[Show abstract][Hide abstract] ABSTRACT: Mammographic density (MD) is a quantitative trait, measurable in all women, and is among the strongest markers of breast cancer risk. The population-based epidemiology of MD has revealed genetic, lifestyle and societal/environmental determinants, but studies have largely been conducted in women with similar westernized lifestyles living in countries with high breast cancer incidence rates. To benefit from the heterogeneity in risk factors and their combinations worldwide, we created an International Consortium on Mammographic Density (ICMD) to pool individual-level epidemiological and MD data from general population studies worldwide. ICMD aims to characterize determinants of MD more precisely, and to evaluate whether they are consistent across populations worldwide. We included 11755 women, from 27 studies in 22 countries, on whom individual-level risk factor data were pooled and original mammographic images were re-read for ICMD to obtain standardized comparable MD data. In the present article, we present (i) the rationale for this consortium; (ii) characteristics of the studies and women included; and (iii) study methodology to obtain comparable MD data from original re-read films. We also highlight the risk factor heterogeneity captured by such an effort and, thus, the unique insight the pooled study promises to offer through wider exposure ranges, different confounding structures and enhanced power for sub-group analyses.
[Show abstract][Hide abstract] ABSTRACT: Purpose:
Several experimental studies showed that magnesium intake improved insulin resistance and glucose uptake in diabetes patients. However, epidemiological studies on the association between magnesium intake and diabetes risk have yielded inconsistent results. We investigated whether magnesium intake is related to the risk of developing diabetes in a population-based cohort study in Japan.
Study subjects were participants in the Takayama study. A total of 13,525 residents in Takayama City, Japan, responded to a self-administered questionnaire in 1992 and to a follow-up questionnaire seeking information about diabetes in 2002. Magnesium and other nutrient intakes were estimated from a validated food frequency questionnaire administered at the baseline.
During a follow-up of 10 years, 438 subjects reported diabetes newly diagnosed by physician. Compared with women in the low quartile of magnesium intake, women in the high quartile were at a significantly reduced risk of diabetes (HR 0.50; 95 % CI 0.30-0.84; P-trend 0.005) after adjustments for covariates. In men, there was no association between magnesium intake and the risk of diabetes.
These results suggest that diets with a high intake of magnesium may decrease the risk of diabetes in women.
No preview · Article · Dec 2015 · European Journal of Nutrition
[Show abstract][Hide abstract] ABSTRACT: Hyperuricaemia is an undisputed and highly predictive biomarker for cardiovascular risk. SLC17A1, expressed in the liver and kidneys, harbours potent candidate single nucleotide polymorphisms that decrease uric acid levels. Therefore, we examined SLC17A1 polymorphisms (rs1165196, rs1179086, and rs3757131), which might suppress cardiovascular risk factors and that are involved in liver functioning, via a large-scale pooled analysis of the Japanese general population in a cross-sectional study. Using data from the Japan Multi-Institutional Collaborative Cohort Study, we identified 1842 participants of both sexes, 35-69-years-old, having the requisite data, and analysed their SLC17A1 genotypes. In men, logistic regression analyses revealed that minor alleles in SLC17A1 polymorphisms (rs1165196 and rs3757131) were associated with a low-/high-density lipoprotein cholesterol ratio >2.0 (rs1165196: odds ratio [OR], 0.703; 95% confidence interval [CI], 0.536-0.922; rs3757131: OR, 0.658; 95% CI, 0.500-0.866), and with homocysteine levels of >10.0 nmol/mL (rs1165196: OR, 0.544; 95% CI, 0.374-0.792; rs3757131: OR, 0.509; 95% CI, 0.347-0.746). Therefore, these polymorphisms had dominant negative effects on cholesterol homeostasis and hyperhomocysteinaemia, in men, independent of alcohol consumption, physical activity, or daily energy and nutrition intake. Thus, genetic variants of SLC17A1 are potential biomarkers for altered cholesterol homeostasis and hyperhomocysteinaemia in Japanese men.
Full-text · Article · Nov 2015 · Scientific Reports
[Show abstract][Hide abstract] ABSTRACT: Background:
Few studies have assessed the associations between sleep duration and stroke subtypes. We examined whether sleep duration is associated with mortality from total stroke, ischemic stroke, and hemorrhagic stroke in a population-based cohort of Japanese men and women.
Subjects included 12 875 men and 15 021 women aged 35 years or older in 1992, who were followed until 2008. The outcome variable was stroke death (ischemic stroke, hemorrhagic stroke, and total stroke).
During follow-up, 611 stroke deaths (354 from ischemic stroke, 217 from hemorrhagic stroke, and 40 from undetermined stroke) were identified. Compared with 7 h of sleep, ≥9 h of sleep was significantly associated with an increased risk of total stroke and ischemic stroke mortality after controlling for covariates. Hazard ratios (HRs) and 95% confidence intervals (CIs) were 1.51 (95% CI, 1.16-1.97) and 1.65 (95% CI, 1.16-2.35) for total stroke mortality and ischemic stroke mortality, respectively. Short sleep duration (≤6 h of sleep) was associated with a decreased risk of mortality from total stroke (HR 0.77; 95% CI, 0.59-1.01), although this association was of borderline significance (P = 0.06). The trends for total stroke and ischemic stroke mortality were also significant (P < 0.0001 and P = 0.0002, respectively). There was a significant risk reduction of hemorrhagic stroke mortality for ≤6 h of sleep as compared with 7 h of sleep (HR 0.64; 95% CI, 0.42-0.98; P for trend = 0.08). The risk reduction was pronounced for men (HR 0.31; 95% CI, 0.16-0.64).
Data suggest that longer sleep duration is associated with increased mortality from total and ischemic stroke. Short sleep duration may be associated with a decreased risk of mortality from hemorrhagic stroke in men.
Preview · Article · Nov 2015 · Journal of Epidemiology
[Show abstract][Hide abstract] ABSTRACT: Background:
Epidemiological studies of the association between smoking exposure and dental caries are limited.
The purpose of this cross-sectional study was to examine the association between prenatal and postnatal secondhand smoke (SHS) exposure and the prevalence of dental caries in primary dentition in young Japanese children.
Study subjects were 6412 children aged 3 years. Information on exposure to maternal smoking during pregnancy and postnatal SHS exposure at home was collected via parent questionnaire. Children were classified as having dental caries if one or more primary teeth had decayed or had been filled.
Compared with never smoking during pregnancy, maternal smoking in the first trimester of pregnancy was significantly associated with an increased prevalence of dental caries in children (adjusted odds ratio=1.37, 95% confidence interval: 1.03-1.80). Postnatal SHS exposure was also positively associated with dental caries, with a significant positive exposure-response relationship. Compared with children not exposed to prenatal maternal smoking or postnatal SHS at home, those exposed to both prenatal and postnatal smoking had higher odds of dental caries (adjusted odds ratio=1.62, 95% confidence interval: 1.23-2.11).
Our findings suggest that maternal smoking during pregnancy and postnatal SHS exposure may be associated with an increased prevalence of dental caries in primary dentition.
No preview · Article · Oct 2015 · Environmental Research
[Show abstract][Hide abstract] ABSTRACT: Objective
The association between vegetable consumption and colorectal cancer risk remains unclear and may differ by region. We performed a systematic review and meta-analysis of epidemiologic studies on this issue among the Japanese population.
A systematic review and meta-analysis was performed by searching MEDLINE through PubMed and the Ichushi database for cohort and case–control studies that were published by the end of December 2014. Associations were evaluated based on their magnitude and the strength of the evidence. Meta-analysis was performed by using the random effects model to estimate the summary relative risk with 95% confidence interval according to the study design. The final judgment was made based on a consensus of the research group members with consideration for both epidemiological evidence and biological plausibility.
We identified six cohort studies and 11 case–control studies on vegetable intake and colorectal cancer among the Japanese population. Of the cohort studies, one study showed a weak inverse association with colon cancer and another study showed a weak positive association with rectal cancer in men, but other studies found no associations between vegetable consumption and colon and rectal cancers. With regard to case–control studies, one study found a strong inverse association with colon cancer, and three studies showed a weak-to-strong inverse association with rectal cancer. In meta-analysis, the summary relative risk (95% confidence interval) for the highest vs. the lowest categories of vegetable consumption were 1.00 (0.92–1.10) and 0.75 (0.59–0.96) for cohort and case–control studies, respectively.
There was insufficient evidence to support an association between intake of vegetables and the risk of colorectal cancer among the Japanese population.
No preview · Article · Oct 2015 · Japanese Journal of Clinical Oncology
[Show abstract][Hide abstract] ABSTRACT: Background Mammographic density (MD) is a strong intermediate risk factor for breast cancer (BC) and, having both genetic and environmental determinants, may account for the over 6-fold international variations in BC incidence rates. The International Pooling Project of Mammographic Density is a worldwide collaborative project of MD targeting populations spanning the BC incidence range. The aims of the project are to (i) describe international variations in overall and age-specific distributions of MD, (ii) assess whether international variations in MD are explained by variations in the distributions of individual-level determinants of this marker and (iii) examine whether international variations in MD correlate with corresponding BC incidence rates.
Methods Each contributing study provided comparable data on MD risk factors and mammographic images from a random sample of ˜ 400 general population women, who had undergone screening mammography. Images were transferred in digitised screen-film, full-field or computed radiography digital DICOM format (raw or processed). Images were randomly allocated into batches for MD reading using the Cumulus 6 thresholding software, by experienced readers who were blinded to study and individual-level factors. Data on MD determinants were pooled and linked with MD readings. Results are calibrated according to type of digital image (raw to processed), and adjusted for image type.
Results 22 countries and approximately 12,000 women are included, spanning populations with age-standardised BC incidence rates (ASR) of 25.8 (India) to 99 (The Netherlands) per 100,000 woman-years. To date, for 9,635 participants data have been pooled (results will be updated). The MD risk factors vary greatly across populations, for example: mean age at menarche (in years) was 14.3 (95% CI 14.1–14.5) in Korean women and 12.6 (12.5–12.8) in Mexican women; mean parity was 3.8 (3.6–4.1) in Egyptian women and 1.3 (1.1–1.4) in those from Hong Kong; and mean BMI (in kg/m2) was 33.7 (33.1–34.3) in Egyptian women compared to 22.3 (21.6–22.9) in those from India. Differences in MD according to these distributions will be presented.
Discussion The international perspective of this study generated large exposure heterogeneity enabling a wider investigation of MD determinants and the extent to which MD is an intermediate marker of BC risk, both within and between populations.
Full-text · Article · Sep 2015 · Journal of Epidemiology & Community Health
[Show abstract][Hide abstract] ABSTRACT: Objective:
Extraovarian sex hormone production plays an important role in estrogen biosynthesis in postmenopausal women. We examined possible associations between serum sex hormone level and polymorphisms in CYP19A1, HSD17B1, and HSD17B2. We also assessed possible interaction between these polymorphisms and current overweight.
We conducted a cross-sectional study. 785 Japanese natural postmenopausal women were randomly selected from the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study database. Information on lifestyle factors was obtained from a self-administered questionnaire. Serum estrogens and androgens levels were measured by liquid chromatography-tandem mass spectrometry. Four tag SNPs (single nucleotide polymorphisms) of CYP19A1, one missense SNP of HSD17B1 and three tag SNPs of HSD17B2 were examined by Invader assay. A trend test was conducted using linear regression.
After adjustment for multiple comparisons, we found that rs4441215 and rs936306 in CYP19A1 and rs4888202 and rs2955160 in HSD17B2 were associated with differences in serum estrone level. Further, rs4441215 and rs936306 were associated with differences in serum estradiol level. None of these polymorphisms showed a significant interaction with current body mass index (BMI).
Our findings suggested that CYP19A1 and HSD17B2 polymorphisms might be associated with circulating sex hormone levels in Japanese postmenopausal women, independent of current BMI.
[Show abstract][Hide abstract] ABSTRACT: Objective
To evaluate the effect of a previous indication of hyperglycemia or previous diagnosis of diabetes on quality of life (QOL) in a randomly selected population from Gifu City, Japan.
In total, 452 males and 648 females were enrolled in this study. We collected information on previous indications of hyperglycemia and previous diagnoses of diabetes using a self-reported questionnaire. Participants also completed the World Health Organization Quality of Life-26 (WHOQOL-26) questionnaire and provided blood samples for the measurement of fasting plasma glucose and glycated hemoglobin levels. A 75-g oral glucose tolerance test was also performed. We compared QOL scores between the previous indication of hyperglycemia group and previous diagnosis of the diabetes group to those of the control group.
WHOQOL-26 scores were significantly lower in the previous diagnosis of diabetes group than in the control group (3.23 ± 0.43 vs. 3.45 ± 0.43; p < 0.01). However, WHOQOL-26 scores in the previous indication of hyperglycemia group were not significantly different from those of the control group. Lowering of WHOQOL-26 scores was significantly affected by the previous diagnosis of diabetes not by the plasma glucose levels.
Our study suggests that a previous diagnosis of diabetes has a negative effect on QOL in a Japanese population. Health promotion and education that take QOL into account should be considered for people diagnosed with diabetes.
No preview · Article · Jul 2015 · Diabetology International
[Show abstract][Hide abstract] ABSTRACT: International reviews have concluded that consumption of fruit and vegetables might decrease the risk of lung cancer. However, the relevant epidemiological evidence still remains insufficient in Japan. Therefore, we performed a pooled analysis of data from four population-based cohort studies in Japan with >200,000 participants and >1,700 lung cancer cases. We computed study-specific hazard ratios by quintiles of vegetable and fruit consumption as assessed by food frequency questionnaires. Summary hazard ratios were estimated by pooling the study-specific hazard ratios with a fixed-effect model. In men, we found inverse associations between fruit consumption and the age- and area-adjusted risk of mortality or incidence of lung cancer. However, the associations were largely attenuated after adjustment for smoking and energy intake. The significant decrease in risk among men remained only for a moderate level of fruit consumption; the lowest summary hazard ratios were found in the third quintile of intake (mortality: 0.71, 95% confidence interval 0.60-0.84; incidence: 0.83, 95% confidence interval 0.70-0.98). This decrease in risk was mainly detected in ever smokers. Conversely, vegetable intake was positively correlated with the risk of incidence of lung cancer after adjustment for smoking and energy intake in men (trend P, 0.024); the summary hazard ratio for the highest quintile was 1.26 (95% confidence interval 1.05-1.50). However, a similar association was not detected for mortality from lung cancer. In conclusion, a moderate level of fruit consumption is associated with a decreased risk of lung cancer in men among the Japanese population. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: Mammographic density, i.e., the radiographic appearance of the breast, is a strong predictor of breast cancer risk. To determine whether the association of breast density with breast cancer is modified by a first-degree family history of breast cancer (FHBC) in women of white and Asian ancestry, we analyzed data from four case-control studies conducted in the USA and Japan.
The study population included 1,699 breast cancer cases and 2,422 controls, of whom 45 % reported white (N = 1,849) and 40 % Asian (N = 1,633) ancestry. To standardize mammographic density assessment, a single observer re-read all mammograms using one type of interactive thresholding software. Logistic regression was applied to estimate odds ratios (OR) while adjusting for confounders.
Overall, 496 (12 %) of participants reported a FHBC, which was significantly associated with breast cancer risk in the adjusted model (OR 1.51; 95 % CI 1.23-1.84). There was a statistically significant interaction on a multiplicative scale between FHBC and continuous percent density (per 10 % density: p = 0.03). The OR per 10 % increase in percent density was higher among women with a FHBC (OR 1.30; 95 % CI 1.13-1.49) than among those without a FHBC (OR 1.14; 1.09-1.20). This pattern was apparent in whites and Asians. The respective ORs were 1.45 (95 % CI 1.17-1.80) versus 1.22 (95 % CI 1.14-1.32) in whites, whereas the values in Asians were only 1.24 (95 % CI 0.97-1.58) versus 1.09 (95 % CI 1.00-1.19).
These findings support the hypothesis that women with a FHBC appear to have a higher risk of breast cancer associated with percent mammographic density than women without a FHBC.
No preview · Article · Mar 2015 · Cancer Causes and Control
[Show abstract][Hide abstract] ABSTRACT: The effects of smoking on breast cancer remain unclear. We assessed the associations of subject's or husband's smoking status with breast cancer incidence in a population-based prospective study in Japan. Subjects were 15,719 women aged 35 years or older. The follow-up was conducted from September, 1992 to March, 2008. Cancer incidence was mainly confirmed through regional population-based cancer registries. Breast cancer was defined as code C50 according to ICD-10. Lifestyles, including smoking status, were assessed with a self-administered questionnaire. Alcohol consumption was assessed with a validated food-frequency questionnaire. After multivariate adjustments for age, body mass index, alcohol consumption, physical activity, education, age at menarche, age at first delivery, menopausal status, number of children, and history of hormone replacement therapy, active smoking was not associated with the risk of breast cancer. Compared with never smokers whose husbands had never smoked, the risks of breast cancer were 1.98 (95% CI: 1.03 - 3.84) among never smokers whose husband was current smoker of 21 cigarettes per day or more. The increased risk of breast cancer among women having a smoking husband was pronounced among those who did not habitually consume alcohol. These results suggest that exposure to smoke from husband is a potential risk factor for breast cancer. The implication of alcohol drinking for the increased breast cancer risk from passive smoking is needed to be addressed in further studies.This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: Although several experimental studies suggested that soy isoflavone intake inhibits the growth of stomach cancer, previous epidemiological studies have observed inconsistent results. We evaluated the associations of soy or isoflavone intake with stomach cancer incidence after considering several lifestyle factors, including salt intake, in a population-based prospective cohort study in Japan. Subjects were 14,219 men and 16,573 women aged 35 years or older in September 1992. Soy and isoflavone intakes, assessed with a validated food-frequency questionnaire, were controlled for the total energy intake. Cancer incidence was mainly confirmed through regional population-based cancer registries. Until March 2008, 441 men and 237 women developed stomach cancer. After adjustments for multiple confounders, a significantly decreased relative risk of stomach cancer was observed in the highest vs. lowest quartile of soy intake; the estimated hazard ratios were 0.71 (95% CI: 0.53, 0.96) for men (p for trend=0.039), and 0.58 (95% CI: 0.36, 0.94) for women (p for trend=0.003). Similar inverse associations between isoflavone intake and stomach cancer risk were also observed in women. Higher intake of non-fermented soy foods was significantly associated with a lower risk of stomach cancer (p for trend: 0.022 in men and 0.005 in women), whereas there was no significant association between the intake of fermented soy foods and a risk of stomach cancer. These results suggest that a high intake of soy isoflavone, mainly non-fermented soy foods, have a protective effect against stomach cancer. This article is protected by copyright. All rights reserved.
No preview · Article · Jan 2015 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Background: It has been hypothesized that alteration of hormone systems is involved in the carcinogenesis of acrylamide. The aim of the present study was to examine the cross-sectional associations between dietary acrylamide intake and sex hormone levels in premenopausal Japanese women. Methods: Study subjects were 393 women who had regular menstrual cycles less than 40 days long. Acrylamide intake was assessed with a food-frequency questionnaire and was based on acrylamide concentration reported from analyses of Japanese foods. We measured the plasma concentrations of estradiol, testosterone, dehydroepiandrosterone sulfate, sex hormone-binding globulin, follicle-stimulating hormone, luteinizing hormone, and prolactin. Results: After controlling for age, the phase of the menstrual cycle, and other covariates, acrylamide intake was statistically significantly inversely associated with total and free estradiol levels and statistically significantly positively associated with follicle-stimulating hormone level. Total and free estradiol levels were 18.2% and 19.3% lower, respectively, in women in the highest quartile of acrylamide intake than in those in the lowest quartile of intake. Follicle-stimulating hormone levels were 23.5% higher in women in the highest quartile of acrylamide intake than in those in the lowest quartile of intake. Conclusion: The data suggest that acrylamide intake may alter estradiol and follicle-stimulating hormone levels. Impact: High estradiol levels have been associated with an increased risk of breast cancer. Although the results need confirmation, they highlight the need to investigate the relationships among dietary acrylamide, sex hormones, and breast cancer risk.
No preview · Article · Oct 2014 · Cancer Epidemiology Biomarkers & Prevention
[Show abstract][Hide abstract] ABSTRACT: Aim
Several studies have suggested that cigarette-smoking affects insulin sensitivity in Western populations. The present study evaluated glucose tolerance, pancreatic β-cell function and insulin sensitivity in relation to active and passive smoking among the Japanese.
A total of 411 men and 586 women were recruited into a community-based cross-sectional study in Gifu, Japan. Diabetes, impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) were screened for by a 75 g oral glucose tolerance test. HOMA and insulinogenic (ΔI0−30/ΔG0−30) indexes were used to estimate insulin secretion and sensitivity. To assess the possible association of self-reported smoking status and parameters of glucose metabolism, logistic regression was applied after adjusting for potential confounders.
Currently smoking women were more likely to have diabetes, IGT or IFG compared with never-smoking women (OR: 2.26, 95% CI: 1.05–4.84). Heavy-smoking men (≥ 25 cigarettes/day) were likely to be in the lowest tertile group of ΔI0–30/ΔG0–30 compared with never-smoking men (OR: 2.64, 95% CI: 1.05–6.68, Ptrend = 0.04). The number of cigarettes/day was borderline significantly associated with diabetes in men. Also with borderline significance, never-smoking women with smoking husbands were more likely to have diabetes, IGT or IFG (OR: 1.62, 95% CI: 1.00–2.62) and significantly more likely to have lower HOMA-β (OR: 2.17, 95% CI: 1.36–3.48) than those without smoking husbands.
The greater the number of cigarettes smoked per day appears to be associated with diabetes among men whereas, among women, both active and passive smoking appear to be associated with diabetic states, including IGT and IFG. An association between smoking status and insulin secretion is also suggested, whereas no significant association was observed with HOMA-IR in this Japanese subjects, suggesting that the influence of smoking on glucose metabolism may differ among races.
No preview · Article · Oct 2014 · Diabetes & Metabolism
[Show abstract][Hide abstract] ABSTRACT: Diets with a high glycaemic index (GI) or glycaemic load (GL) have been hypothesised to increase the risk of diabetes, CVD and some cancers. In the present study, the associations of dietary GI and GL with the risk of all-cause and cause-specific mortality were prospectively examined in a general population in Japan, where white rice is the main contributor of dietary GI and GL. A total of 28 356 residents of Takayama City, Japan, who responded to a self-administered questionnaire in 1992 were included in the present analyses. Dietary intake was assessed using a validated FFQ. Mortality was ascertained over 16 years. In men, dietary GI was found to be significantly inversely associated with the risk of all-cause and non-cancer, non-cardiovascular mortality; the hazard ratios (HR) for the highest v. lowest quartile were 0·80 (95 % CI 0·68, 0·95) and 0·64 (95 % CI 0·49, 0·84), respectively. Dietary GL was found to be significantly inversely associated with the risk of all-cause, cancer, and non-cancer, non-cardiovascular mortality; the HR for the highest v. lowest quartile were 0·71 (95 % CI 0·59, 0·86), 0·71 (95 % CI 0·52, 0·99) and 0·64 (95 % CI 0·48, 0·87), respectively. The results obtained for the GL derived from white rice, but not from other foods, closely mirrored those obtained for overall GL. In women, dietary GI was found to be significantly positively associated with the risk of cardiovascular mortality; the HR for the highest v. lowest quartile was 1·56 (95 % CI 1·15, 2·13). The results of the present study suggest potential favourable effects of dietary GI and GL on mortality in men, but an association between high GI and an increased risk of cardiovascular mortality in women.
No preview · Article · Oct 2014 · British Journal Of Nutrition