

CONCLUSIONS

Our case control studies suggest that in postmenopausal women a different metabolism of estrogens may play a role in the tumorigenesis of breast cancer. This genetically determined metabolism could be influenced by the exogenic factor BMI. In premenopausal women different hormone levels at different time points of the menstrual cycle may be an explanation that why we could not find an influence of estrogen metabolism.

A pilot clinical study of resveratrol in postmenopausal women with high body mass index: effects on systemic sex steroid hormones

BACKGROUND

Breast cancer risk is partially determined by several hormone-related factors. Preclinical and clinical studies suggested that resveratrol may modulate these hormonal factors.

METHODS

We conducted a pilot study in postmenopausal women with high body mass index (BMI ≥ 25 kg/m2) to determine the clinical effect of resveratrol on systemic sex steroid hormones. Forty subjects initiated the resveratrol intervention (1 gm daily for 12 weeks) with six withdrawn early due to adverse events (AEs). Thirty-four subjects completed the intervention.

RESULTS

Resveratrol intervention did not result in significant changes in serum concentrations of estradiol, estrone, and testosterone but led to an average of 10% increase in the concentrations of sex steroid hormone binding globulin (SHBG). Resveratrol intervention resulted in an average of 73% increase in urinary 2-hydroxyestrone (2-OHE1) levels leading to a favorable change in urinary 2-OHE1/16α-OHE1 ratio. One participant had asymptomatic Grade 4 elevation of liver enzymes at the end of study intervention. Two subjects had Grade 3 skin rashes. The remaining adverse events were Grade 1 or 2 events. The most common adverse events were diarrhea and increased total cholesterol, reported in 30% and 27.5% of the subjects, respectively.

CONCLUSION

We conclude that among overweight and obese postmenopausal women, daily 1 gm dose of resveratrol has favorable effects on estrogen metabolism and SHBG. Further placebo-controlled studies are needed to confirm our findings on these hormone-related breast cancer risk factors and the attribution of the adverse effects observed in the study population.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01370889.

Estrogen metabolism and breast cancer

There is currently accumulating evidence that endogenous estrogens play a critical role in the development of breast cancer. Estrogens and their metabolites have been studied in both pre- and postmenopausal women with more consistent results shown in the latter population, in part because of large hormonal variations during the menstrual cycle and far fewer studies having been performed in premenopausal women. In this review we describe in detail estrogen metabolism and associated genetic variations, and provide a critical review of the current literature regarding the role of estrogens and their metabolites in breast cancer risk.

Association between urinary levels of bisphenol-A and estrogen metabolism in Korean adults

Bisphenol-A (BPA) possesses estrogenic properties both in vitro and in vivo as an endocrine disrupting chemical. Humans experience a long-term and cumulative exposure to BPA. BPA was detectable in 97.3% of 1904 urine specimens from Korean adults. We investigated urinary estrogen concentrations in subjects with low and high BPA concentrations and its possible association with estrogen metabolism. Urine samples were collected from a high BPA concentration group (BPA-H; n=100, 11.05 ± 20.47 μg/g creatinine) and a low BPA concentration group (BPA-L; n=100, 0.70 ± 0.22 μg/g creatinine) from Korea Biomonitoring Program of Hazardous Materials Survey 2009-2010. Urinary estrogens were enzymatically hydrolyzed, extracted, and then derivatized for quantitative analysis by gas chromatography-mass spectrometry. Estrogen levels were higher in the BPA-H group than in the BPA-L group. Concentrations of estrone, 17β-estradiol, and their hydroxylated metabolites in both men and women were significantly higher in the BPA-H group than in the BPA-L group (p<0.04). Furthermore, in the BPA-H group, estrogen metabolism to 4-hydroxy-estrone and 4-hydroxy-17β-estradiol was more active than that to 2-hydroxy-estrone and 2-hydroxy-17β-estradiol. Although single measurement and/or single spot urine samples limit the measurement of long-term exposure to BPA, we found significant differences of estrogen metabolism in the BPA-H and the BPA-L groups. The increase of hydroxyestrogens, especially 4-hydroxyestrogens, can be an important factor resulting negative effects of prolonged exposure to BPA.

S-(-)equol producing status not associated with breast cancer risk among low isoflavone-consuming US postmenopausal women undergoing a physician-recommended breast biopsy

Soy foods are the richest sources of isoflavones, mainly daidzein and genistein. Soy isoflavones are structurally similar to the steroid hormone 17β-estradiol and may protect against breast cancer. S-(-)equol, a metabolite of the soy isoflavone daidzein, has a higher bioavailability and greater affinity for estrogen receptor β than daidzein. Approximately one-third of the Western population is able to produce S-(-)equol, and the ability is linked to certain gut microbes. We hypothesized that the prevalence of breast cancer, ductal hyperplasia, and overall breast pathology will be lower among S-(-)equol producing, as compared with nonproducing, postmenopausal women undergoing a breast biopsy. We tested our hypothesis using a cross-sectional study design. Usual diets of the participants were supplemented with 1 soy bar per day for 3 consecutive days. Liquid chromatography-multiple reaction ion monitoring mass spectrometry analysis of urine from 143 subjects revealed 25 (17.5%) as S-(-)equol producers. We found no statistically significant associations between S-(-)equol producing status and overall breast pathology (odds ratio [OR], 0.68; 95% confidence interval [CI], 0.23-1.89), ductal hyperplasia (OR, 0.84; 95% CI, 0.20-3.41), or breast cancer (OR, 0.56; 95% CI, 0.16-1.87). However, the mean dietary isoflavone intake was much lower (0.3 mg/d) than in previous reports. Given that the amount of S-(-)equol produced in the gut depends on the amount of daidzein exposure, the low soy intake coupled with lower prevalence of S-(-)equol producing status in the study population favors toward null associations. Findings from our study could be used for further investigations on S-(-)equol producing status and disease risk.

Comparison of metabolic ratios of urinary estrogens between benign and malignant thyroid tumors in postmenopausal women

Background

Estrogen metabolism may be associated with the pathophysiological development of papillary thyroid carcinoma (PTC).

Methods

To evaluate the differential estrogen metabolism between benign and malignant PTCs, estrogen profiling by gas chromatography–mass spectrometry was applied to urine samples from postmenopausal patients with 9 benign tumors and 18 malignant stage I and III/IV PTCs.

Results

The urinary concentration of 2-methoxyestradiol was significantly lower in the stage I malignant patients (3.5-fold; P < 0.025) than in the benign group. The metabolic ratios of 16α-OH-estrone/estrone and estriol/estradiol, which are responsible for 16α-hydroxylase activity, were increased more than 2.5-fold in the advanced-stage malignant PTC (P < 0.02 each). The more than 6.2-fold decrease in the urinary 2-/16α-hydroxylase ratio in stage III/IV malignant PTC was consistent with the ratio in postmenopausal patients with endocrine gland cancers. In addition, reductive 17β-hydroxysteroid dehydrogenase (17β-HSD; estradiol/estrone or estriol/16α-OH-estrone) was present at significantly higher levels in subjects with stage III/IV malignant PTCs than in benign subjects (>3.5-fold difference; P < 0.002). In particular, the estriol/16α-OH-estrone ratio differentiated between the benign and early-stage malignant patients (P < 0.01).

Conclusions

Increased 16α-hydroxylation and/or a decreased 2-/16α-ratio, as well increased reductive 17β-HSD, with regard to estrogen metabolism could provide potential biomarkers. The devised profiles could be useful for differentiating malignant thyroid carcinomas from benign adenomas in postmenopausal women.

Multi-nutrient supplement improves hormone ratio associated with cancer risk

BACKGROUND

Gynecological cancers are among the most common in women and are directly related to a variety of hormonal factors. One potential risk factor associated with developing a gynecological malignancy is the ratio of two hormone metabolites, 2-Hydroxyestrone (2-HE) and 16alpha-Hydroxyestrone (16alpha-HE). A number of botanical constituents such as indoles, flavonoids, and resveratrol have been shown to have a favorable effect on the metabolic pathways that affect this ratio. The present study was designed to evaluate if a multi-nutrient supplement containing targeted botanical constituents would affect the 2-HE/16 alpha-HE ratio in middle-aged women.

METHODS

A retrospective analysis was performed on 76 female patients (mean age 54 years) who received 2-HE/16 alpha-HE ratio assessments at two separate time points. The ratio assessment was part of standard care for women who presented with risk indicators associated with a high proliferative state. All patients who completed pre and post assessments were included. Sixty-five of the patients received a multi-nutrient supplement, Lucentia Peak, during the study period. Eleven patients chose not to take the supplement, but did receive ratio assessments at similar time points as the treatment group, allowing for between group comparisons. Paired t-tests were used to compare the changes in the 2-HE and 16alpha-HE measures as well as their ratio, both within groups and between groups.

RESULTS

The results demonstrated a significant increase in the 2-HE/16alpha-HE ratio in the treated group (pre 0.38 to post 0.57, p<0.0001), and was significantly different (p=0.02) compared to the change in the control group (pre 0.65 to post 0.64). This change appears to be mediated primarily by an increase in the 2-HE level. Individually, 54 patients given Lucentia Peak had increased ratios while 11 patients had a decrease. In the control group, 3 patients had an increase in their ratio and 8 patients had a decrease.

CONCLUSIONS

The results demonstrated that women receiving the Lucentia Peak multi-nutrient supplement had significant increases in their 2-HE:16alpha-HE ratio, which appears to be mediated primarily by increasing the 2-HE levels. These results suggest further research on phytonutrients that might positively affect estrogen metabolism is warranted.

Urinary estrogen metabolites and breast cancer: a combined analysis of individual level data

BACKGROUND

Circulating estrogens are associated with increased breast cancer risk, yet the role of estrogen metabolites in breast carcinogenesis remains unclear. This combined analysis of 5 published studies evaluates urinary 2-hydroxyestrone (2-OHE1), 16α-hydroxyestrone (16α-OHE1), and their ratio (2:16α-OHE1) in relation to breast cancer risk.

METHODS

Primary data on 726 premenopausal women (183 invasive breast cancer cases and 543 controls) and 1,108 postmenopausal women (385 invasive breast cancer cases and 723 controls) were analyzed. Urinary estrogen metabolites were measured using enzyme linked immunosorbent assays. Study-specific and combined multivariable adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated based on tertiles of estrogen metabolites. Multinomial logistic regression models were fit according to hormone receptor status.


RESULTS

Higher premenopausal 2:16α-OHE1 was suggestive of reduced breast cancer risk overall (study-adjusted ORIIIvsI=0.80; 95% CI: 0.49-1.32) and for estrogen receptor negative (ER-) subtype (ORIIIvsI=0.33; 95% CI: 0.13-0.84). Among postmenopausal women, 2:16α-OHE1 was unrelated to breast cancer risk (study-adjusted ORIIIvsI=0.93; 95% CI: 0.65-1.33); however, the association between 2-OHE1 and risk varied by body mass index (p-interaction=0.003).

CONCLUSIONS

Premenopausal urinary 2:16α-OHE1 may play a role in breast carcinogenesis; however, larger studies are needed. Our findings do not support reduced breast cancer risk with higher postmenopausal 2:16α-OHE1 overall, although obesity may modify associations with 2-OHE1.

Estrogen metabolism and mammographic density in postmenopausal women: a cross-sectional study

BACKGROUND

Prospective studies have consistently found that postmenopausal breast cancer risk increases with circulating estrogens; however, findings from studies of estrogens and mammographic density (MD), an intermediate marker of breast cancer risk, have been inconsistent. We investigated the cross-sectional associations of urinary estrogens, and their 2-, 4-, and 16-hydroxylated metabolites with MD.

METHODS

Postmenopausal women without breast cancer (n = 194), ages 48 to 82 years, and reporting no current menopausal hormone therapy use were enrolled at a clinic in Western NY in 2005. Urinary estrogens and estrogen metabolites were measured using mass spectrometry. Percent MD and dense area (cm(2)) were measured using computer-assisted analyses of digitized films. Linear regression models were used to estimate associations of log-transformed estrogen measures with MD while adjusting for age, body mass index (BMI), parity, and past hormone therapy use.

RESULTS

Urinary concentrations of most individual estrogens and metabolites were not associated with MD; however, across the interdecile range of the ratio of parent estrogens (estrone and estradiol) to their metabolites, MD increased by 6.8 percentage points (P = 0.02) and dense area increased by 10.3 cm(2) (P = 0.03). Across the interdecile ranges of the ratios of 2-, 4-, and 16-hydroxylation pathways to the parent estrogens, MD declined by 6.2 (P = 0.03), 6.4 (P = 0.04), and 5.7 (P = 0.05) percentage points, respectively. All associations remained apparent in models without adjustment for BMI.

CONCLUSION

In this study of postmenopausal women, less extensive hydroxylation of parent estrogens was associated with higher MD.

IMPACT

Hydroxylation of estrogens may modulate postmenopausal breast cancer risk through a pathway involving MD.

Hormone therapy, estrogen metabolism, and risk of breast cancer in the Women's Health Initiative Hormone Therapy Trial

BACKGROUND

In the Women's Health Initiative Hormone Trials (WHI-HT), breast cancer risk was increased with estrogen plus progestin (E+P) but not with unopposed estrogen (E-alone). We hypothesized that E+P would preferentially metabolize to 16α-hydroxyestrone (16α-OHE1) rather than 2-hydroxyestrone (2-OHE1), and that breast cancer risk would be associated with baseline and 1 year changes in estrogen metabolites: positively for 16α-OHE1 levels and negatively for levels of 2-OHE-1 and the 2:16 ratio.

METHODS

In a prospective case-control study nested in the WHI-HT, 845 confirmed breast cancer cases were matched to 1,690 controls by age and ethnicity. Using stored serum, 2-OHE1 and 16α-OHE1 levels were measured by enzyme immunoassay at baseline, and for those randomized to active treatment (n = 1,259), at 1 year.

RESULTS

The 1-year increase in 16α-OHE1 was greater with E+P than E-alone (median 55.5 pg/mL vs. 43.5 pg/mL, P < 0.001), but both increased 2-OHE1 by ∼300 pg/mL. Breast cancer risk was modestly associated with higher baseline levels of 2-OHE1 and the 2:16 ratio, and for estrogen receptor+/progesterone+ cases only, higher baseline 16α-OHE1 levels. For those randomized to active treatment, breast cancer risk was associated with greater increase in 2-OHE-1 and the 2:16 ratio, but associations were not significant.

CONCLUSIONS

Although E+P modestly increased 16α-OHE1 more than E-alone, increase in 16α-OHE1 was not associated with breast cancer.

IMPACT

Study results do not explain differences between the WHI E+P and WHI E-alone breast cancer results but metabolism of oral HT, which may explain smaller than expected increase in breast cancer compared with endogenous estrogens.

Association between reproductive factors and urinary estrogens and estrogen metabolites in premenopausal women

BACKGROUND

Little is known about relationships among reproductive factors, estrogens and estrogen metabolites (jointly referred to as EM), and estrogen metabolism patterns.

METHODS

In a cross-sectional analysis, we examined the associations of age at menarche, menstrual cycle length and regularity, parity, age at first and last birth, breastfeeding, and duration of and time since use of oral contraceptives with mid-luteal phase urinary EM in a sample of 603 premenopausal women, ages 33 to 51 years, within the Nurses' Health Study II (NHSII). Fifteen individual urinary EMs were measured with liquid chromatography/tandem mass spectrometry (LC/MS-MS) and analyzed both individually and in metabolic pathways.

RESULTS

Compared with women with extremely regular cycles, those with irregular cycles had lower levels of total EM (percent difference = 24%; P(trend) = 0.01), estradiol (23%; P(trend) = 0.02), and 16-hydroxylation pathway EM (32%; P(trend) < 0.01). Longer menstrual cycles were associated with higher levels of estrone (percent difference ≥32 vs. <26 days: 25%; P(trend) = 0.03), estradiol (24%; P(trend) = 0.01), and 16-hydroxylation pathway EM (22%; P(trend) = 0.02). Among parous women, older age at first birth was associated with lower 16-hydroxylation pathway EM (percent difference age at first birth >35 vs. ≤25 years: 20%; P(trend) = 0.02). The other reproductive factors were not statistically significantly associated with individual urinary EM or EM pathways.

CONCLUSIONS AND IMPACT

These data, based on a LC/MS-MS assay with high specificity and precision, provide an initial, comprehensive evaluation of the associations between reproductive factors and estrogen metabolism patterns.

[Interactions of insulin and estrogen in the regulation of cell proliferation and carcinogenesis]

Equilibrium of sexual steroids and metabolic processes has close correlations. Insulin is a potent regulator of human sexual steroid hormone production and modulates their signals at receptor level. Insulin resistance and excessive insulin production provoke hyperandrogenism and estrogen deficiency in women resulting not only in anovulatory dysfunction but also a high risk for cardiovascular diseases and cancer. Physiologic functions of all female organs have higher estrogen demand as compared with men. In healthy women estrogen predominance against androgens is a favor in their reproductive period, which means a strong defense against insulin resistance and its complications. However, in postmenopausal cases the increasing prevalence of insulin resistance and type-2 diabetes associated with estrogen deficiency and androgen excess, result in a gender specific higher risk for precancerous lesions and cancer as compared with men. Estrogen has beneficial effect on the energy metabolism, glucose homeostasis and on the lipid metabolism of liver and of peripheral tissues as well. A moderate or severe decrease in serum estrogen level enhances the prevalence of insulin resistant states. In premenopausal women long or irregular menstrual cycles are predictors for the risk of insulin resistance and type-2 diabetes. Moreover, in postmenopausal estrogen deficient cases elevated fasting glucose, increased body weight and abdominal fat deposition are often observed progressively with age in correlation with an impaired glucose tolerance. In the rare cases of estrogen deficient men severe type-2 diabetes seems to be a characteristic complication. Upon becoming familiar with the cancer risk of insulin resistance and estrogen deficiency, there would be plenty of possibilities for primary cancer prevention. In patients with cancer the treatment of hormonal and metabolic disturbances may become effective adjuvant therapy.

Urinary estrogens and estrogen metabolites and subsequent risk of breast cancer among premenopausal women

Endogenous estrogens and estrogen metabolism are hypothesized to be associated with premenopausal breast cancer risk but evidence is limited. We examined 15 urinary estrogens/estrogen metabolites and breast cancer risk among premenopausal women in a case-control study nested within the Nurses' Health Study II (NHSII). From 1996 to 1999, urine was collected from 18,521 women during the mid-luteal menstrual phase. Breast cancer cases (N = 247) diagnosed between collection and June 2005 were matched to two controls each (N = 485). Urinary estrogen metabolites were measured by liquid chromatography-tandem mass spectrometry and adjusted for creatinine level. Relative risks (RR) and 95% confidence intervals (CI) were estimated by multivariate conditional logistic regression. Higher urinary estrone and estradiol levels were strongly significantly associated with lower risk (top vs. bottom quartile RR: estrone = 0.52; 95% CI, 0.30-0.88; estradiol = 0.51; 95% CI, 0.30-0.86). Generally inverse, although nonsignificant, patterns also were observed with 2- and 4-hydroxylation pathway estrogen metabolites. Inverse associations generally were not observed with 16-pathway estrogen metabolites and a significant positive association was observed with 17-epiestriol (top vs. bottom quartile RR = 1.74; 95% CI, 1.08-2.81; P(trend) = 0.01). In addition, there was a significant increased risk with higher 16-pathway/parent estrogen metabolite ratio (comparable RR = 1.61; 95% CI, 0.99-2.62; P(trend) = 0.04). Other pathway ratios were not significantly associated with risk except parent estrogen metabolites/non-parent estrogen metabolites (comparable RR = 0.58; 95% CI, 0.35-0.96; P(trend) = 0.03). These data suggest that most mid-luteal urinary estrogen metabolite concentrations are not positively associated with breast cancer risk among premenopausal women. The inverse associations with parent estrogen metabolites and the parent estrogen metabolite/non-parent estrogen metabolite ratio suggest that women with higher urinary excretion of parent estrogens are at lower risk.

Urinary estrogen metabolites during a randomized soy trial

One of the hypothesized protective mechanisms of soy against breast cancer involves changes in estrogen metabolism to 2-hydroxy (OH) and 16α-OH estrogens. The current analysis examined the effect of soy foods on the 2:16α-OH E(1) ratio among premenopausal women during a randomized, crossover intervention study; women were stratified by equol producer status, a characteristic thought to enhance the protective effects of soy isoflavones. The study consisted of a high-soy diet with 2 soy food servings/day and a low-soy diet with <3 servings of soy/wk for 6 mo each; estrogen metabolites were measured in 3 overnight urines (baseline and at the end of the low- and high-soy diet) using gas chromatography mass spectrometry for the 82 women who completed the study. Urinary isoflavonoids were assessed by liquid chromatography mass spectrometry. When applying mixed models, the 2:16α-OH E(1) ratio increased (P = 0.05) because of a nonsignificant decrease in 16α-OH E(1) (P = 0.21) at the end of the high-soy diet. Similar nonsignificant increases in the 2:16α-OH E(1) ratio were observed in equol producers (P = 0.13) and nonproducers (P = 0.23). These findings suggest a beneficial influence of soy foods on estrogen metabolism regardless of equol producer status.

Estrogen metabolism and risk of breast cancer in postmenopausal women

BACKGROUND

Estrogens are recognized causal factors in breast cancer. Interindividual variation in estrogen metabolism may also influence the risk of breast cancer and could provide clues to mechanisms of breast carcinogenesis. Long-standing hypotheses about how estrogen metabolism might influence breast cancer have not been adequately evaluated in epidemiological studies because of the lack of accurate, reproducible, and high-throughput assays for estrogen metabolites.

METHODS

We conducted a prospective case-control study nested within the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO). Participants included 277 women who developed invasive breast cancer (case subjects) and 423 matched control subjects; at PLCO baseline, all subjects were aged 55-74 years, postmenopausal and not using hormone therapy, and provided a blood sample. Liquid chromatography-tandem mass spectrometry was used to measure serum concentrations of 15 estrogens and estrogen metabolites, in unconjugated and conjugated forms, including the parent estrogens, estrone and estradiol, and estrogen metabolites in pathways defined by irreversible hydroxylation at the C-2, C-4, or C-16 positions of the steroid ring. We calculated hazard ratios (HRs) approximating risk in highest vs lowest deciles of individual estrogens and estrogen metabolites, estrogens and estrogen metabolites grouped by metabolic pathways, and metabolic pathway ratios using multivariable Cox proportional hazards models. All statistical tests were two-sided.

RESULTS

Nearly all estrogens, estrogen metabolites, and metabolic pathway groups were associated with an increased risk of breast cancer; the serum concentration of unconjugated estradiol was strongly associated with the risk of breast cancer (HR = 2.07, 95% confidence interval [CI] = 1.19 to 3.62). No estrogen, estrogen metabolite, or metabolic pathway group remained statistically significantly associated with the risk of breast cancer after adjusting for unconjugated estradiol. The ratio of the 2-hydroxylation pathway to parent estrogens (HR = 0.66, 95% CI = 0.51 to 0.87) and the ratio of 4-hydroxylation pathway catechols to 4-hydroxylation pathway methylated catechols (HR = 1.34, 95% CI = 1.04 to 1.72) were statistically significantly associated with the risk of breast cancer and remained so after adjustment for unconjugated estradiol.

CONCLUSIONS

More extensive 2-hydroxylation of parent estrogens is associated with lower risk, and less extensive methylation of potentially genotoxic 4-hydroxylation pathway catechols is associated with higher risk of postmenopausal breast cancer.

Estrogen activity as a preventive and therapeutic target in thyroid cancer

Thyroid cancer is the most common endocrine-related cancer with increasing incidences during the last five years. Interestingly, according to the American Thyroid Association, the incidences of thyroid proliferative diseases occur four to five times more in women than in men with the risk of developing thyroid disorders being one in every eight females. Several epidemiological studies have suggested a possible correlation between incidences of thyroid malignancies and hormones but the precise contribution of estrogen in thyroid proliferative disease initiation, and progression is not well understood. This review is an attempt to define the phenotypic and genotypic modulatory effects of estrogen on thyroid proliferative diseases. The significance and relevance of expression of estrogen receptors, α and β, in normal and malignant thyroid tissues and their effects on different molecular pathways involved in growth and function of the thyroid gland are discussed. These novel findings open up areas of developing alternative therapeutic treatments and preventive approaches which employ the use of antiestrogen to treat thyroid malignancies.

Analysis of multiplex endogenous estrogen metabolites in human urine using ultra-fast liquid chromatography-tandem mass spectrometry: a case study for breast cancer

A rapid, sensitive, specific and accurate analytical method of ultra-fast liquid chromatography combined with tandem mass spectrometry (UFLC-MS/MS) was established for simultaneous quantitative analysis of 16 distinct endogenous estrogens and their metabolites (EMs) in postmenopausal female urine. The quantitative method utilized a hydrolysis/extraction/derivatization step and a UFLC system to achieve separation in 16 min. The lower limit of quantitation for each estrogen metabolite was 2 pg mL(-1) with the percent recovery of a known added amount of estrogen at 93.2-109.3%. The intra-batch accuracy and precision for all analytes were 87.5-107.7% and 0.6-11.7%, respectively, while inter-batch accuracy and precision were 87.0-105.8% and 1.2-10.2%, respectively. Using this developed and validated method, the comprehensive metabolic profiling of 16 EMs in urine samples of 86 postmenopausal female breast cancer patients and 36 healthy controls was investigated by systematic statistical analysis. As a result, the circulating levels of 6 EMs were found to be different by a comparison of patients and healthy controls. The parent estrogens, estrone (E1) and 17β-estradiol (E2), as well as 2-hydroxyestradiol (2-OHE2) and 4-hydroxyestradiol (4-OHE2) were produced in higher abundance, whereas 16α-hydroxyestrone (16α-OHE1) and 2-methoxyestradiol (2-MeOE2) were decreased in the breast cancer group. 2-OHE2 and 4-OHE2 in particular showed significant elevation in patients, which are consistent with the carcinogenic mechanism hypothesis that catechol estrogens can react with DNA via quinones, resulting in mutations to induce breast cancer. Thus, 2,4-hydroxylation may be the dominant metabolic pathway for parent estrogens rather than 16α-hydroxylation. The lower level of 2-MeOE2 in the breast cancer group was believed to correlate with its protective effect against tumor formation. This study could provide valuable information on the association of the EM metabolic pathway with carcinogenesis as well as identify potential biomarkers for estrogen-induced breast cancer risk.

Interplay between insulin resistance and estrogen deficiency as co- activators in carcinogenesis

Both insulin resistance and estrogen deficiency result in complex metabolic disorder based mainly on defective cellular glucose uptake and on an atherogenic serum lipid profile. These alterations may be regarded as high risks for several life-threatening human diseases, such as type-2 diabetes, cardiovascular lesions and malignancies. Insulin resistance and estrogen deficiency are concomitant disorders with mutual interrelationship. Insulin resistance and the compensatory hyperinsulinemia provoke increased androgen synthesis at the expense of decreased estrogen production. Similarly, a moderate or severe decrease in serum estrogen levels enhances the prevalence of insulin resistant states both in men and women. Healthy premenopausal women enjoy the defensive effect of estrogens against metabolic and hormonal disorders. However, even a slight decrease in their circulatory estrogen levels associated with insulin resistance may increase the risk for cancers, particularly in the organs having high estrogen demand (breast, endometrium and ovary). On the other hand, postmenopausal state with profound estrogen deficiency confers high risk for cancers in different organs with either high or moderate estrogen demand. After menopause, hormone replacement therapy improves insulin sensitivity and decreases the enhanced inclination to malignancies in postmenopausal women. Recognition of the thorough interplay between insulin resistance and estrogen deficiency may illuminate many apparently controversial experimental and clinical findings concerning cancer development and therapeutic possibilities. Moreover, their interactions in the initiation and progression of human malignancies may supply new strategies in primary cancer prevention and cancer cure.

Towards non-surgical therapy for uterine fibroids: catechol-O-methyl transferase inhibitor shrinks uterine fibroid lesions in the Eker rat model

BACKGROUND

Uterine leiomyomas (fibroids) are the most common pelvic tumors in women. We assessed the potential therapeutic utility of Ro 41-0960, a synthetic catechol-O-methyl transferase inhibitor (COMTI), in the Eker rat.

METHODS

We randomized uterine fibroid-bearing Eker rats for treatment with Ro 41-0960 (150 mg/kg/12 h) versus vehicle for 2 and 4 weeks. The fibroids were measured by caliper and subjected to histological evaluation. Urinary levels of 2-hydroxy estrogen (E(2)), 16-hydroxy E2 and DPD (osteoporosis marker) and serum liver enzymes were evaluated. Expressions of Cyclin D1, proliferating cell nuclear antigen (PCNA), Poly [ADP-ribose] polymerase1 (PARP1), tumor suppressor gene (P53) and transforming growth factor (TGFβ3) were assessed in fibroids using immunohistochemical analysis or RT-PCR. Apoptosis was confirmed using terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL).

RESULTS

Ro 41-0960-treated rats exhibited fibroid volumes of 86 ± 7% and 105 ± 12% of initial burden, at 2 and 4 weeks post-treatment, respectively, significantly lower than control group (240 ± 15% and 300 ± 18%; P< 0.01). Ro 41-0960 increased the urinary 2-hydroxy E2/16-hydroxy E(2) ratio, level of p53 mRNA and TUNEL positivity (P< 0.05) and decreased PARP1, PCNA and cyclin D1 proteins and TGFβ3 mRNA (P< 0.05). Ro 41-0960 did not change normal tissue histology, liver functions or urinary DPD level.

CONCLUSIONS

Ro 41-0960 (COMTI) arrested growth/shrunk uterine fibroids in Eker rats. This result may be related to modulation of estrogen-dependent genes involved in apoptosis, proliferation and extracellular matrix deposition via accumulation of 2-hydroxy estrogen. The efficacy and safety of Ro 41-0960 in rats suggest its candidacy for treatment of uterine fibroids.

3,3'-diindolylmethane modulates estrogen metabolism in patients with thyroid proliferative disease: a pilot study

BACKGROUND

The incidence of thyroid cancer is four to five times higher in women than in men, suggesting a role for estrogen (E₂) in the pathogenesis of thyroid proliferative disease (TPD) that comprises cancer and goiter. The objective of this study was to investigate the antiestrogenic activity of 3,3'-diindolylmethane (DIM), a bioactive compound derived from cruciferous vegetables, in patients with TPD.

METHODS

In this limited phase I clinical trial study, patients found to have TPD were administered 300 mg of DIM per day for 14 days. Patients subsequently underwent a total or partial thyroidectomy, and tissue, urine, and serum samples were collected. Pre- and post-DIM serum and urine samples were analyzed for DIM levels as well as estrogen metabolites. DIM levels were also determined in thyroid tissue samples.

RESULTS

DIM was detectable in thyroid tissue, serum, and urine of patients after 14 days of supplementation. Urine analyses revealed that DIM modulated estrogen metabolism in patients with TPD. There was an increase in the ratio of 2-hydroxyestrones (C-2) to 16α-hydroxyestrone (C-16), consistent with antiestrogenic activity that results in more of C-2 product compared with C-16.

CONCLUSION

Our data suggest that DIM enhances estrogen metabolism in TPD patients and can potentially serve as an antiestrogenic dietary supplement to help reduce the risk of developing TPD. The fact that DIM is detected in thyroid tissue implicates that it can manifest its antiestrogenic activity in situ to modulate TPD.

Estrogen metabolite ratio: Is the 2-hydroxyestrone to 16α-hydroxyestrone ratio predictive for breast cancer?

Experimental studies have shown that two main estrogen metabolites hydroxylated by CYP1A1 and CYP1B1 in the breast differentially affect breast cell proliferation and carcinogenesis. Although 16α-hydroxyestrone (16αOHE1) exerts estrogenic activity through covalent estrogen receptor (ER) binding, 2-hydroxyestrone (2OHE1) presumably has antiestrogenic capabilities. The ratio of 2OHE1 to 16αOHE1 represents the relative dominance of one pathway over the other and is believed to be modifiable by diet. It was hypothesized that women with or at high risk of breast cancer have a lower estrogen metabolite ratio (EMR) compared with women without breast cancer. We conducted a systematic review on the EMR as a predictor for breast cancer. A total of nine studies (six prospective and three retrospective) matched our inclusion criteria, comprising 682 premenopausal cases (1027 controls) and 1189 postmenopausal cases (1888 controls). For the highest compared with the lowest quantile of urinary EMR, nonsignificant associations suggested at best a weak protective effect in premenopausal but not in postmenopausal breast cancer (range of odds ratios: 0.50-0.75 for premenopausal and 0.71-1.31 for postmenopausal). Circulating serum/plasma EMR was not associated with breast cancer risk. Associations were inconclusive for receptor subtypes of breast cancer. Uncontrolled factors known to be involved in breast carcinogenesis, such as 4-hydroxyestrone (4OHE1) concentration, may have confounded results for EMR. Results of the prospective studies do not support the hypothesis that EMR can be used as a predictive marker for breast cancer risk. Future research should concentrate on profiles of estrogen metabolites, including 4OHE1, to gain a more complete picture of the relative importance of single metabolites for breast cancer.

Is equol production beneficial to health?

The health benefits associated with soya food consumption have been widely studied, with soya isoflavones and soya protein implicated in the protection of CVD, osteoporosis and cancers such as those of the breast and prostate. Equol (7-hydroxy-3-(4'-hydroxyphenyl)-chroman), a metabolite of the soya isoflavone daidzein, is produced via the formation of the intermediate dihydrodaidzein, by human intestinal bacteria, with only approximately 30-40% of the adult population having the ability to perform this transformation following a soya challenge. Inter-individual variation in conversion of daidzein to equol has been attributed, in part, to differences in the diet and in gut microflora composition, although the specific bacteria responsible for the colonic biotransformation of daidzein to equol are yet to be identified. Equol is a unique compound in that it can exert oestrogenic effects, but is also a potent antagonist of dihydrotestosterone in vivo. Furthermore, in vitro studies suggest that equol is more biologically active than its parent compound, daidzein, with a higher affinity for the oestrogen receptor and a more potent antioxidant activity. Although some observational and intervention studies suggest that the ability to produce equol is associated with reduced risk of breast and prostate cancer, CVD, improved bone health and reduced incidence of hot flushes, others have reported null or adverse effects. Studies to date have been limited and well-designed studies that are sufficiently powered to investigate the relationship between equol production and disease risk are warranted before the clinical relevance of the equol phenotype can be fully elucidated.

Epistatic interactions between loci of one-carbon metabolism modulate susceptibility to breast cancer

In view of growing body of evidence substantiating the role of aberrations in one-carbon metabolism in the pathophysiology of breast cancer and lack of studies on gene-gene interactions, we investigated the role of dietary micronutrients and eight functional polymorphisms of one-carbon metabolism in modulating the breast cancer risk in 244 case-control pairs of Indian women and explored possible gene-gene interactions using Multifactor dimensionality reduction analysis (MDR). Dietary micronutrient status was assessed using the validated Food Frequency Questionnaire. Genotyping was done for glutamate carboxypeptidase II (GCPII) C1561T, reduced folate carrier (RFC)1 G80A, cytosolic serine hydroxymethyltransferase (cSHMT) C1420T, thymidylate synthase (TYMS) 5'-UTR tandem repeat, TYMS 3'-UTR ins6/del6, methylenetetrahydrofolate reductase (MTHFR) C677T, methyltetrahydrofolate-homocysteine methyltransferase (MTR) A2756G, methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR) A66G polymorphisms by using the PCR-RFLP/AFLP methods. Low dietary folate intake (P < 0.001), RFC1 G80A (OR: 1.38, 95% CI 1.06-1.81) and MTHFR C677T (OR: 1.74 (1.11-2.73) were independently associated with the breast cancer risk whereas cSHMT C1420T conferred protection (OR: 0.72, 95% CI 0.55-0.94). MDR analysis demonstrated a significant tri-variate interaction among RFC1 80, MTHFR 677 and TYMS 5'-UTR loci (P (trend) < 0.02) with high-risk genotype combination showing inflated risk for breast cancer (OR 4.65, 95% CI 1.77-12.24). To conclude, dietary as well as genetic factors were found to influence susceptibility to breast cancer. Further, the current study highlighted the importance of multi-loci analyses over the single-locus analysis towards establishing the epistatic interactions between loci of one-carbon metabolism modulate susceptibility to the breast cancer.

Urinary 2/16 estrogen metabolite ratio levels in healthy women: a review of the literature

This is a summary of the published literature on the urinary 2/16 estrogen metabolite ratio in human populations, and a report the observed range of normal values in healthy women. Original research studies that included the measurement of urinary estrogen metabolites in human subjects were identified through an extensive Medline search; 43 distinct studies were identified, including a total of 6802 healthy women. The range of mean values of the 2/16 ratio measured with the ELISA method varied from 0.98 to 1.74; in studies of pre-menopausal women the range of mean values was 1.5-2.74, in studies of post-menopausal women mean values ranged from 1.15 to 2.25. The heterogeneity across studies was highly significant (p-value Q-test: <0.0001). In multivariable analyses, only race confirmed its role as an independent predictor of 2/16 ratio (F-value: 7.95; p-value: 0.009), after adjustment for age and menopausal status. There appears to be a large body of data on the 2/16 urinary ratio in healthy women. However, summary estimates are difficult to perform due to the high variability of the published study-specific values. The data suggests that race may be a contributor to 2/16 urinary ratio levels.

Comparison of estrogens and estrogen metabolites in human breast tissue and urine

BACKGROUND

An important aspect of the link between estrogen and breast cancer is whether urinary estrogen levels are representative of the intra-tissue levels of bioavailable estrogens.

METHODS

This study compares 15 estrogen and estrogen metabolite levels in breast tissue and urine of 9 women with primary breast cancer using a quantitative liquid chromatography-mass spectrometry method.

RESULTS

The average levels of estrogens (estrone, 17 beta-estradiol) were significantly higher in breast tissue than in urine. Both the 2 and the 16-hydroxylation pathways were less represented in breast tissue than urine; no components of the 4-hydroxypathway were detected in breast tissue, while 4-hydroxyestrone was measured in urine. However, the 2/16 ratio was similar in urine and breast tissue. Women carrying the variant CYP1B1 genotype (Leu/Val and Val/Val) showed significantly lower overall estrogen metabolite, estrogen, and 16-hydroxylation pathway levels in breast tissue in comparison to women carrying the wild type genotype. No effect of the CYP1B1 polymorphism was observed in urinary metabolites.

CONCLUSIONS

The urinary 2/16 ratio seems a good approximation of the ratio observed in breast tissue. Metabolic genes may have an important role in the estrogen metabolism locally in tissues where the gene is expressed, a role that is not readily observable when urinary measurements are performed.

Comparison of liquid chromatography-tandem mass spectrometry, RIA, and ELISA methods for measurement of urinary estrogens

Absolute and relative concentrations of estrogens and estrogen metabolites are important for clinical decisions as well as for epidemiologic, experimental, and clinical research on hormonal carcinogenesis. RIA and ELISA are routinely used for measuring estrogen metabolites in blood and urine due to efficiency and low cost. Here, we compare absolute and ranked concentrations of estrone, estradiol, and estriol measured by indirect RIA and of 2-hydroxyestrone and 16alpha-hydroxyestrone measured by ELISA to the concentrations obtained using a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, which measures 15 estrogen metabolites concurrently. We used overnight urine samples collected from control women (362 premenopausal and 168 postmenopausal) participating in a population-based case-control study of breast cancer among Asian American women ages 20 to 55 years. When comparing RIA or ELISA levels to LC-MS/MS, absolute concentrations for the five estrogen metabolites ranged from 1.6 to 2.9 and 1.4 to 11.8 times higher in premenopausal and postmenopausal women, respectively (all P < 0.0001). However, LC-MS/MS measurements were highly correlated [Spearman r (r(s)) = 0.8-0.9] with RIA and ELISA measurements in premenopausal women and moderately correlated (r(s) = 0.4-0.8) in postmenopausal women. Measurements of the 2-hydroxyestrone:16alpha-hydroxyestrone ratio, a putative biomarker of breast cancer risk, were moderately correlated in premenopausal women (r(s) = 0.6-0.7) but only weakly correlated in postmenopausal women (r(s) = 0.2). LC-MS/MS had higher intraclass correlation coefficients (> or =99.6%) and lower coefficients of variation (< or =9.4%) than ELISA (> or =97.2% and < or =14.2%) and RIA (> or =95.2% and < or =17.8%). Comparison with the LC-MS/MS method suggests that the widely used RIA and ELISA estrogen metabolite measures may be problematic, especially at low estrogen metabolite levels characteristic of postmenopausal women.

Are estradiol metabolites involved in gynaecological carcinogenesis?

Certain estradiol metabolites are biologically active, sometimes several times more potent than their parent substance. Highly sophisticated laboratory methods allow us to understand oestrogenic effects as a net effect of the corresponding metabolite pattern. Currently, research is focused on the anticancerogenic effects of 2-hydroxyestrone and particularly 2-methoxyestradiol, as well as the possible carcinogenic properties of 4-hydroxyoestrogens and 16α-hydroxyestrone. The clinical relevance of these activities, demonstrated in in-vitro and animal experiments, remains unclear - it is proven, however, that the metabolite production can be altered in certain malignancies such as endometrial-, breast- and cervical carcinoma. Clinical studies, including our studies, have demonstrated a negative correlation between the ratio of 2-hydroxyestrone to 16α-hydroxyestrone and breast cancer risk. However, the design and interpretation of such studies should consider factors influencing metabolic pattern such as diet, physical activity, smoking, as well as internal diseases and certain drugs.

Reproducibility of fifteen urinary estrogens and estrogen metabolites over a 2- to 3-year period in premenopausal women

Endogenous estrogens play an integral role in the etiology of breast, endometrial, and, possibly, ovarian cancers. Estrogen metabolism yields products that are potentially both estrogenic and genotoxic, yet individual metabolic patterns are just beginning to be explored in epidemiologic studies. Within the Nurses' Health Study II, we examined reproducibility of 15 urinary estrogens and estrogen metabolites (EM) among 110 premenopausal women with three luteal-phase urine samples collected over 3 years. EM were measured by a recently developed high-performance liquid chromatography-tandem mass spectrometry (LC-MS(2)) method with high sensitivity, specificity, and precision. We assessed Spearman correlations and intraclass correlation coefficients (ICC) across the three samples. Correlations between urinary estrone or estradiol and EM were only modest (r = 0.1-0.5). The 2- and 4-hydroxylation pathways were highly correlated (r = 0.9) but weakly inversely correlated with the 16-hydroxylation pathway (r = -0.2). Within-woman reproducibility over time was fairly high for the three pathways, with ICCs ranging from 0.52 (16-hydroxylation pathway) to 0.72 (2-hydroxylation pathway). ICCs were similarly high for 2-catechols and the individual catechols (ICCs = 0.58-0.72). Individual and grouped methylated 2-catechols had fairly high ICCs (0.51-0.62), but methylated 4-catechols had low ICCs (0.14-0.27). These data indicate that, in general, urinary EM levels vary substantially among individuals compared with intraindividual variability. Within-person reproducibility over time for most EM measures is comparable to or better than that for well-vetted biomarkers such as plasma cholesterol and, in postmenopausal women, estradiol.

Ethnicity, body size, and estrogen levels in postmenopausal Hispanic and non-Hispanic white women

BACKGROUND

Hispanic women are at lower risk for incident breast cancer, but the reasons for this lower risk are unknown. Among postmenopausal women, breast cancer risk is inversely associated with circulating levels of 2-hydroxyestrone but directly associated with levels of 16alpha-hydroxyestrone, according to most studies. Likewise, according to most research, the ratio of 2-hydroxyestrone/16alpha-hydroxyestrone is, therefore, inversely associated with breast cancer risk.

METHODS

We measured levels of these two circulating estrones as well as estradiol in 40 Hispanic women and 40 non-Hispanic white women who were all postmenopausal and not taking hormones.

RESULTS

Compared with non-Hispanic white women, Hispanic women had 69% higher circulating levels of 2-hydroxyestrone (p = 0.04), and 10% lower levels of 16alpha-hydroxyestrone (p = 0.09). Consequentially, Hispanic women had more favorable estrogen profiles than non-Hispanic white women, with an 89% higher 2:16 ratio (p = 0.01). This finding was not substantially affected by adjustment for other breast cancer risk factors, including matching on body mass index (BMI).

CONCLUSIONS

This ethnic difference in estrogen profile requires further research to establish whether there is a causal relationship to breast cancer risk that may, at least partially, explain why postmenopausal Hispanic women have a lower incidence of breast cancer.

Urinary estrogen metabolites in women at high risk for breast cancer

OBJECTIVE

This study explored whether average urinary estrogen metabolites in breast cancer high-risk women can be used to identify a subgroup of women at particularly high risk to develop breast cancer, to which prevention strategies should be addressed.

METHODS

The population consisted of 77 high-risk women, 30 breast cancer patients and 41 controls. All subjects answered a standardized questionnaire; height and weight and spot urine samples were also obtained. Urine hydroxyestrogen metabolites were measured in triplicate by enzyme immunoassay, and the estrogen metabolite ratios for each individual were calculated.

RESULTS

The 2:16 OHE ratio (2-hydroxyestrone/16-alpha-hydroxyestrone) in women at high risk for breast cancer was similar to that observed in the breast cancer group (1.76 +/- 2.33 versus 1.29 +/- 0.80) and lower than in controls (2.47 +/- 1.14; P = 0.00). At the multivariate linear regression model, the 2:16 OHE ratio was significantly associated with diagnosis (P = 0.000 for both the high risk and breast cancer group versus the controls) and body mass index (P = 0.005), but not with age (P = 0.604), or smoking history (P = 0.478).

CONCLUSIONS

This study suggests that lower urinary 2:16 OHE ratios are predictors of breast cancer risk. Profiling estrogen metabolites may identify women who are more probably to develop breast cancer within a population of women with known risk factors and may help to further elucidate the clinical relevance of urinary 2:16 OHE ratios as clinical markers and prognostic indicators in this population.

Circulating 2-hydroxy- and 16alpha-hydroxy estrone levels and risk of breast cancer among postmenopausal women

Circulating estrogens are associated with breast cancer risk in postmenopausal women. Given that estrogen metabolites are potentially both mitogenic and genotoxic, it is possible that plasma levels of estrogen metabolites are related to breast cancer risk. We conducted a prospective, nested case-control study within the Nurses' Health Study. Blood samples, collected in 1989 to 1990, were assayed for 2-OH and 16alpha-OH estrone among 340 cases and 677 matched controls not taking postmenopausal hormones. Multivariate relative risks (RR) and 95% confidence intervals (95% CI) were calculated by conditional logistic regression, adjusting for breast cancer risk factors. Neither 2-OH nor 16alpha-OH estrone concentrations were significantly associated with breast cancer risk overall (top versus bottom quartile: RR, 1.19; 95% CI, 0.80-1.79; P(trend) = 0.40 for 2-OH estrone and RR, 1.04; 95% CI, 0.71-1.53; P(trend) = 0.81 for 16alpha-OH estrone). The ratio between the two metabolites (2-OH:16alpha-OH estrone) was similarly unrelated to risk overall (1.30; 95% CI, 0.87-1.95; P(trend) = 0.35). Although no associations were detected among women with estrogen receptor (ER)-positive/progesterone receptor (PR)-positive tumors, significant positive associations were observed for 2-OH estrone and the 2-OH:16alpha-OH estrone ratio among women with ER-negative/PR-negative tumors (RR, 3.65; 95% CI, 1.23-10.81; P(trend) = 0.01; P(heterogeneity) = 0.02 for 2-OH estrone; RR, 3.70; 95% CI, 1.24-11.09; P(trend) = 0.004; P(heterogeneity) = 0.005 for 2-OH:16alpha-OH estrone). These data do not support the hypothesized inverse associations with 2-OH estrone and the 2-OH:16alpha-OH estrone ratio or the hypothesized positive association with 16alpha-OH estrone. The significant positive associations with 2-OH estrone and the 2-OH:16-OH estrone ratio among women with ER-negative/PR-negative tumors needs to be replicated in future studies.

Coffee consumption and CYP1A2*1F genotype modify age at breast cancer diagnosis and estrogen receptor status

CYP1A2 plays a key role in the metabolism of both estrogen and coffee. Women with higher coffee intake and the CYP1A2*1F A/A genotype have a ratio of high 2-hydroxyestrone (2-OHE1) to 16alpha-OHE1. 2-OHE1 is a weak estrogen and may even block the estrogen receptor (ER), whereas 16alpha-OHE1 is procarcinogenic. We hypothesized that moderate to high coffee consumption (> or =2 cups per day) combined with the CYP1A2*1F A/A genotype would be associated with a later age at diagnosis and a greater proportion of ER-negative (ER-) tumors among patients with breast cancer. We genotyped 458 patients with breast cancer (age, 25-99 years) in Lund, Sweden, for CYP1A2*1F. Information on lifestyle factors and tumor characteristics were obtained from preoperative questionnaires and pathology reports. Among patients with CYP1A2*1F A/A (51.3%), moderate to high consumption was associated with a later age at diagnosis compared with low coffee consumption (59.8 versus 52.6 years, P = 0.0004). These patients were also more likely to have ER- tumors than patients with low consumption (14.7% versus 0%, P = 0.018). Coffee was not associated with ER status or age at diagnosis in patients with at least one C allele. Age at diagnosis was not associated with ER status in patients with CYP1A2*1F A/A, but younger patients (<50 years) with at least one C allele were more likely to have ER- tumors compared with older patients (odds ratio, 4.2; 95% confidence interval, 1.9-9.3; P = 0.0002). These findings raise the hypothesis that coffee slows the growth of ER-positive tumors in patients with CYP1A2*1F A/A and may have implications for breast cancer if confirmed.

Soy protein isolate increases urinary estrogens and the ratio of 2:16alpha-hydroxyestrone in men at high risk of prostate cancer

Specific estrogen metabolites may initiate and promote hormone-related cancers. In epidemiological studies, significantly lower excretion of urinary estradiol (E2) and lower ratio of urinary 2-hydroxy estrogens to 16alpha-hydroxyestrone (2:16 OH-E1) have been reported in prostate cancer cases compared to controls. Although soy supplementation has been shown to increase the ratio 2:16 OH-E1 in women, no studies to our knowledge have investigated the effects of soy supplementation on estrogen metabolism in men. The objective of this randomized controlled trial was to determine the effects of soy protein isolate consumption on estrogen metabolism in men at high risk for developing advanced prostate cancer. Fifty-eight men supplemented their habitual diets with 1 of 3 protein isolates: 1) isoflavone-rich soy protein isolate (SPI+) (107 mg isoflavones/d); 2) alcohol-washed soy protein isolate (SPI-) (<6 mg isoflavones/d); or 3) milk protein isolate (MPI), each providing 40 g protein/d. At 0, 3, and 6 mo of supplementation, the urinary estrogen metabolite profile was measured by GC-MS. Both soy groups had higher E2 excretion than the MPI group at 3 and 6 mo. After 6 mo of supplementation, the SPI+ group had a significantly higher urinary 2:16 OH-E1 ratio than the MPI group. Increased urinary E2 excretion and 2:16 OH-E1 ratio in men consuming soy protein isolate are consistent with studies in postmenopausal women and suggest that soy consumption may be beneficial in men at high risk of progressing to advanced prostate cancer as a result of effects on endogenous estrogen metabolism.

Head and neck cancer: a case for inhibition by isothiocyanates and indoles from cruciferous vegetables

Chemical carcinogens derived from cigarettes and other tobacco products, as well as betel quid, paan, and alcohol consumption, are commonly associated with head and neck cancer risk. This is a particularly debilitating cancer, with a high recurrence rate and long-term treatment comorbidities affecting health and lifestyle. Controlling tobacco access or use may be an ideal prevention strategy but may also be challenging or undesired. Individuals, however, may be able to reduce their risk through simple and focused dietary change. Results from epidemiologic studies, basic research, and clinical investigations suggest that a diet rich in cruciferous vegetables may increase carcinogen metabolism, induce apoptosis, and reduce the risk of developing a primary head and neck tumor. This review briefly summarizes head and neck cancer nutritional epidemiology, and then describes the biochemical and epidemiologic literature describing the effects of crucifer consumption on head and neck carcinogenesis. To translate these findings, the strengths and limitations of specific intervention models are discussed, including differences in target populations and the choice of a food-based or pill-based approach for intervention. Addressing these factors in a future intervention may define a low-cost and non-toxic approach to reduce the burden of head and neck cancer.

Effect of Energy Deficiency on Estrogen Metabolism in Premenopausal Women

PURPOSE

Physical activity has been associated with decreased breast cancer risk, potentially through changes in estrogen metabolism. Two-hydroxyestrone (2-OHE1) and 16alpha-hydroxyestrone (16alpha-OHE1) have different biological properties, and the ratio of these metabolites (2/16) has been proposed to predict breast cancer risk. Diet and exercise have been found to influence estrogen metabolism, particularly when a state of negative energy balance is achieved. We sought to determine whether 4 months of moderate-intensity exercise coupled with calorie restriction would result in changes in urinary 2-OHE1, 16alpha-OHE1, or 2/16 in sedentary, premenopausal, eumenorrheic women.

METHODS

Average age was 31.5 yr, average body fat was 31.6%, and average BMI was 23.7. Urinary estrogen metabolites were measured in 24 women during the baseline and for four intervention months in the midfollicular and midluteal phases.

RESULTS

The intervention produced a significant drop in body fat (4.5%) and body weight (3.7 kg). Aerobic fitness increased significantly (26%; P < 0.001). Overall, there were no significant effects of the diet and exercise intervention on 2-OHE1, 16alpha-OHE1, or 2/16. However, when divided into tertiles according to baseline 2/16, the intervention resulted in significant increases in 2/16 in women in the lowest tertile. Women in the lowest tertile (average 2/16 = 0.91) did not differ from the other tertiles in baseline estradiol concentrations, body fat, weight, fitness, or changes in these variables with the intervention.

CONCLUSION

The data suggest that women at higher risk for developing breast cancer because of low 2/16 may reduce their risk by participating in lifestyle interventions such as exercise/calorie restriction.