Abstract 2524: Cytology in nipple aspirate fluid during a randomized soy food intervention among premenopausal women

Background. Epidemiologic studies support the hypothesis that soy foods protect against breast cancer, in particular among Asian populations with high intake. A previous report that observed an increase in the number of women with hyperplasic epithelial cells after consuming soy raised concerns that isoflavones in soy may elevate breast cancer risk due to their estrogen-like structure. We examined the effect of a high-soy diet on the presence of epithelial cells in nipple aspirate fluid (NAF), a non-invasive method to obtain breast fluid and cells.

Methods. In a crossover design, 82 premenopausal women completed a randomized intervention with a high-soy diet of 2 servings/day and a low-soy diet with <3 servings/week for 6 months each separated by a 1-month washout period. Adherence to the intervention strategy was excellent as assessed by urinary isoflavonoid excretion and by 7 unannounced 24-hour dietary recalls. NAF samples were obtained at baseline, after 6 months, and after 13 months. Papanicolaou-stained cytology slides were evaluated in women with sufficient NAF and classified as inadequate (<10) mammary epithelial cells (class I), benign mammary epithelial cells (class II), atypical mammary epithelial cells (class III), and malignant cells present (class IV). Mixed models were applied to examine the effect of the high-soy diet on epithelial cytology as compared to baseline and the low-soy diet.Results. The mean NAF volumes for women with and without cytology specimens differed significantly; they were 58±49 vs. 19±16 μL at baseline, 59±37 vs. 13±14 μL at the end of the high-soy diet period, and 51±40 vs. 10±9 μL at the end of the low-soy diet period. At baseline, 33 women produced sufficient NAF for cytological evaluation, 36 women at the end of the high-soy diet, and 24 women at the end of the low-soy diet. For 22 (67%) participants, no change in cytological class was seen at the end of the high-soy diet and for 12 (57%) at the end of the low-soy diet, but a decrease from baseline to the end of the high-soy diet occurred in 8 (24%) and an increase in 3 (9%) women. In comparison, a decrease in 3 (14%) and an increase in 6 (29%) women was seen at the end of the low-soy diet. Although not statistically significant (p=0.05), the high-soy diet was associated with a trend in lower cytological class. Conclusions. Contrary to an earlier report, the number of NAF samples with hyperplastic epithelial cells did not increase after an intervention with soy foods in amounts consumed by Asians.

Citation Format: Gertraud Maskarinec, Shana Suzuki, Yukiko Morimoto, Ian Pagano, Adrian A. Franke, Hormoz Ehya. Cytology in nipple aspirate fluid during a randomized soy food intervention among premenopausal women. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2524. doi:10.1158/1538-7445.AM2013-2524

Mammographic density as a predictor of breast cancer survival: the Multiethnic Cohort

Introduction

Mammographic density, a strong predictor for breast cancer incidence, may also worsen prognosis in women with breast cancer. This prospective analysis explored the effect of prediagnostic mammographic density among 607 breast cancer cases diagnosed within the Hawaii component of the Multiethnic Cohort (MEC).

Methods

Female MEC participants, aged ≥ 50 years at cohort entry, diagnosed with primary invasive breast cancer, and enrolled in a mammographic density case-control study were part of this analysis. At cohort entry, anthropometric and demographic information was collected by questionnaire. Tumor characteristics and vital status were available through linkage with the Hawaii Tumor Registry. Multiple digitized prediagnostic mammograms were assessed for mammographic density using a computer-assisted method. Cox proportional hazards regression was applied to examine the effect of mammographic density on breast cancer survival while adjusting for relevant covariates.

Results

Of the 607 cases, 125 were diagnosed as in situ, 380 as localized, and 100 as regional/distant stage. After a mean follow-up time of 12.9 years, 27 deaths from breast cancer and 100 deaths from other causes had occurred; 71 second breast cancer primaries were diagnosed. In an overall model, mammographic density was not associated with breast cancer-specific survival (HR = 0.95 per 10%; 95%CI: 0.79-1.15), but the interaction with radiotherapy was highly significant (p = 0.006). In stratified models, percent density was associated with a reduced risk of dying from breast cancer (HR = 0.77; 95%CI: 0.60-0.99; p = 0.04) in women who had received radiation, but with an elevated risk (HR = 1.46; 95% CI: 1.00-2.14; p = 0.05) in patients who had not received radiation. High breast density predicted a borderline increase in risk for a second primary (HR = 1.72; 95% CI: 0.88-2.55; p = 0.15).

Conclusions

Assessing mammographic density in women with breast cancer may identify women with a poorer prognosis and provide them with radiotherapy to improve outcomes.

Non-hodgkin lymphoma and circulating markers of inflammation and adiposity in a nested case-control study: the multiethnic cohort

BACKGROUND

Because immune dysfunction is thought to underlie the development of non-Hodgkin lymphoma (NHL), obesity and chronic inflammation may be involved in its etiology. We examined the association of prediagnostic inflammatory markers and adipokines with NHL risk.

METHODS

We conducted a nested case-control analysis (272 cases and 541 matched controls) within the Multiethnic Cohort. Luminex technology was used to measure a 10-plex panel of cytokines, ELISA assays for adipokines, and an autoanalyzer for C-reactive protein (CRP). ORs and 95% confidence intervals (CI) for tertiles of analytes were estimated by conditional logistic regression.

RESULTS

After a median time of 2.7 years from phlebotomy to diagnosis, interleukin (IL)-10 was significantly related to NHL risk (ORT3 vs. T1 = 3.07; 95%CI, 2.02-4.66; Ptrend < 0.001). TNF-α and IL-8 showed borderline elevated risks, whereas IFN-γ, IL-1β, IL-2, IL-4, IL-5, IL-6, and CRP were not associated with NHL. Leptin but not adiponectin was related to NHL risk (ORT3 vs. T1 = 0.48; 95%CI, 0.30-0.76; Ptrend < 0.001). Adjustment for body mass index did not substantially affect the risk estimates. Stratification by subtype indicated significant associations with IL-10 and leptin for follicular but not for diffuse large B-cell lymphoma. Excluding cases diagnosed less than 1 year after phlebotomy attenuated all associations.

CONCLUSIONS

IL-10 was the only cytokine and leptin the only adipokine associated with NHL, but due to the short follow-up time, preclinical effects cannot be excluded.

IMPACT

Although markers of inflammation and adiposity may provide new insights into the etiology of NHL, they need to be assessed many years before clinical diagnosis.

Plasma matrix metalloproteinases and postmenopausal breast cancer risk: a nested case-control study in the Multiethnic Cohort study

The survival of malignant breast cells depends upon the remodeling of the extracellular matrix, including complex interactions with matrix metalloproteinases (MMPs). It has been hypothesized that circulating MMPs may serve as early indicators of breast cancer development in hospital-based case-control studies. A nested case-control study of the association of pre-diagnostic plasma levels of MMPs with the subsequent risk of postmenopausal breast cancer was conducted within the Multiethnic Cohort. During the follow-up period, 713 women with incident invasive breast cancer were identified and individually (1:1) matched to controls. Four types of MMPs (1, 2, 3, and 7) were analyzed by microsphere immunofluorescence assay. Mean plasma levels of MMPs did not differ significantly between cases and controls; nor were there differences in breast cancer risk by MMP level. No difference in the risk of breast cancer by plasma level of the MMPs was found within strata of age, or ethnicity, although MMP-1 levels were positively associated with breast cancer risk in obese women and women by hormone replacement medications (P values for interaction <0.05). Few significant differences in risk by levels of the MMPs were found by any of the clinical variables. Circulating MMPs were not associated with postmenopausal breast cancer risk.

Complementary and alternative medicine use and breast cancer prognosis: a pooled analysis of four population-based studies of breast cancer survivors

BACKGROUND

Complementary and alternative medicine (CAM) use is common among breast cancer survivors, but little is known about its impact on survival.

METHODS

We pooled data from four studies conducted in Hawaii in 1994-2003 and linked to the Hawaii Tumor Registry to obtain long-term follow-up information. The effect of CAM use on the risk of breast cancer-specific death was evaluated using Cox regression.

RESULTS

The analysis included 1443 women with a median follow-up of 11.8 years who had a primary diagnosis of in situ and invasive breast cancer. The majority were Japanese American (36.4%), followed by white (26.9%), Native Hawaiian (15.9%), other (10.6%), and Filipino (10.3%). CAM use was highest in Native Hawaiians (60.7%) and lowest in Japanese American (47.8%) women. Overall, any use of CAM was not associated with the risk of breast cancer-specific death (hazard ratio [HR] 1.47, confidence interval [CI] 0.91-2.36) or all-cause death (HR 0.82, 95% CI 0.63-1.06). However, energy medicine was associated with an increased risk of breast cancer-specific death (HR 3.19, 95% CI 1.06-8.52). When evaluating CAM use within ethnic subgroups, Filipino women who used CAM were at increased risk of breast cancer death (HR 6.84, 95% CI 1.23-38.19).

CONCLUSIONS

Our findings suggest that, overall, CAM is not associated with breast cancer-specific death but that the effects of specific CAM modalities and possible differences by ethnicity should be considered in future studies.

Higher alcohol intake may modify the association between mammographic density and breast cancer: an analysis of three case-control studies

Alcohol consumption and mammographic density are established risk factors for breast cancer. This study examined whether the association of mammographic density with breast cancer varies by alcohol intake. Mammographic density was assessed in digitized images for 1207 cases and 1663 controls from three populations (Japan, Hawaii, California) using a computer-assisted method. Associations were estimated by logistic regression. When comparing ever to never drinking, mean density was similar and consumption was not associated with breast cancer risk. However, within the Hawaii/Japan subset, women consuming >1 drink/day had a non-significantly elevated relative risk compared to never drinkers. Also in the Hawaii/Japan population, alcohol intake only modified the association between mammographic density and breast cancer in women consuming >1 drink/day (p(interaction)=0.05) with significant risk estimates of 3.65 and 6.58 for the 2nd and 3rd density tertiles as compared to 1.57 and 1.61 for never drinkers in Hawaii/Japan. Although these findings suggest a stronger association between mammographic density and breast cancer risk for alcohol consumers, the small number of cases requires caution in interpreting the results.

Common breast cancer susceptibility variants in LSP1 and RAD51L1 are associated with mammographic density measures that predict breast cancer risk

BACKGROUND

Mammographic density adjusted for age and body mass index (BMI) is a heritable marker of breast cancer susceptibility. Little is known about the biologic mechanisms underlying the association between mammographic density and breast cancer risk. We examined whether common low-penetrance breast cancer susceptibility variants contribute to interindividual differences in mammographic density measures.

METHODS

We established an international consortium (DENSNP) of 19 studies from 10 countries, comprising 16,895 Caucasian women, to conduct a pooled cross-sectional analysis of common breast cancer susceptibility variants in 14 independent loci and mammographic density measures. Dense and nondense areas, and percent density, were measured using interactive-thresholding techniques. Mixed linear models were used to assess the association between genetic variants and the square roots of mammographic density measures adjusted for study, age, case status, BMI, and menopausal status.

RESULTS

Consistent with their breast cancer associations, the C-allele of rs3817198 in LSP1 was positively associated with both adjusted dense area (P = 0.00005) and adjusted percent density (P = 0.001), whereas the A-allele of rs10483813 in RAD51L1 was inversely associated with adjusted percent density (P = 0.003), but not with adjusted dense area (P = 0.07).

CONCLUSION

We identified two common breast cancer susceptibility variants associated with mammographic measures of radiodense tissue in the breast gland.

IMPACT

We examined the association of 14 established breast cancer susceptibility loci with mammographic density phenotypes within a large genetic consortium and identified two breast cancer susceptibility variants, LSP1-rs3817198 and RAD51L1-rs10483813, associated with mammographic measures and in the same direction as the breast cancer association.

Physical activity and risk of type 2 diabetes among Native Hawaiians, Japanese Americans, and Caucasians: the Multiethnic Cohort

BACKGROUND

Physical inactivity is an established risk factor for diabetes; however, little is known about this association across ethnic groups with different diabetes risk. Therefore, we evaluated the association between physical activity and diabetes and potential effect modification by ethnicity in the Hawaii component of the Multiethnic Cohort.

METHODS

Participants, aged 45 to 75 years, were enrolled by completing a questionnaire on demographics, diet, and self-reported weekly hours of strenuous sports, vigorous work, and moderate activity. Among the 74,913 participants (39% Caucasian, 14% Native Hawaiian, 47% Japanese American), 8561 incident diabetes cases were identified by self-report, a medication questionnaire, and through health plan linkages. Cox regression was applied to estimate hazard ratios (HR) and 95% confidence intervals (95%CI) while adjusting for known confounders.

RESULTS

Engaging in strenuous sports was inversely related to diabetes risk with HRs (4+ hours/week vs. never) of 0.67 (95%CI: 0.57-0.79) in women and 0.80 (95%CI: 0.72-0.88) in men. In stratified analyses, the inverse association was consistent across ethnic groups. The inverse association of vigorous work with diabetes was limited to men, while beneficial effects of moderate activity were observed only in Caucasians.

CONCLUSIONS

These findings support a role of high-intensity physical activity and ethnic-specific guidelines in diabetes prevention.

Urinary estrogen metabolites in two soy trials with premenopausal women

Background

Soy consumption may protect against breast cancer through modification of estrogen metabolism.

Objective

We examined the effect of soy foods on urinary estrogens and the 2-hydroxy (OH)/16α-OH estrone (E₁) ratio in 2 dietary interventions with premenopausal women.

Methods

BEAN1 was a 2-year randomized trial and BEAN2 a 13-month randomized crossover study. In both interventions, study participants consumed a high-soy diet with 2 soy food servings/day and a low-soy diet with <3 servings of soy/week. Urine samples were collected at baseline and at the end of the diet periods, analyzed for 9 estrogen metabolites by liquid chromatography mass spectrometry, and adjusted for creatinine levels. For BEAN1, 2 samples for 188 participants and for BEAN2, 3 samples for 79 women were analyzed. We applied mixed-effects regression models with log-transformed values of estrogen metabolites and soy intake as the exposure variable.

Results

In BEAN1, no effect of the high-soy diet on individual estrogen metabolites or hydroxylation pathways was observed. The median 2-OH/16α-OH E₁ ratio decreased non-significantly in the intervention group from 6.2 to 5.2 as compared to 6.8 and 7.2 in the control group (p=0.63). In BEAN2, only 4-OHE₁ was significantly lower after the high-soy diet. Interaction terms of the high-soy diet with equol producer status, ethnicity, and weight status revealed no significant effect modification.

Conclusions

Contrary to our hypothesis and some previous reports, the results from 2 well controlled dietary interventions do not support an effect of a high-soy diet on a panel of urinary estrogen metabolites and the 2-OH/16α-OHE₁ ratio.

Abstract 663: Circulating lipids and fatty acids and non-Hodgkin lymphoma risk in a nested case-control study: The Multiethnic Cohort

Objective: Dietary fatty acids provide important components of immune cells, cytokines, and prostaglandins. Intake of n-3 and n-6 polyunsaturated fatty acids may influence inflammatory responses that contribute to the risk of non-Hodgkin lymphoma (NHL). Because saturated and polyunsaturated fatty acid (SFA and PUFA) intake has been linked with NHL, this analysis evaluated biomarkers of dietary fat intake in relation to risk. Methods: We conducted a nested-case control analysis (275 cases and 549 controls) within the Multiethnic Cohort Study (Caucasians, Japanese Americans, Latinos, African Americans, and Native Hawaiians) to examine NHL risk by tertile of erythrocyte membrane fatty acid composition and serum lipid concentrations. Cases were matched to 2 controls by sex, year of birth, ethnicity, location (CA or HI), date and time of blood draw, and fasting hours before blood draw. Fatty acids were measured as the percentage of total measured erythrocyte membrane fatty acids using gas chromatography, and absolute serum levels of total, high density-lipoprotein (HDL), and low density-lipoprotein (LDL) cholesterol and triglycerides were measured using an automated chemical analyzer (Cobas MiraPlus, Roche Diagnostics, Switzerland). Conditional logistic regression was applied to estimate odds ratios (OR) and 95% confidence intervals (CI) with adjustment for potential confounders. Results: The mean ages at blood draw were 70.1±7.4 and 70.2±7.4 years for cases and controls, respectively. The cases (82 diffuse large B-cell, 52 small cell/chronic lymphocytic leukemia, 49 follicular, 15 T-cell, and 77 others) were diagnosed 3.1±2.3 years after the blood draw. Higher prediagnostic serum lipids, in particular total (ORT3 vs T1: 0.5 [95% CI: 0.4, 0.8]; ptrend &lt;0.001) and HDL cholesterol (ORT3 vs T1: 0.5 [0.3, 0.8]; ptrend &lt;0.01) but not triglycerides were associated with a lower NHL risk. No significant associations were found for individual fatty acids, the n-3/n-6 fatty acid or the PUFA/SFA ratio. Stratification by sex and ethnicity suggested significant heterogeneity. For example, in women but not in men, n-6 fatty acids were associated with a higher NHL risk (ptrend =0.09) and the PUFA/SFA ratio with a lower risk (ptrend =0.05). Monounsaturated fatty acids reduced risk in Caucasians (ptrend =0.01) while higher risks were observed for stearic acid (C18:0; ptrend &lt;0.01) in Japanese Americans and for palmitic acid (C16:0; ptrend &lt;0.01) in African Americans. Conclusions: Individual fatty acids showed no relation with overall NHL risk in this multiethnic population, but possible sex- or ethnicity-specific influences may exist. Total and HDL cholesterol levels, which reflect dietary and non-dietary factors, were associated with a reduced risk. Replication of these findings in other cohort studies is warranted.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 663. doi:1538-7445.AM2012-663

Abstract 5474: Prediagnostic cytokine levels and the risk of non-Hodgkin lymphoma in a nested case-control study: The Multiethnic Cohort

Objective: Since immune dysfunction is thought to be the underlying basis for the development of Non-Hodgkin Lymphoma (NHL), obesity and a state of chronic inflammation may increase the risk of the disease. The objective of this analysis was to examine the association of prediagnostic inflammatory marker and adipokine levels in serum with NHL risk. Methods: We conducted a nested case-control analysis (272 cases and 578 controls) within the Multiethnic Cohort Study, which consists of Caucasians, Japanese Americans, Latinos, African Americans, and Native Hawaiians in California and Hawaii. Each case was matched to 2 controls by sex, year of birth, ethnicity, location (HI or CA), date and time of blood draw, and fasting hours before blood draw. A 10-plex panel of cytokines (TNF-α, IFN-γ, GM-CSF, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, and IL-10) was measured in prediagnostic blood samples by Luminex multiplex technology. ELISA assays were used for the adipokines, and CRP was assessed using a Cobas MiraPlus clinical chemistry analyzer. Tertiles of analytes were created and conditional logistic regression was applied to estimate the odds ratios (OR) and 95% confidence intervals (CI), with adjustment for age at blood draw, alcohol, smoking status, and body mass index (BMI). Results: The mean ages at blood draw were 70.0±7.4 and 70.3±7.6 years for cases and controls, respectively. The mean time from blood draw to diagnosis was 3.1±2.3 years with NHL cases comprised of the following lymphoma: 82 diffuse large B-cell, 51 small cell/chronic lymphocytic leukemia, 49 follicular, 15 T-cell, and 75 others. Of all cytokines, IL-10, IL-6, and IL-8 were positively associated with risk for NHL. The respective BMI-adjusted ORsT3v vs T1 were 3.1 (95%CI: 2.0-4.7; ptrend &lt;0.0001), 1.3 (95%CI: 0.9-1.9; ptrend=0.09), and 1.5 (95%CI: 1.0-2.2; ptrend=0.11). No significant associations were observed for TNF-α, IFN-γ, GM-CSF, IL-1β, IL-2, IL-4, IL-5, and CRP. Leptin levels were inversely associated with NHL risk, with a stronger association after adjustment for BMI (ORT3v vs T1 = 0.3, 95%CI: 0.2-0.5; ptrend&lt;0.001), but adiponectin was not related to risk. The lower risk associated with higher leptin levels was present in normal and in overweight/obese individuals. We did not observe any heterogeneity by sex or ethnicity for cytokines and adipokines. Conclusions: Contrary to expectation, higher IL-10 levels were associated with a higher NHL risk, and higher leptin levels were related to a lower NHL risk, even after adjustment for BMI. The limited sample size and the relatively short time between blood draw and diagnosis may have contributed to these findings.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5474. doi:1538-7445.AM2012-5474

Various adiposity measures show similar positive associations with type 2 diabetes in Caucasians, native Hawaiians, and Japanese Americans: the multiethnic cohort

The authors evaluated the association of body mass index (BMI), waist circumference (WC) and hip circumference (HC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR) with diabetes in Caucasians, Native Hawaiians, and Japanese Americans aged 45 to 75 years in the Multiethnic Cohort. Diabetes cases were obtained from self-reports and by linkages with health insurance plans. The authors estimated adjusted prevalence odds ratios (PORs) and compared the area under the receiver operating characteristic curves (AUC). All measures were positively associated with diabetes prevalence; the PORs were 1.25 to 1.64 in men and 1.52 to 1.83 in women. In all 3 ethnic groups, the AUCs in men were greater for BMI than for the other measures, whereas in women, the AUCs were greater for combined models than for BMI alone, but the differences were small and not clinically significant. It does not appear that one anthropometric measure best reflects diabetes prevalence or performs better in one ethnic group than in another.

Equol production changes over time in pre-menopausal women

Equol (EQ) is a metabolite produced by gut bacteria through the chemical reduction of the soya isoflavone daidzein (DE), but only by 30-60% of the population. EQ is believed to provide benefits derived from soya intake and its production is widely viewed as a relatively stable phenomenon. In a randomised, cross-over intervention with soya foods, seventy-nine pre-menopausal women were challenged with a high-soya and a low-soya diet each for 6 months, separated by a 1-month washout period. Overnight urine was collected at three time points during each diet period and analysed for DE and EQ by liquid chromatography tandem MS. Remaining an EQ producer (EP) or non-producer (NP) or changing towards an EP or NP was assessed using an EQ:DE ratio of ≥0·018 combined with a DE threshold of ≥2 nmol/mg creatinine as a cut-off point. We observed 19 and 24% EP during the low-soya and high-soya diet periods, respectively, and found that 6-11% of our subjects changed EQ status 'within' each study period (on an average of 1·2 times), while 16% changed 'between' the two diet periods. The present finding challenges the widely held conviction that EQ production within an individual remains stable over time. The precise factors contributing to changes in EQ status, however, remain elusive and warrant further investigation.

Ethnic differences in breast cancer survival: status and determinants

Ethnic differences in breast cancer survival have been a long-standing concern. The objective of this article is to present relevant studies for all major US racial/ethnic groups including African-Americans, Latinos, Native Americans, Japanese-Americans and Native Hawaiians, and to discuss underlying causes of disparity. In comparison to Caucasian women, African-American women continue to experience the poorest breast cancer-specific survival of all ethnic groups in the USA. The prognosis for Latinos, Native Hawaiians and Native Americans is intermediate, better than for African-Americans but not as good as for Caucasians, whereas Japanese-American women tend to have better outcomes. The following possible contributors to the observed differences are discussed in detail: unfavorable distribution of stage at diagnosis due to low screening rates, limited access to care and treatment, tumor type, comorbidities, socioeconomic status, obesity and physical activity.

Soy foods and urinary isoprostanes: results from a randomized study in premenopausal women

In addition to their antiestrogenic effects, soy isoflavones may protect against cancer through alternate biological actions, for example, antioxidant properties. This randomized crossover study explored the relationship between dietary isoflavone intake through common soy foods and oxidative stress quantified by urinary isoprostane levels. Eighty-two women aged 39.2 ± 6.1 years were randomly selected to receive a high soy diet of 2 soy food servings per day and a low soy diet of <3 servings per week for 6 months each, separated by a 1-month washout period. Urine samples were collected at baseline and at the end of each dietary period. Urinary isoprostane levels were measured using enzyme-linked immunosorbent assays (ELISA) and adjusted for creatinine levels. Mixed models using log-transformed values were applied to evaluate the effect of the high soy diet. Unadjusted isoprostane excretion levels were lower during the high rather than the low soy diet, but this effect was not statistically significant (p = 0.81). After adjustment for urinary creatinine, isoprostane excretion was slightly higher during the high soy diet (p = 0.02), an observation that was confirmed in a regression analysis between urinary isoflavones and isoprostanes during the high soy diet. The original association remained significant when restricted to adherent participants, however this effect disappeared after exclusion of three extreme values. In agreement with several previous reports, these findings do not support the hypothesis that soy exerts antioxidant effects, as measured by urinary isoprostane excretions, but additional markers of oxidative stress need to be investigated in future studies.

Asian ethnicity is associated with a higher trunk/peripheral fat ratio in women and adolescent girls

Background

Ethnic differences in body fat mass and distribution may develop in childhood and contribute to increased obesity-related disease risk among Asians. We used dual-energy X-ray absorptiometry (DXA) to evaluate adiposity measures among adult women and their adolescent daughters, who were of predominantly Japanese and white ethnicity.

Methods

We obtained DXA whole body scans for 101 mothers aged 30 years or older and 112 daughters aged 10 to 16 years. The participants were classified as Asian, part-Asian, mixed/other, or white. As a measure of central adiposity, we calculated the trunk/peripheral fat ratio (TPFR). General linear models were used to evaluate differences in adiposity measures by ethnic category.

Results

In mothers, TPFR was significantly higher (P_trend < 0.01) in Asians and part-Asians (1.38 ± 0.42 and 1.32 ± 0.51) than in mixed/others and whites (1.18 ± 0.27 and 1.09 ± 0.21). The trend was similar among daughters (P_trend < 0.001), with respective values of 1.09 ± 0.18, 0.97 ± 0.17, 0.99 ± 0.16, and 0.87 ± 0.11. Among mothers, gynoid fat mass and peripheral fat mass were significantly lower in Asians than in whites, whereas none of the regional DXA adiposity measures differed by ethnicity in daughters.

Conclusions

These results confirm previous reports of greater central adiposity in women of Asian ancestry and indicate that ethnic differences in adiposity are already present in adolescence.

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.

Mammographic density, parity and age at first birth, and risk of breast cancer: an analysis of four case-control studies

Mammographic density is strongly and consistently associated with breast cancer risk. To determine if this association was modified by reproductive factors (parity and age at first birth), data were combined from four case-control studies conducted in the United States and Japan. To overcome the issue of variation in mammographic density assessment among the studies, a single observer re-read all the mammograms using one type of interactive thresholding software. Logistic regression was used to estimate odds ratios (OR) while adjusting for other known breast cancer risk factors. Included were 1,699 breast cancer cases and 2,422 controls, 74% of whom were postmenopausal. A positive association between mammographic density and breast cancer risk was evident in every group defined by parity and age at first birth (OR per doubling of percent mammographic density ranged between 1.20 and 1.39). Nonetheless, the association appeared to be stronger among nulliparous than parous women (OR per doubling of percent mammographic density = 1.39 vs. 1.24; P interaction = 0.054). However, when examined by study location, the effect modification by parity was apparent only in women from Hawaii and when examined by menopausal status, it was apparent in postmenopausal, but not premenopausal, women. Effect modification by parity was not significant in subgroups defined by body mass index or ethnicity. Adjusting for mammographic density did not attenuate the OR for the association between parity and breast cancer risk by more than 16.4%, suggesting that mammographic density explains only a small proportion of the reduction in breast cancer risk associated with parity. In conclusion, this study did not support the hypothesis that parity modifies the breast cancer risk attributed to mammographic density. Even though an effect modification was found in Hawaiian women, no such thing was found in women from the other three locations.

Influence of diet on nipple aspirate fluid production and estrogen levels

One possible mechanism how nutritional factors may affect breast cancer risk is through an influence on estrogen levels. Nipple aspirate fluid (NAF) is thought to provide a more direct insight into hormonal influences on breast tissue than serum. The ability to produce NAF may be an indicator of breast cancer risk. The current analysis was conducted as part of a soy trial in 92 premenopausal women and evaluated the relation of usual dietary intake with NAF volume and the most predominant steroidal estrogens in NAF and serum at baseline. Estradiol (E(2)) and estrone sulfate (E(1)S) were assessed in NAF and E(2), estrone (E(1)), and E(1)S, in serum using highly sensitive radioimmunoassays. The statistical analysis applied multivariate, log-linear regression models. Intake of saturated fat and cheese (p = 0.06 for both) indicated a positive trend with NAF volume whereas isoflavonoid and soy consumption suggested inverse associations (p = 0.01 and p = 0.08). For estrogens in NAF, total fat and monounsaturated fat intake was positively associated with E(2) (p = 0.05 and p = 0.02) and in serum, alcohol intake was associated with higher E(1)S levels (p = 0.02). These findings suggest a weak influence of dietary composition on NAF production and estrogen levels in serum and NAF.