Circulating 27-hydroxycholesterol, lipids, and steroid hormones in breast cancer risk: a nested case-control study of the Multiethnic Cohort Study.

BACKGROUND: Laboratory studies have indicated that a cholesterol metabolite and selective estrogen receptor modulator, 27-hydroxycholesterol (27HC), may be important in breast cancer etiology and explain associations between obesity and postmenopausal breast cancer risk. Epidemiologic evidence for 27HC in breast cancer risk is limited, particularly in multiethnic populations. METHODS: In a nested case-control study of 1470 breast cancer cases and 1470 matched controls within the Multiethnic Cohort Study, we examined associations of pre-diagnostic circulating 27HC with breast cancer risk among African American, Japanese American, Native Hawaiian, Latino, and non-Latino White postmenopausal females. We used multivariable logistic regression adjusted for age, education, parity, body mass index, and smoking status. Stratified analyses were conducted across racial and ethnic groups, hormone receptor (HR) status, and use of lipid-lowering drugs. We assessed interactions of 27HC with steroid hormones. RESULTS: 27HC levels were inversely related to breast cancer risk (odds ratio [OR] 0.80; 95% confidence interval [CI] 0.58, 1.12), but the association was not statistically significant in the full model. Directions of associations differed by racial and ethnic group. Results suggested an inverse association with HR-negative breast cancer (OR 0.46; 95% CI 0.20, 1.06). 27HC interacted with testosterone, but not estrone, on risk of breast cancer; 27HC was only inversely associated with risk among those with the highest levels of testosterone (OR 0.46; 95% CI 0.24, 0.86). CONCLUSION: This is the first US study to examine circulating 27HC and breast cancer risk and reports a weak inverse association that varies across racial and ethnic groups and testosterone level.

Association of Adiposity Phenotypes with 27-Hydroxycholesterol and Sex Hormones: The Multiethnic Cohort Study.

CONTEXT: The distribution of body fat has been linked to circulating levels of lipids and sex-steroid hormones. The cholesterol metabolite and endogenous selective estrogen receptor modulator, 27-hydroxychlolesterol (27HC), may be influenced by adiposity phenotypes, particularly among females. No study has examined the relationships of 27HC and steroid hormones with adiposity phenotypes. OBJECTIVE: To investigate the associations of 27HC and steroid hormones with detailed adiposity phenotypes among a multiethnic population of postmenopausal females. METHODS: A cross-sectional study was conducted among 912 postmenopausal females from the Multiethnic Cohort- Adiposity Phenotype study. Multivariable linear regression examined the associations of circulating levels of 27HC, steroid hormones, and sex hormone-binding globulin (SHBG) with detailed adiposity phenotypes, adjusting for demographics, lifestyle factors, diabetes status, and use of lipid lowering drugs. Subgroup analyses were conducted across race and ethnicity. RESULTS: Total fat mass (P-trend=0.003), subcutaneous adipose tissue (SAT) (P-trend=0.006), and superficial subcutaneous adipose tissue (sSAT) (P-trend=4.41x10-4) were inversely associated with circulating 27HC levels. In contrast, visceral adipose tissue (VAT) (P-trend=0.003) and liver fat (P-trend=0.005) were positively associated with 27HC levels. All adiposity phenotypes were associated with higher levels of free estradiol, testosterone and lower levels of SHBG. Generally, similar patterns of associations were observed across race and ethnicity. CONCLUSION: Adiposity phenotypes, such as SAT, VAT, and liver fat, were differentially associated with circulating 27HC, while consistent directions of associations were seen for circulating hormones among postmenopausal females. Future studies are warranted to further understand the biology and relationships of 27HC and adiposity-related diseases.

Impact of diet on mortality from stroke: results from the U.S. multiethnic cohort study.

OBJECTIVES: Stroke is the fourth leading cause of death in the United States and stroke mortality rates vary by ethnicity. The purpose of this study was to examine the associations between food group consumption and risk of death from stroke among 5 ethnic groups in the United States. METHODS: The Multiethnic Cohort includes >215,000 participants, the majority of whom are African American, Native Hawaiian, Japanese American, Latino, and Caucasian men and women recruited by mail survey in Hawaii and Los Angeles in 1993-1996. Deaths from stroke were identified by linkage to the state death files and the U.S. National Death Index. Diet was assessed using a validated food frequency questionnaire. Associations were examined using multivariable Cox proportional hazards models, stratified by ethnicity and gender. RESULTS: A total of 860 deaths from stroke were identified among the cohort participants. Vegetable intake was associated with a significant reduction in risk for fatal stroke among African American women (relative risk [RR]=0.60; 95% CI: 0.36-0.99). Among Japanese American women only, high fruit intake was significantly associated with a risk reduction for stroke mortality (RR=0.43; 95% confidence interval [CI]: 0.22-0.85), whereas meat intake increased risk (RR=2.36; 95% CI: 1.31-4.26). Among men, a significant reduction in stroke mortality was observed among Native Hawaiians (RR=0.26; 95% CI: 0.07-0.95). After pooling the data for the ethnic groups, the findings support an elevated risk for high meat intake among women overall (RR=1.56; 95% CI: 1.12-2.16); no significant effects of dietary intake on risk for fatal stroke were observed among men. CONCLUSIONS: Although some variations were observed for the associations between diet and stroke mortality among ethnic groups, the findings suggest that these differences are not substantial and may be due to dietary intake of specific food subgroups. Additional investigations including dietary subgroups and nutrients sources are needed to clarify these findings.

No Association of Trichomonas vaginalis Seropositivity with Advanced Prostate Cancer Risk in the Multiethnic Cohort: A Nested Case-Control Study.

The potential involvement of a sexually transmitted agent has been suggested to contribute to the high number of prostate cancers in the United States and worldwide. We investigated the relationship of Trichomonas vaginalis seropositivity with prostate cancer risk in a nested case-control study within the Multiethnic Cohort in Hawaii and California using blood samples collected prior to cancer diagnoses. Incident cases of advanced prostate cancer (intermediate- to high-grade based on Gleason score ≥ 7 and/or disease spread outside the prostate) were matched to controls by age, ethnicity, and the date of blood collection. T. vaginalis serostatus was measured using an ELISA detecting IgG antibodies against a recombinant T. vaginalis α-actinin protein. Seropositivity to T. vaginalis was observed in 35 of 470 (7.4%) cases and 26 of 470 (5.5%) controls (unadjusted OR = 1.47, 95% CI 0.82-2.64; adjusted OR = 1.31, 95% CI 0.67-2.53). The association was similarly not significant when cases were confined to extraprostatic tumors having regional or distant spread (n = 121) regardless of grade (unadjusted OR = 1.37, 95% CI 0.63-3.01; adjusted OR = 1.20, 95% CI 0.46-3.11). The association of T. vaginalis with prostate cancer risk did not vary by aspirin use. Our findings do not support a role for T. vaginalis in the etiology of advanced prostate cancer.