Breast Adipose Tissue Research Articles

Comparison of Breast and Abdominal Adipose Tissue Mesenchymal Stromal/Stem Cells in Support of Proliferation of Breast Cancer Cells

In this study, we compared MSCs from breast and abdominal tissue in terms of their expression of genes deemed important in the support of breast cancer growth and their effect on gene profile of macrophages after coculture. In addition, we investigated the role of MSCs, alone or in combination with macrophages, on proliferation of breast cancer cell lines. Our results show that MSCs derived from breast and abdominal adipose tissues have a comparable gene expression profile, have similar effect on gene expression of macrophages, and are comparable in supporting breast cancer cell line proliferation.

Acoustic radiation force impulse imaging with Virtual Touch™ tissue quantification: mean shear wave velocity of malignant and benign breast masses

Acoustic radiation force impulse imaging (ARFI) with Virtual Touch™ tissue quantification (VTTQ) enables the determination of shear wave velocity (SWV) in meters per second (m/s). The aim of our study was to describe the mean SWV in normal breast tissue and various breast masses. We performed measurements of SWV with ARFI VTTQ in 145 breast masses (57 malignant, 88 benign) and in the adjacent breast parenchyma and adipose tissue. The mean SWV as well as the rate of successful measurements were analyzed. The difference between adipose tissue and parenchyma was statistically significant (3.05 versus 3.65 m/s) (P < 0.001). Focusing on breast masses, numerous measurements exceeded the upper limit of possible measurement (≥9.10 m/s, indicated as “X.XX m/s”). Nevertheless, the difference between the malignant and benign masses was statistically significant (8.38 ± 1.99 m/s versus 5.39 ± 2.95 m/s) (P < 0.001). The best diagnostic accuracy (75.9%) was achieved when the cutoff point for malignancy was set to 9.10 m/s in ARFI VTTQ. This implies that the SWV was regarded as suspicious when the upper limit of possible measurement was exceeded and the machine returned the value X.XX m/s. In conclusion, ARFI VTTQ is a feasible method for measurement of SWV in a region of interest. Furthermore, we propose the event of a highly elevated SWV as a significant criterion for malignancy. However, the method is technically not yet fully developed, and the problem of unsuccessful measurements must still be solved.

Biochemical and molecular mechanisms for the association between obesity, chronic Inflammation, and breast cancer

Upper body obesity is a risk factor for postmenopausal breast cancer and is related to an aggressive tumor phenotype and a poor prognosis regardless of menopausal status. After the menopause, the major mechanism for the association with disease risk is elevated estrogen production by adipose tissue, due to a high level of aromatase activity: these hormone-dependent tumors express both estrogen and progesterone receptors. Other important biological factors of risk include leptin and adiponectin, adipokines with opposing endocrine and paracrine activities, and obesity-related hyperinsulinemia. Chronic inflammation of the breast adipose tissue, which occurs in some obese women and is indicated by the accumulation of macrophages around dead adipocytes ("crown-like structures"), rather than adiposity per se, may prove to be the pathological lesion responsible for both local aromatase induction, and enhanced invasiveness and metastatic capacity through biological mechanisms that involve leptin, tumor necrosis factor-α, and insulin. A causal association between obesity in premenopausal women and breast cell epithelial-mesenchymal transition, perhaps with the participation of the Wnt signaling pathway, and aggressive hormone-independent breast cancer is suggested by a number of experimental and clinical studies.

Diagnostic value of sonographic changes of adipose tissue in benign and malignant breast lesions

Objective To investigate the diagnostic value of sonographic changes of adipose tissue in benign and malignant breast lesions.Methods The sonographic characteristics of subcutaneous adipose tissue were retrospectively analyzed in 92 patients with 114 breast lesions,all lesions were confirmed by postoperative pathology.Receive operating characteristic (ROC) curve was drew with the pathological results as standard,the diagnostic value of subcutaneous adipose tissue changes in benign and malignant breast lesions was evaluated.Results The area under the ROC curve that derived from all of the lesions (61 benign and 53 malignant) was 0.862 (P =0.000).The ultrasonographic findings which showed subcutaneous adipose tissue changes at grade Ⅲ or higher suggested that the tumors were more likely malignant lesions.When adipose tissue changes at grade Ⅲ was taken as the diagnostic indicator for the presence of malignant breast lesions,the diagnostic sensitivity reached 73.6％ while specificity reached 93.4％.At ultrasound imaging scan,the adipose tissue in malignant lesions had the following manifestations:increased fibrosis,increased echogenicity,the sonographic images were turbidity or blurred,presence of ground-glass-like opacity.There were significant differences (P =0.000) between the benign and the malignant lesions in the range of adipose tissue changes.Conclusions The ultrasonographic changes were helpful to the differential diagnosis between the benign and the malignant breast lesions. Key words: Ultrasonography; Breast neoplasms; Diagnosis,differential

Association between sex hormones, glucose homeostasis, adipokines, and inflammatory markers and mammographic density among postmenopausal women

The biological mechanisms underlying the relationship between mammographic density and breast cancer risk are unknown. Our objective was to examine the association between mammographic density and circulating factors that are putative breast cancer intermediate endpoints. Biologic data from a year-long aerobic exercise intervention trial conducted in 302 postmenopausal women aged 50-74 years were analyzed. Sex hormones, markers of glucose homeostasis, inflammatory markers, and adipokines were assayed in fasting blood drawn at baseline and after 1 year. Area and volumetric measurements of mammographic dense fibroglandular and nondense fatty tissue were made. Multiple linear regression was used to examine the association between the circulating factors and mammographic measures and partial correlations were estimated. Mammographic nondense volume was positively correlated with concentrations of estradiol (r = 0.28), estrone (r = 0.13), insulin (r = 0.41), glucose (r = 0.15), leptin (r = 0.49), and C-reactive protein (r = 0.22), and negatively correlated with sex hormone binding globulin (r = -0.30) and adiponectin (r = -0.12) but correlations became null after adjustment for overall body adiposity as represented by body mass index and waist circumference. With adjustment for overall adiposity, mammographic dense volume, a measure that represents fibroglandular tissue, was negatively correlated with leptin (r = -0.19) and C-reactive protein (r = -0.19). As expected, circulating factors originating from or correlated with adipose tissue were also correlated with mammographic measures of breast adipose tissue, but not after adjustment for overall body adiposity. Interpreting correlations between adiposity-derived factors and mammographic measures whose validity may be affected by adiposity is problematic. To rectify this problem, future studies with very good measures of the volume of fibroglandular tissue in the breast will be necessary.

Identification of Macrophage Extracellular Trap-Like Structures in Mammary Gland Adipose Tissue: A Preliminary Study

PAD4-mediated hypercitrullination of histone H4 arginine 3 (H4R3) has been previously found to promote the formation of Neutrophil Extracellular Traps in inflamed tissues and the resulting histone H4 citrulline 3 (H4Cit3) modification is thought to play a key role in extracellular trap (ET) formation by promoting chromatin decondensation. In addition to neutrophils, macrophages have also recently been found to generate functional extracellular traps (METs). However, a role for PADs in ET formation in macrophages has not been previously described. Transcripts for PAD2 and PAD4 are found in mature macrophages and these cells can be induced to citrullinate proteins, thus raising the possibility that PADs may play a direct role in ET formation in macrophages via histone hypercitrullination. In breast and visceral white adipose tissue from obese patients, infiltrating macrophages are often seen to surround dead adipocytes forming characteristic “crown-like structures” (CLS) and the presence of these lesions is associated with increased levels of inflammatory mediators. In light of these observations, we have initiated studies to test whether PADs are expressed in CLS macrophages and whether these macrophages might form METs. Our preliminary findings show that PAD2 (and to a lesser extent, PAD4) is expressed in both in the macrophage cell line (RAW 264.7) and in CLS lesions. Additionally, we provide evidence that macrophage-derived extracellular histones are seen around presumptive macrophages within CLS lesions and that these histones contain the H4Cit3 modification. These initial findings support our hypothesis that obesity-induced adipose tissue inflammation promotes the formation of METs within CLS lesions via PAD-mediated histone hypercitrullination. Subsequent studies are underway to further validate these findings and to investigate the role in PAD-mediated MET formation in CLS function in the mammary gland.

Abstract P4-13-09: The effect of weight change on breast adipose and dense tissue

Abstract Background Observational studies indicate that weight gain or loss alters breast cancer risk. Hormonal prevention with tamoxifen or ovarian suppression reduces mammographic breast density, but has no impact on breast adipose tissue.1 The aim of this study was to assess whether change in weight is associated with change in breast density, breast fat or both. Methods 74 premenopausal women aged between 35 and 45 years, with a family history of breast cancer, were recruited from our Family History Clinic. 36 were allocated to a 25% calorie-restricted Mediterranean diet and exercise intervention; a further 38 women were separately recruited into a control group and given written diet and exercise advice only. At baseline and 12 months breast dense and non-dense (largely adipose) components of the breast were measured: area using Cumulus2 and volume using the Manchester ‘stepwedge’ method.3 Visual assessment of percentage density was reported to the nearest 5%.4 We used correlations to relate percentage change in absolute dense and non-dense (area and volume) to percentage change in: weight, total body fat (DXA), intra-abdominal and subcutaneous abdominal fat (MRI), as well as serum total IGF-I. Results At 12 months, 40 (54%) women lost &amp;gt;1.5% body weight, 14 (19%) gained &amp;gt;1.5% and 21 (28%) remained weight stable, &amp;lt;+/−1.5% weight change. There was a range of percentage weight change from −16.3% to +9.8%. There were no significant changes in dense area (r = −0.14 p = 0.29) or volume (r = −0.01 p = 0.97) with weight change. However, both the area and volume of non-dense breast tissue changed significantly in relation to change in body weight (r = 0.52 p &amp;lt; 0.0001 &amp; r = 0.78 p &amp;lt; 0.0001 respectively), total body fat (r = 0.49 p &amp;lt; 0.001 &amp; r = 0.75 p = &amp;lt;0.0001 respectively), intra-abdominal fat (r = 0.45 p &amp;lt; 0.0001 &amp; r = 0.36 p = 0.03 respectively) and subcutaneous abdominal fat (r = 0.55 p &amp;lt; 0.0001 &amp; r = 0.52 p = 0.002 respectively). Visually assessed percentage mammographic density was significantly inversely related to weight (r = −0.27 p = 0.038). Serum total IGF-I was not significantly correlated with breast dense area. (r = −0.21 and p = 0.09). Conclusions These data indicate that dense area and volume remain stable irrespective of change in weight. Non-dense area changes significantly in response to weight change in parallel with total and abdominal fat stores. These observations were performed on relatively small numbers of women and require confirmation in larger series. 1. Cuzick et al J Natl Cancer Inst. 103(9): 744–52, 2011. 2. Boyd NF et al J Natl Cancer Inst. 87(9) 670–675 1995. 3. Diffy et al IWIDM 2006, LNCS 4046 p1-9. In Astley et al (Eds) Springer-Verlag Berlin Heidelberg 2006 4. Brisson J et al. Cancer Epidemiol Biomarkers Prev 2003;12:7288–32. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-13-09.

Abstract P1-09-07: Topical 4-OHT trial in women with DCIS of the breast: report of plasma and breast tissue concentration of tamoxifen metabolites

Abstract Background: Earlier studies have shown that 1–2mg of 4-hydroxytamoxifen (4–OHT) gel applied to the breast skin reduced cell proliferation in estrogen receptor (ER) positive invasive cancers to a similar degree as oral tamoxifen (TAM), with significantly lower plasma levels. We now report results of a Phase IIB pre-surgical window trial of women with DCIS, designed to obtain pilot data in early lesions. Our ultimate goal is to develop transdermal 4-OHT as an alternative to oral TAM for women at high risk for breast cancer and those with DCIS. The study was closed early because the manufacturer discontinued the drug supply, but remains blinded until all biomarker analysis is complete. Here we report the plasma and breast adipose tissue concentration of TAM metabolites from the topical 4-OHT gel group (4 mg) in comparison with the oral TAM group (20mg). Methods: Women with DCIS were enrolled, and randomized to 4-OHT gel (4mg/day, 2mg per breast, E: Z isomers = 1:1,) or to oral (Z) TAM (20mg/day) for 4–10 weeks before surgery. Blood was collected on the day of surgery, and breast adipose tissue was collected at surgery. There were a total of 22 patients with matched blood and breast adipose tissue. The concentration of TAM metabolites in plasma and breast tissue was determined with liquid chromatography/tandem mass spectrometry. We assumed that the subjects with detectable N-desmethyl TAM (NDT) in plasma belong to the oral TAM group because NDT is not a product of 4-OHT metabolism. Under this assumption, 13 subjects were categorized into oral TAM group, and 9 subjects into the topical 4-OHT group. Wilcoxon rank-sum test was used for statistical analysis. Results: The results are shown in the table. The concentration is presented as mean ± SD; the lowest quantitation limit (LQL) was 1 ng/mL for plasma, and 3 ng/g for tissue. TAM and its metabolites were found in the plasma of the presumed oral TAM group, with high levels of TAM and NDT. In the presumed 4-OHT gel group, only (Z) 4-OHT was found in the plasma although both (E) and (Z) forms were applied. The mean plasma level of 4-OHT in the gel group was 70% lower than the mean of 4-OHT in the oral TAM group (p = 0.004). In breast tissue, similar amounts of (E) and (Z) forms of 4-OHT were found in the 4-OHT gel group, with the (Z) 4-OHT level being equivalent to that in the oral TAM group (p = 0.48). Endoxifen was only found in the oral TAM group. We saw no evidence of further metabolic transformation of 4-OHT in the breast following topical administration. Conclusions: With 4 mg of 4-OHT gel daily applied to the breasts of DCIS patients, the mean plasma level of 4-OHT was significantly lower and the mean breast tissue level of 4-OHT was similar to that in women taking oral TAM 20 mg daily, thus confirming the results from previous studies. We are still evaluating efficacy of topical 4-OHT in terms of reduction of cell proliferation (Ki67). Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-09-07.

Retinoids, Carotenoids, and Tocopherols in Breast Adipose Tissue and Serum of Benign Breast Disease and Breast Cancer Patients

Various retinoic acid (RA) isomers (all-trans, 13-cis, 11-cis, and 9-cis) as well as retinol, carotenoids, and tocopherol concentrations were determined in both serum and breast adipose tissue of 22 benign breast disease patients and 52 breast cancer patients categorized into 4 stages by malignancy. Serum RA isomers were analyzed by a newly developed sensitive method combining a high-performance liquid chromatography and a gas chromatography-mass spectrometry, and retinol, carotenoid, and tocopherol concentrations using a high-performance liquid chromatography system. The breast cancer patients showed significantly lower serum retinol, whereas significantly higher breast adipose tissue retinol concentration than those of benign breast disease patients. Although breast cancer patients showed significantly higher serum all-trans and 13-cis RA concentrations, 11-cis RA in breast adipose tissue was significantly lower in the breast cancer patients than those of benign breast disease patients and it was associated with the stage of malignancy. The current study indicates that the retinol and RA isomers in the target tissue of breast tumor patients are not reflecting their concentrations in circulation. The mechanisms of tissue specific uptake of RA isomers and their functions warrant further studies.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Accelerated Mammary Tumor Onset in a HER2/ Neu Mouse Model Exposed to DDT Metabolites Locally Delivered to the Mammary Gland

Background: The association of DDT (dichlorodiphenyltrichloroethane) with breast cancer is controversial, but animal studies directly linking DDT to risk are lacking. Concerns with DDT reside in its environmental persistence, bioaccumulation in breast adipose tissue, and endocrine-disrupting actions. Whereas most attention has been focused on estrogenic congeners, we tested the cancer-inducing potential of the antiandrogen, p,p´-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene], the most prevalent and persistent DDT metabolite.Objectives: We aimed to determine whether developmental exposure to p,p´-DDE stored in adipose tissue surrounding the cancer-prone mammary epithelium of MMTV-Neu mice influences tumor development.Methods: For localized delivery, Elvax 40P pellets containing p,p´-DDE were implanted into the mammary fat pads of prepubertal female mice. We compared mammary tumor development with p,p´-DDE with development in response to its estrogenic isomer, o,p´-DDE [1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl) ethylene], and a mixture of both isomers.Results: p,p´-DDE implants significantly accelerated mammary tumor onset compared with vehicle Elvax implants. o,p´-DDE had similar results, but only at ≤ 10 months of age. Lipid-adjusted levels of p,p´-DDE in mammary adipose tissue and serum in young mice were within the ranges of human exposure, whereas concentrations in aged mice were low to undetectable. Exposure to a 2:1 ratio of p,p´-DDE:o,p´-DDE did not result in the younger latency observed with the individual isomers.Conclusions: p,p´-DDE exposure at concentrations relevant to human exposure accelerates mammary carcinogenesis in mice, possibly through hormonal and/or other actions. These data suggest that DDE exposure would promote, but not cause, mammary tumorigenesis. Developmental exposure in immature mammary tissue continues to affect tumor onset even after p,p´-DDE levels have declined. Future studies are needed to determine whether early exposure to p,p´-DDE correspondingly predisposes women to early-onset breast cancer.

Mature breast adipocytes promote breast cancer cell motility

Adipocytes express substances involved in both normal physiology and pathological processes. One such adipocyte protein is the Serpin (serine protease inhibitor) plasminogen activator inhibitor-1 (PAI-1). PAI-1 functions to inhibit urokinase type plasminogen activator (uPA) though PAI-1 itself is also implicated in breast cancer progression. While the role of adipocytes in breast cancer development is not fully understood, obesity is a known risk factor associated with breast cancer. Thus, we characterized adipocytes from breast and omental tissues for PAI-1 and uPA, and the influence of adipocytes on breast cancer cell motility. Using preadipocyte cells from breast and omental adipose tissue, we differentiated each site into mature adipocytes. PAI-1 protein was found in breast adipocytes>omental preadipocytes>omental adipocytes>breast preadipocytes. Interestingly, uPA protein was not detected in any of these cell types. We then incubated breast adipocyte conditioned media (Adip-CM) and preadipocyte conditioned media (PreAdip-CM) on both normal (MCF-10A) and malignant (MCF-10CA1) breast epithelial cell lines. Adip-CM, but not PreAdip-CM, (a) increased cell motility in both MCF-10A and MCF-10CA1 cells; (b) increased cell-associated uPA activity in both cell lines; (c) increased phosphorylated-Akt levels in MCF-10CA1 cells; and (d) gene array profiles show altered expression of several genes associated with cancer adhesion, metastasis and signaling. Our results suggest that mature breast adipocytes are capable of altering the epithelial cell phenotype, producing a more motile cell type and further provide a potential link between obesity and risk of breast cancer.

Compton scattering spectrum as a source of information of normal and neoplastic breast tissues' composition

In this work we measured X-ray scatter spectra from normal and neoplastic breast tissues using photon energy of 17.44keV and a scattering angle of 90°, in order to study the shape (FWHM) of the Compton peaks. The obtained results for FWHM were discussed in terms of composition and histological characteristics of each tissue type. The statistical analysis shows that the distribution of FWHM of normal adipose breast tissue clearly differs from all other investigated tissues. Comparison between experimental values of FWHM and effective atomic number revealed a strong correlation between them, showing that the FWHM values can be used to provide information about elemental composition of the tissues.

Breast and Abdominal Adipose Multipotent Mesenchymal Stromal Cells and Stage-Specific Embryonic Antigen 4 Expression

We assessed human mesenchymal stem cells (MSCs) harvested from breast and abdominal adipose tissues enriched in embryonic stage-specific antigen (SSEA-4) expression for osteogenic and adipogenic differentiation in comparison to a mixed cell population. Human adipose was obtained from abdominal and breast tissues of females undergoing gastric bypass and breast reduction, respectively. SSEA-4-expressing cells were enriched from the mixed cell population by magnetic cell sorting and expanded in culture. The results showed that freshly isolated cells from breast and abdominal tissues based on adipose from 3 patients comprised 12 and 10% SSEA-4+ cells, respectively. At passage 0, 48% of the cells from breast adipose tissue were positive for SSEA-4 while 12% of the cells from abdominal adipose tissue were positive for this antigen. The level of SSEA-4-expressing cells remained relatively constant with passaging; SSEA-4-expressing cells from breast tissue comprised 45% of the total while 27% of the cells from abdominal adipose tissue expressed SSEA-4 at passage 5. Cells sorted for SSEA-4 expression exhibited a higher potential for differentiation toward osteogenic and adipogenc cell lineages in vitro when compared to a mixed population. Interestingly, SSEA-4 expression was lost upon differentiation, suggesting that the antigen marks a subpopulation of MSCs. Taken together, the data demonstrate that breast adipose tissue is highly enriched in a subpopulation of MSCs expressing SSEA-4 and suggest that SSEA-4 may be a marker of a subpopulation of MSCs with high potential for osteogenic and adipogenic differentiation.

Normal breast tissue of obese women is enriched for macrophage markers and macrophage-associated gene expression

Activation of inflammatory pathways is one plausible mechanism underlying the association between obesity and increased breast cancer risk. However, macrophage infiltration and local biomarkers of inflammation in breast adipose tissue have seldom been studied in association with obesity. Gene expression profiles of normal breast tissue from reduction mammoplasty patients were evaluated by whole genome microarrays to identify patterns associated with obesity status (normal-weight, body mass index (BMI) <25; overweight, BMI 25-29.9; obese, BMI ≥30). The presence of macrophage-enriched inflammatory loci with immunopositivity for CD68 protein was evaluated by immunohistochemistry (IHC). After adjusting for confounding by age, 760 genes were differentially expressed (203 up and 557 down; FDR=0.026) between normal-weight and obese women. Gene ontology analysis suggested significant enrichment for pathways involving IL-6, IL-8, CCR5 signaling in macrophages and RXRα and PPARα activation, consistent with a pro-inflammatory state and suggestive of macrophage infiltration. Gene set enrichment analysis also demonstrated that the genomic signatures of monocytes and macrophages were over-represented in the obese group with FDR of 0.08 and 0.13, respectively. Increased macrophage infiltration was confirmed by IHC, which showed that the breast adipose tissue of obese women had higher average macrophage counts (mean=8.96 vs. 3.56 in normal-weight women) and inflammatory foci counts (mean=4.91 vs. 2.67 in normal-weight women). Obesity is associated with local inflammation and macrophage infiltration in normal human breast adipose tissues. Given the role of macrophages in carcinogenesis, these findings have important implications for breast cancer etiology and progression.

Mammary adipocytes bioactivate 25‐hydroxyvitamin D3 and signal via vitamin D3 receptor, modulating mammary epithelial cell growth

The vitamin D(3) receptor (VDR) is present in all microenvironments of the breast, yet it is hypothesized to signal through the epithelium to regulate hormone induced growth and differentiation. However, the influence or contribution of the other microenvironments within the breast that express VDR, like the breast adipose tissue, are yet to be investigated. We hypothesized that the breast adipocytes express the signaling components necessary to participate in vitamin D(3) synthesis and signaling via VDR, modulating ductal epithelial cell growth and differentiation. We utilized human primary breast adipocytes and VDR wild type (WT) and knockout (KO) mice to address whether breast adipocytes participate in vitamin D(3) -induced growth regulation of the ductal epithelium. We report in this study that breast primary adipocytes express VDR, CYP27B1 (1α-hydroxylase, 1α-OHase), the enzyme that generates the biologically active VDR ligand, 1α,25-dihydroxyvitamin D(3) (1,25D(3) ), and CYP24 (24-hydroxylase, 24-OHase), a VDR-1,25D(3) induced target gene. Furthermore, the breast adipocytes participate in bioactivating 25-hydroxyvitamin D(3) (25D(3) ) to the active ligand, 1,25D(3) , and secreting it to the surrounding microenvironment. In support of this concept, we report that purified mammary ductal epithelial fragments (organoids) from VDR KO mice, co-cultured with WT breast adipocytes, were growth inhibited upon treatment with 25D(3) or 1,25D(3) compared to vehicle alone. Collectively, these results demonstrate that breast adipocytes bioactivate 25D(3) to 1,25D(3) , signal via VDR within the adipocytes, and release an inhibitory factor that regulates ductal epithelial cell growth, suggesting that breast adipose tissue contributes to vitamin D(3) -induced growth regulation of ductal epithelium.

Nondense mammographic area and risk of breast cancer

IntroductionThe mechanisms underlying the strong association between percentage dense area on a mammogram and the risk of breast cancer are unknown. We investigated separately the absolute dense area and the absolute nondense area on mammograms in relation to breast cancer risk.MethodsWe conducted a nested case-control study on prediagnostic mammographic density measurements and risk of breast cancer in the Nurses' Health Study and the Nurses' Health Study II. Premenopausal mammograms were available from 464 cases and 998 controls, and postmenopausal mammograms were available from 960 cases and 1,662 controls. We used a computer-assisted thresholding technique to measure mammographic density, and we used unconditional logistic regression to calculate OR and 95% CI data.ResultsHigher absolute dense area was associated with a greater risk of breast cancer among premenopausal women (ORtertile 3 vs 1 = 2.01, 95% CI = 1.45 to 2.77) and among postmenopausal women (ORquintile 5 vs 1 = 2.19, 95% CI = 1.65 to 2.89). However, increasing absolute nondense area was associated with a decreased risk of breast cancer among premenopausal women (ORtertile 3 vs 1 = 0.51, 95% CI = 0.36 to 0.72) and among postmenopausal women (ORquintile 5 vs 1 = 0.46, 95% CI = 0.34 to 0.62). These associations changed minimally when we included both absolute dense area and absolute nondense area in the same statistical model. As expected, the percentage dense area was the strongest risk factor for breast cancer in both groups.ConclusionsOur results indicate that absolute dense area is independently and positively associated with breast cancer risk, whereas absolute nondense area is independently and inversely associated with breast cancer risk. Since adipose tissue is radiographically nondense, these results suggest that adipose breast tissue may have a protective role in breast carcinogenesis.

Tolerance and safety evaluation ofN,N-dimethylglycine, a naturally occurring organic compound, as a feed additive in broiler diets

N,N-Dimethylglycine (DMG) is a tertiary amino acid that naturally occurs as an intermediate metabolite in choline-to-glycine metabolism. The objective of the present trial was to evaluate tolerance, safety and bioaccumulation of dietary DMG in broilers when supplemented at 1 g and 10 g Na-DMG/kg. A feeding trial was conducted using 480 1-d-old broiler chicks that were randomly allocated to twenty-four pens and fed one of three test diets added with 0, 1 or 10 g Na-DMG/kg during a 39 d growth period. Production performance was recorded to assess tolerance and efficacy of the supplement. At the end of the trial, toxicity was evaluated by means of haematology, plasma biochemistry and histopathology of liver, kidney and heart (n 12), whereas bioaccumulation was assessed on breast meat, liver, blood, kidney and adipose tissue (n 8). Carcass traits were similar between the control and 1 g Na-DMG/kg feed groups (P>0·05), but the feed:gain ratio was significantly improved at 1 g Na-DMG/kg feed compared with the control or the 10-fold dose (P=0·008). Histological examinations showed no pathological effects and results of haematology and plasma biochemistry revealed similar values between the test groups (P>0·05). Bioaccumulation occurred at the 10-fold dose, but the resulting DMG content in breast meat was comparable with, for instance, wheat bran and much lower than uncooked spinach. In conclusion, DMG at 1 g Na-DMG/kg improved the feed:gain ratio in broilers without DMG being accumulated in consumer parts. Furthermore, dietary supplementation with DMG up to 10 g Na-DMG/kg did not induce toxicity or impaired performance in broilers.

Energy absorption buildup factors of human organs and tissues at energies and penetration depths relevant for radiotherapy and diagnostics

Energy absorption geometric progression (GP) fitting parameters and the corresponding buildup factors have been computed for human organs and tissues, such as adipose tissue, blood (whole), cortical bone, brain (grey/white matter), breast tissue, eye lens, lung tissue, skeletal muscle, ovary, testis, soft tissue, and soft tissue (4‐component), for the photon energy range 0.015–15 MeV and for penetration depths up to 40 mfp (mean free path). The chemical composition of human organs and tissues is seen to influence the energy absorption buildup factors. It is also found that the buildup factor of human organs and tissues changes significantly with the change of incident photon energy and effective atomic number, Zeff. These changes are due to the dominance of different photon interaction processes in different energy regions and different chemical compositions of human organs and tissues.With the proper knowledge of buildup factors of human organs and tissues, energy absorption in the human body can be carefully controlled. The present results will help in estimating safe dose levels for radiotherapy patients and also useful in diagnostics and dosimetry. The tissue‐equivalent materials for skeletal muscle, adipose tissue, cortical bone, and lung tissue are also discussed. It is observed that water and MS20 are good tissue equivalent materials for skeletal muscle in the extended energy range.PACS numbers: 32.80‐t, 87.53‐j, 78.70‐g, 78.70‐Ck

Sex steroid hormone levels in breast adipose tissue and serum in postmenopausal women

Elevated levels of circulating estrogens and androgens are linked to higher breast cancer risk among postmenopausal women; however, little is known about hormone levels within the breast. Hormone concentrations within the breast may not be reflected in the blood and are likely important contributors to breast carcinogenesis. We used a previously validated method to measure levels of estrone, estradiol, androstenedione, and testosterone in adipose tissue removed as part of breast excisions performed for cancer in 100 postmenopausal women (69 ER/PR +/+ and 31 ER/PR -/-) participating in a breast cancer case-control study. We also measured the same steroid hormones, as well as estrone sulfate, and sex hormone-binding globulin (SHBG) in serum from these patients and 100 controls matched on ages at blood collection and on menopause. Overall, concentrations of serum hormones did not vary significantly between controls and cases. However, women with ER-/PR- breast cancers had lower circulating levels of all measured sex steroid hormones and higher SHBG levels than women with ER+/PR+ breast cancers and controls. Similarly, hormone concentrations in breast adipose tissue were higher among women with ER+/PR+ compared to ER-/PR- breast cancer, although differences were only significant for testosterone. These data demonstrate that high sex steroid concentrations in both serum and adipose tissues are more strongly related to ER+/PR+ than ER-/PR- breast cancers. Measurement of sex hormones in serum and in the microenvironment may help in understanding the hormonal etiology of breast cancer, suggest methods for prevention, and have value in gauging treatment response and prognosis.