Purpose
The association between high mammographic density (MD) and elevated breast cancer risk is well established. However, the role of absolute non-dense area remains unclear. We estimated the ...effect of the mammographic non-dense area and other density parameters on the risk of breast cancer.
Methods
This study utilizes data from a population-based case–control study conducted in Greater Vancouver, British Columbia, with 477 female postmenopausal breast cancer cases and 588 female postmenopausal controls. MD measures were determined from digitized screening mammograms using computer-assisted software (Cumulus). Marginal odds ratios were estimated by inverse-probability weighting using a causal diagram for confounder selection. Akaike information criteria and receiver operating characteristic curves were used to assess the goodness of fit and predictive power of unconditional logistic models containing MD parameters.
Results
The risk of breast cancer is 60% lower for the highest quartile compared to the lowest quartile of mammographic non-dense area (marginal OR 0.40, 95% CI 0.26–0.61,
p
-trend < 0.001). The cancer risk almost doubles for the highest quartile compared to the lowest quartile of dense area (marginal OR 1.81, 95% CI 1.19–2.43,
p
-trend < 0.001). For the highest quartile of percent density, breast cancer risk was more than three times higher than for the lowest quartile (marginal OR 3.15, 95% CI 1.90–4.40,
p
-trend < 0.001). No difference was seen in predictive accuracy between models using percent density alone, dense area alone, or non-dense area plus dense area.
Conclusions
In this study, non-dense area is an independent risk factor after adjustment for dense area and other covariates, inversely related with the risk of breast cancer. However, non-dense area does not improve prediction over that offered by percent density or dense area alone.
Wild fish from Qiandao Hu, a reservoir in the Zhejiang Province in eastern China, have increased mercury (Hg) concentrations exceeding the World Health Organization’s (WHO) recommended guidelines. ...Due to the importance of freshwater biota in the local cuisine, dietary exposure to increased neurotoxic Hg is a concern in this region. An environmental hair-marker study was undertaken coincident with a cross-sectional epidemiologic study with 50 women age 17–46 years living in a Qiandao Hu fishing village. Diet, occupation, and other possible sources of Hg were recorded by way of questionnaires. Total mercury (THg) and selenium (Se) concentrations were measured in human hair samples and in important market fish species. Fish THg and Se concentrations were increased, with some fish concentrations >200 ng/g THg and 500 ng/g Se (wet weight ww). However, the average hair THg was low at 0.76 ± 0.51 μg/g dry weight, lower than the WHO’s no observable–adverse effect level (50 μg/g), whereas the average hair Se was 1.0 μg/g. Hair THg concentration was positively associated with the average mass of fish consumed weekly, indicating that fish consumption is the main contributor to hair THg in this geographic area. The age-related hair THg trend was not linear but instead demonstrated a rapid increase in THg before age 25 years, followed by consistent concentrations in all ages after age 25 years. There was a positive correlation (
p
< 0.001) between molar Se and Hg in the hair samples, suggesting a possible antagonistic relation. This is the first study examining the relation between dietary Hg exposure and hair THg in an eastern China community where freshwater fish, as opposed to marine fish, dominates the cuisine.
ObjectivesThere is limited research on the association between sedentary behaviour and breast cancer risk, particularly whether sedentary behaviour is differentially associated with premenopausal and ...postmenopausal breast cancer. We pooled data from 2 case–control studies from Australia and Canada to investigate this association.MethodsThis pooled analysis included 1762 incident breast cancer cases and 2532 controls. Participants in both studies completed a lifetime occupational history and self-rated occupational physical activity level. A job-exposure matrix (JEM) was also applied to job titles to assess sedentary work. Logistic regression analyses (6 pooled and 12 study-specific) were conducted to estimate associations between both self-reported and JEM-assessed sedentary work and breast cancer risk among premenopausal and postmenopausal women.ResultsNo association was observed in the 6 pooled analyses, and 10 of the study-specific analyses also showed null results. 2 study-specific analyses provided inconsistent and contradictory results, with 1 showing statistically significant increased risk of breast cancer for self-reported sedentary work among premenopausal women cancer in the Canadian study, and the other a non-significant inverse association between JEM-assessed sedentary work and breast cancer risk among postmenopausal women in the Australian study.ConclusionsWhile a suggestion of increased risk was seen for premenopausal women in the Canadian study when using the self-reported measure, overall this pooled study does not provide evidence that sedentary work is associated with breast cancer risk.
This study describes the association between unemployment and cause-specific mortality for a cohort of working-age Canadians.
We conducted a cohort study over an 11-year period among a broadly ...representative 15% sample of the non-institutionalized population of Canada aged 30-69 at cohort inception in 1991 (888,000 men and 711,600 women who were occupationally active). We used cox proportional hazard models, for six cause of death categories, two consecutive multi-year periods and four age groups, to estimate mortality hazard ratios comparing unemployed to employed men and women.
For persons unemployed at cohort inception, the age-adjusted hazard ratio for all-cause mortality was 1.37 for men (95% confidence interval (CI): 1.32-1.41) and 1.27 for women (95% CI: 1.20-1.35). The age-adjusted hazard ratio for unemployed men and women was elevated for all six causes of death: malignant neoplasms, circulatory diseases, respiratory diseases, alcohol-related diseases, accidents and violence, and all other causes. For unemployed men and women, hazard ratios for all-cause mortality were equivalently elevated in 1991-1996 and 1997-2001. For both men and women, the mortality hazard ratio associated with unemployment attenuated with age.
Consistent with results reported from other long-duration cohort studies, unemployed men and women in this cohort had an elevated risk of mortality for accidents and violence, as well as for chronic diseases. The persistence of elevated mortality risks over two consecutive multi-year periods suggests that exposure to unemployment in 1991 may have marked persons at risk of cumulative socioeconomic hardship.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objective:
To describe the association between occupation and risk of suicide among working-age men and women in Canada.
Method:
This study of suicide mortality over an 11-year period is based on a ...broadly representative 15% sample of the noninstitutionalized population of Canada aged 30 to 69 years at cohort inception. Age-standardized mortality rates (ASMRs) and rate ratios were calculated for men and women in 5 categories of skill level and 80 specific occupational groups, as well as for people not occupationally active.
Results:
The suicide mortality rate was 20.1/100 000 person years for occupationally active men (during 9 600 000 person years of follow-up) and 5.3/100 000 person years for occupationally active women (during 8 100 000 person years of follow-up). Among occupationally active men, elevated rates of suicide mortality were observed for 9 occupational groups and protective effects were observed for 6 occupational groups. Among women, elevated rates of suicide were observed in 4 occupational groups and no protective effects were observed. For men and women, ASMRs for suicide were inversely related to skill level.
Conclusions:
The limited number of associations between occupational groups and suicide risk observed in this study suggests that, with few exceptions, the characteristics of specific occupations do not substantially influence the risk for suicide. There was a moderate gradient in suicide mortality risk relative to occupational skill level. Suicide prevention strategies in occupational settings should continue to emphasize efforts to restrict and limit access to lethal means, one of the few suicide prevention policies with proven effectiveness.
Purpose: Physical activity reduces breast cancer risk, although most evidence is for activity in the moderate-to-vigorous intensity range. The effect of light intensity physical activity (LIPA) is ...unknown. We aimed to determine the association between self-reported lifetime LIPA and pre- and post-menopausal breast cancer risk. Our secondary objective was to analyze risk stratified by estrogen and progesterone tumor receptor status. Methods: Data were from a case–control study of 1,110 incident breast cancer cases (388 pre-menopausal; 722 postmenopausal) and 1,172 controls (442 pre-menopausal; 730 post-menopausal) recruited at two Canadian sites. Lifetime leisure-time, household, and occupational physical activity and covariates were assessed by questionnaire. Mean minutes per day of LIPA for each of the age periods 12–17, 18–34, 35–49, ≥50, and the total lifetime were calculated. Odds ratios were calculated using unconditional logistic regression for overall breast cancer risk and using polytomous logistic regression for estrogen receptor (ER)/progesterone receptor (PR)-defined tumor subtypes and were adjusted for moderateto-vigorous physical activity and other confounders. Results: LIPA was not associated with breast cancer risk at any age period across the life course: odds ratio (OR) = 0.81; 95 % CI 0.53–1.24 for pre-menopausal women and OR = 0.87; 95 % CI 0.64–1.19 for post-menopausal women in the highest vs. lowest categories of total lifetime LIPA. No heterogeneity in risk by ER/PR tumor status was observed. Conclusions: Our results suggest that light intensity physical activity is not associated with breast cancer risk reduction. This finding is important for physical activity recommendations for breast cancer prevention.
In 2011, the U.S. Institute of Medicine updated the definition of vitamin D inadequacy to serum 25-hydroxyvitamin D (25(OH)D) concentration of 30-<50 nmol/l and of deficiency to serum 25(OH)D < 30 ...nmol/l. We describe the prevalence of these conditions according to these definitions, seasonal variation in 25(OH)D and predictors of serum 25(OH)D concentrations among working, white women.
Participants recorded lifestyle factors and dietary intake and provided fasting blood samples for measurement of serum 25(OH)D in both summer and winter. Predictors of serum 25(OH)D variation were analysed using linear regression and generalized linear mixed models.
Kingston General Hospital in Kingston, Ontario, Canada, from April 2008 to July 2009.
Female premenopausal nurses (n 83) working full-time rotating shifts.
Deficient or inadequate vitamin D status was observed in 9% of participants following summer/autumn and in 13% following winter/spring. Predictors of serum 25(OH)D concentration were vitamin D supplement use, tanning bed use and season. Tanning bed use increased serum 25(OH)D by 23.24 nmol/l (95% CI 8.78, 37.69 nmol/l, P = 0.002) on average.
According to the 2011 Institute of Medicine bone health guidelines, over 10% of nurses had deficient or inadequate vitamin D status following winter. Higher serum concentrations were associated with use of tanning beds and vitamin D supplements. As health promotion campaigns and legal restrictions are successful in reducing tanning bed use among women, our data suggest that increased prevalence of vitamin D inadequacy and deficiency may be a consequence, and that low vitamin D status will need to be countered with supplementation.
Background
Human leukocyte antigen (HLA) genes play critical roles in immune surveillance, an important defence against tumors. Imputing HLA genotypes from existing single-nucleotide polymorphism ...datasets is low-cost and efficient. We investigate the relevance of the major histocompatibility complex region in breast cancer susceptibility, using imputed class I and II HLA alleles, in 25,484 women of Asian ancestry.
Methods
A total of 12,901 breast cancer cases and 12,583 controls from 12 case–control studies were included in our pooled analysis. HLA imputation was performed using SNP2HLA on 10,886 quality-controlled variants within the 15–55 Mb region on chromosome 6. HLA alleles (
n
= 175) with info scores greater than 0.8 and frequencies greater than 0.01 were included (resolution at two-digit level: 71; four-digit level: 104). We studied the associations between HLA alleles and breast cancer risk using logistic regression, adjusting for population structure and age. Associations between HLA alleles and the risk of subtypes of breast cancer (ER-positive, ER-negative, HER2-positive, HER2-negative, early-stage, and late-stage) were examined.
Results
We did not observe associations between any HLA allele and breast cancer risk at
P
< 5e−8; the smallest p value was observed for HLA-C*12:03 (OR = 1.29,
P
= 1.08e−3). Ninety-five percent of the effect sizes (OR) observed were between 0.90 and 1.23. Similar results were observed when different subtypes of breast cancer were studied (95% of ORs were between 0.85 and 1.18).
Conclusions
No imputed HLA allele was associated with breast cancer risk in our large Asian study. Direct measurement of HLA gene expressions may be required to further explore the associations between HLA genes and breast cancer risk.
DNA repair variants and breast cancer risk Grundy, Anne; Richardson, Harriet; Schuetz, Johanna M. ...
Environmental and molecular mutagenesis,
05/2016, Letnik:
57, Številka:
4
Journal Article
Objective: To determine the effect of physical activity and sedentary behavior on melatonin levels in a group of rotating shift nurses. Methods: Physical activity and sedentary behaviors for 118 ...nurses were recorded during both a day shift and a night shift using activity diaries, and concentrations of urinary 6-sulfatoxymelatonin were analyzed for each shift. Results: During the day shift, energy expended in moderate- and vigorous-intensity physical activity between 3 pm and 7 am was negatively associated with melatonin levels (P = 0.024). During the night shift, energy expended in sedentary behaviors was negatively associated with melatonin levels (P = 0.008). Conclusions: Physical activity and energy expended in sedentary behavior are inversely associated with morning urinary melatonin concentrations. Nevertheless, energy expenditure explains a relatively small amount of melatonin variation, perhaps suggesting that peak melatonin is minimally affected by these patterns of physical activity.
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