Sleep duration and breast cancer risk: A meta‐analysis of observational studies

Studies on the association of short or long sleep duration with breast cancer risk have reported inconsistent results. We quantitatively assessed this association by conducting a meta‐analysis based on the evidence from observational studies. In April 2013, we performed electronic searches in PubMed, EmBase and the Cochrane Library to identify studies examining the effect of sleep duration on breast cancer incidence. The odds ratio (OR) was used to measure any such association in a random‐effects model. The analysis was further stratified by confounding factors that could bias the results. A total of six studies (two case–control and four cohort studies) involving 159,837 individuals were included in our meta‐analysis. Our study did not show an association between either short or long sleep duration and breast cancer risk (short sleep duration data: pooled OR = 1.01, 95% confidence interval (CI) = 0.90–1.14, p = 0.853; long sleep duration data: pooled OR = 0.95, 95% CI = 0.86–1.04, p = 0.251). Moreover, we did not identify any statistically significant association between sleep duration and breast cancer risk in all the subgroup analyses. In conclusion, our findings indicate that sleep duration has no effect on breast cancer risk.     

Sleep duration and the risk of breast cancer: the Ohsaki Cohort Study

In a prospective study of 23 995 Japanese women, short sleep duration was associated with higher risk of breast cancer (143 cases), compared with women who slept 7 h per day, the multivariate hazard ratio of those who slept 相似文献   

夜间睡眠时间与女性乳腺癌发病风险的前瞻性队列研究

目的 我国女性乳腺癌发病率逐年上升,夜间睡眠时间长短可能与一系列健康效应相关,为探究夜间睡眠时间与乳腺癌发病关联性,本研究以唐山开滦集团前瞻性动态队列中的女性人群为基础进行了相关分析.方法 采用2006-2011年开滦集团体检人群中女性人群资料,收集社会人口学资料、睡眠习惯、身高、体质量等基线信息及乳腺癌发病结局信息.采用Cox比例风险回归模型分析夜间睡眠时间与女性乳腺癌发病风险的关联性.结果 共纳入24 692名女性体检者,总随访108 029.22人年,平均随访时间为4.38年,新发乳腺癌病例107例.以夜间睡眠7h为参比组,单因素分析提示夜间睡眠偏短(≤6h,HR=0.99,95％CI=0.52～1.87)或偏长(≥8h,HR=0.84,95％CI=0.49～1.45)与乳腺癌发病风险无统计学关联.调整年龄、受教育程度、饮酒等混杂因素后,分析仍显示夜间睡眠时间偏短(HR=0.82,95％CI=0.43～1.56)或偏长(HR=0.94,95％CI=0.54～1.64)与女性乳腺癌的发病无统计学关联.按年龄、打鼾情况和BMI分层分析及敏感性分析后,结果仍未发现存在显著性关联.结论 本研究结果尚不支持夜间睡眠时间偏短或偏长与女性乳腺癌的发病风险存在关联性.     

Calcium intake is not related to breast cancer risk among Singapore Chinese women

There is experimental evidence that calcium protects against breast cancer development. Prospective epidemiologic studies supporting a protective effect of calcium on breast cancer risk have mainly been limited to Western populations. We examined the association between calcium intake and breast cancer risk in the Singapore Chinese Health Study, a large population‐based prospective cohort. Calcium intake and supplement use was assessed by in‐person interviewer using a validated food frequency questionnaire. After a mean follow‐up of 14.2±3.5 years, 823 cohort participants developed invasive breast cancer. Multivariate proportional hazards regression models were fitted to examine the associations between calcium intake and breast cancer risk. Vegetables were the primary food source of calcium in this study population, followed by dairy products, grains and soy foods. Calcium intake was not associated with breast cancer risk, comparing highest quartile (>345.6 mg/1,000 kcal/day) to lowest quartile (<204.5 mg/1,000 kcal/day) of intake. There was no evidence of effect modification by menopausal status, body mass index, dietary vitamin D or stage of disease at diagnosis. Our findings do not support a hypothesis for calcium in breast cancer chemoprevention, contrary to findings from previous studies among Western populations with higher calcium intake primarily from dairy products and supplements.     

Sleep duration and the risk of prostate cancer: the Ohsaki Cohort Study

In a prospective study of prostate cancer incidence (127 cases), among 22 320 Japanese men, sleep duration was associated with lower risk; the multivariate hazard ratio of men who slept >or=9 h per day compared with those who slept less was 0.48 (95% confidence interval: 0.29-0.79, P for trend=0.02).     

Sleep duration and breast cancer risk in the Breast Cancer Detection Demonstration Project follow-up cohort

Background:

Short sleep has been hypothesised to increase the risk of breast cancer. However, little is known about the association between sleep and different subtypes of breast cancer defined by hormone receptor status.

Methods:

Among 40 013 women in the Breast Cancer Detection Demonstration Project, including 1846 incident breast cancer cases, we prospectively examined self-reported weekday and weekend sleep duration in relation to breast cancer risk. We used multivariate Cox proportional hazards regression models to estimate relative risks (RRs) and 95% confidence intervals (CIs).

Results:

We found no association between sleep and overall breast cancer. However, we observed a decreased risk of ER+PR+ breast cancer (RR _{<6 vs 8 – 9 h} (95% CI): 0.54 (0.31, 0.93), P for trend, 0.003) with shorter sleep duration.

Conclusions:

Our finding does not support an association between sleep duration and overall breast cancer risk. However, the effect of sleep on different subtypes of breast cancer deserves further investigation.     

Sleep dysfunction and psychosocial adaptation among women undergoing treatment for non‐metastatic breast cancer

Objective: The current study aimed to determine the frequency of sleep disturbances in women prior to adjuvant therapy for breast cancer (BCa), and whether greater sleep dysfunction uniquely predicts poorer functional outcomes. Method: We assessed subjective sleep reports and associated them with multiple indicators of psychosocial adaptation in 240 women with Stage I–III BCa before they had begun adjuvant treatment. Results: The average global score on the Pittsburgh Sleep Quality Index (PSQI) was 8.49 (SD=4.16); 54% scoring above the suggested adjusted cutoff for cancer populations of 8.0. Controlling for various medical, sociodemographic, and psychosocial covariates, multiple regression analyses revealed that higher global PSQI score was significantly associated with poorer functional well‐being, greater fatigue intensity, greater disruptions in social interactions, and lower positive states of mind. Specifically, a poorer ‘sleep efficiency’ PSQI component was associated with poorer functional quality of life and the SIP–Social Interactions subscale, while a poorer ‘sleep quality’ (SQ) PSQI component was associated with all of the outcomes except for the SIP–Recreations and Pastimes subscale. Conclusions: Results indicate consistent associations between a clinical indicator of sleep dysfunction, particularly those subscales of the PSQI comprising the ‘SQ’ component, and multiple indicators of psychosocial adaptation among women treated for BCa, independent of anxiety and depression, and suggest the value of comprehensive psychosocial interventions that consider sleep problems. Copyright © 2009 John Wiley & Sons, Ltd.     

Urinary endogenous sex hormone levels and the risk of postmenopausal breast cancer

To assess the relation between urinary endogenous sex steroid levels and the risk of postmenopausal breast cancer, a nested case-cohort study was conducted within a large cohort (the DOM cohort) in the Netherlands (n=9,349). Until the end of follow-up (1 January 1996), 397 postmenopausal breast cancer cases were identified and a subcohort of 424 women was then taken from all eligible women. Women using hormones were excluded, leaving 364 breast cancer cases and 382 women in the subcohort for the analyses. Concentrations of oestrone, oestradiol, testosterone, 5alpha-androstane-3alpha, 17beta-diol and creatinine were measured in first morning urine samples, which had been stored since enrolment at -20 degrees C. A Cox proportional Hazards model was used, with Barlow's adjustment for case-cohort sampling, to estimate breast cancer risk in quartiles of each of the, creatinine corrected, hormone levels, the lowest quartile being the reference group. Women with higher levels of all four of the hormones were at increased risk for postmenopausal breast cancer (highest vs lowest quartile: incidence rate ratio for oestrone (IRR(oestrone)=2.5, 95% CI: 1.6-3.8; IRR(oestradiol)=1.5, 95% CI: 1.0-2.3; IRR(testosterone)=1.6, 95% CI: 1.0-2.4; IRR(5alpha-androstane-3alpha, 17beta-diol)=1.7, 95% CI: 1.1-2.7). In conclusion, women with higher excretion levels of both oestrogens and androgens have an increased risk of breast cancer.     

Dietary intakes of ω‐6 and ω‐3 polyunsaturated fatty acids and the risk of breast cancer

Experimental studies suggest detrimental effects of ω‐6 polyunsaturated fatty acids (PUFA), and beneficial effects of ω‐3 PUFAs on mammary carcinogenesis, possibly in interaction with antioxidants. However, PUFA food sources are diverse in human diets and few epidemiologic studies have examined whether associations between dietary PUFAs and breast cancer risk vary according to food sources or antioxidant intakes. The relationship between individual PUFA intakes estimated from diet history questionnaires and breast cancer risk was examined among 56,007 French women. During 8 years of follow‐up, 1,650 women developed invasive breast cancer. Breast cancer risk was not related to any dietary PUFA overall; however, opposite associations were seen according to food sources, suggesting other potential effects than PUFA per se. Breast cancer risk was inversely associated with α‐linolenic acid (ALA) intake from fruit and vegetables [highest vs. lowest quintile, hazard ratio (HR) 0.74; 95% confidence interval (CI) 0.63, 0.88; p trend < 0.0001], and from vegetable oils (HR 0.83; 95% CI 0.71, 0.97; p trend 0.017). Conversely, breast cancer risk was positively related to ALA intake from nut mixes (p trend 0.004) and processed foods (p trend 0.068), as was total ALA intake among women in the highest quintile of dietary vitamin E (p trend 0.036). A significant interaction was also found between ω‐6 and long‐chain ω‐3 PUFAs, with breast cancer risk inversely related to long‐chain ω‐3 PUFAs in women belonging to the highest quintile of ω‐6 PUFAs (p interaction 0.042). These results emphasize the need to consider food sources, as well as interactions between fatty acids and with antioxidants, when evaluating associations between PUFA intakes and breast cancer risk. © 2008 Wiley‐Liss, Inc.     

Low‐risk factor profile,estrogen levels,and breast cancer risk among postmenopausal women

Obesity, alcohol consumption, physical inactivity and postmenopausal hormone use are known modifiable risk factors for breast cancer. We aim to measure incidence rates of breast cancer for women with favorable levels on all 4 risk factors (BMI ≤ 30 kg/m², alcohol <1 drink/week, physically active and no current hormone use) and to evaluate their associations with estrogen. The 5,054 postmenopausal women in the Copenhagen City Heart Study were asked about risk factors at baseline in 1981–3 and were followed until 2002 in the Danish Cancer Registry, with <0.1% loss to follow‐up. Estradiol was measured in a subset of 1,042 women. During follow‐up, 263 women developed breast cancer. Twenty‐six percent of the women had a favourable risk factor profile, and their breast cancer rates were markedly lower (154 per 100,000 years) than women with 3+ risk factors (460 per 100,000 years). One, two and three risk factors were associated with hazard ratios of 1.38 (95% CI: 0.99; 1.92), 1.84 (1.26; 2.67) and 2.79 (1.59; 4.88) compared to women with a favourable profile. Each of the risk factors was associated with estrogen. In conclusion, the risk of breast cancer was markedly lower for women with a favourable risk profile than for other women and lower estrogen levels is a possible explanation. © 2008 Wiley‐Liss, Inc.     

Passive smoking and breast cancer risk among non-smoking Chinese women

Our purpose was to evaluate whether passive exposure to cigarette smoke may be related to breast cancer risk. Data from the Shanghai Breast Cancer Study, a large population-based study of 1459 breast cancer cases and 1556 controls aged 25-64 years, were analyzed. Respective response rates were 91.1% and 90.3%. Passive smoking questions were added to all face-to-face interviews 7 months into the study. Women were asked about exposure to their husbands' smoke at home as well as exposure in the workplace. Analyses were restricted to the 1013 cases and 1117 controls with passive tobacco smoke exposure data who had never actively smoked. Over 60% of controls reported some exposure to a husband's smoke and over 40% reported exposure to passive smoke in the workplace. Overall, there was no apparent association between any passive smoke exposure or exposure to a husband's smoke and breast cancer risk. There was some evidence of an elevated breast cancer risk associated with passive smoking exposure of 5 hr or more per day in the workplace (OR = 1.6, 95% confidence interval 1.0-2.4; p for trend = 0.02). This association warrants further investigation.     

Low-to-moderate alcohol intake and breast cancer risk in Chinese women

Background:

Despite extensive investigation of the association between alcohol consumption and breast cancer risk, effect of low-to-moderate alcohol intake on breast cancer incidence has been inconsistent.

Methods:

A case–control study was conducted in China, 2004–2005 to examine the association by menopausal status, oestrogen (ER) and progesterone receptor (PR) status of the tumour. There were 1009 incident cases with histologically confirmed breast cancer and 1009 age-matched controls recruited. We assessed alcohol consumption by face-to-face interview using a validated questionnaire and obtained tumour ER and PR status from pathology reports.

Results:

Low-to-moderate alcohol consumption was inversely associated with breast cancer risk. Compared with nondrinkers, the adjusted odds ratios (ORs) for alcohol <5 g per day were 0.41 (95% confidence interval 0.27–0.62) and 0.62 (0.48–0.79) in postmenopausal and premenopausal women, respectively. The inverse association was consistent for alcohol <15 g per day across hormone receptor status groups with ORs of 0.36–0.56 in postmenopausal women and 0.57–0.64 in premenopausal women. An exception was that alcohol ⩾15 g per day appeared to increase the risk of breast cancers with discordant receptor status in postmenopausal women, that is, ER+/PR− or ER−/PR+ (4.27, 1.57–11.65).

Conclusion:

We found that low-to-moderate alcohol intake was not associated with increased risk of breast cancer in pre- or postmenopausal Chinese women. Future studies are required to understand differences in effect of alcohol on breast cancers by tumour hormone receptor status.     

Flame-broiled food, NAT2acetylator phenotype, and breast cancer risk among women with benign breast disease

Purpose The objective of this study was to examine the association between flame-broiled food consumption, a source of heterocyclic amine exposure, and the development of breast cancer among cohort of women with benign breast disease (BBD). The variation of the association by acetylation phenotype, as determined by the genotypes of selected N-acetyltransferase 2 (NAT2) enzymes, was also examined.Methods Among participants in an ongoing cohort study, 1187 women reported having a breast biopsy for BBD and completed a food frequency questionnaire. NAT2 G857A, NAT2 T341C, and NAT2 G590A genotypes were determined using DNA extracted from blood specimens collected in 1989. Incident cases of breast cancer were identified through linkage of the cohort participants with the Washington County Cancer Registry and the Maryland State Cancer Registry. Follow-up for the BBD cohort began at study entry in 1989 and ended on April 28, 2003.Results Of the women in this study, 77 subsequently developed breast cancer. Results showed that, among rapid acetylators, flame-broiled food intake was associated with a statistically significant increase in the risk of breast cancer (odds ratio (OR) 2.62; 95% confidence interval (CI) 1.06, 6.46). No association was observed between flame-broiled food intake and breast cancer among slow acetylators (OR 0.75; 95% CI 0.39, 1.43).Conclusions These findings suggest that flame-broiled food may be a modifiable risk factor for the progression of BBD to invasive breast cancer among women who have genotypes consistent with rapid acetylation.     

Intake of whole grain products and risk of breast cancer by hormone receptor status and histology among postmenopausal women

No clear relationship between whole grain products and risk of breast cancer has been established. In a large prospective cohort study, we investigated the association between intake of whole grain products and risk of breast cancer by tumour receptor status [oestrogen receptor (ER) and progesterone receptor (PR)] and tumour histology (ductal/lobular). It was further investigated whether the association differed by use of hormone replacement therapy (HRT). The study included 25,278 postmenopausal women participating in the Danish Diet, Cancer and Health cohort study (1993–1997). During a mean follow‐up time of 9.6 years, 978 breast cancer cases were diagnosed. Associations between intake of whole grain products and the breast cancer rate were analysed using Cox's regression model. A higher intake of whole grain products was not associated with a lower risk of breast cancer. Per an increment in intake of total whole grain products of 50 g per day the adjusted incidence rate ratio (95% confidence interval) was 1.01 (0.96–1.07). Intake of rye bread, oatmeal and whole grain bread was not associated with breast cancer risk. No association was observed between the intake of total or specific whole grain products and the risk of developing ER+, ER?, PR+, PR?, combined ER/PR status, ductal or lobular breast cancer. Furthermore, there was no interaction between intake of whole grain products and use of HRT on risk of breast cancer. In conclusion, intake of whole grain products was not associated with risk of breast cancer in a cohort of Danish postmenopausal women. © 2008 Wiley‐Liss, Inc.     

Risk of breast cancer among Norwegian women with visual impairment

Experimental studies suggest that melatonin has a protective effect against breast cancer. Exposure to light suppresses melatonin secretion, but to a lesser degree in totally blind persons. Breast cancer was investigated in a cohort of 15 412 Norwegian visually impaired women. The risk among totally blind women was 0.64 (95% CI = 0.21-1.49, 5 cases only), and for those who became blind before age of 65, the SIR was 0.51 (95% CI = 0.11-1.49). Our findings give support to the 'melatonin hypothesis'.     

Social adjustment among Chinese women following breast cancer surgery

Background: How breast cancer surgery affects social adjustment among Chinese women is unknown, as are factors predicting such adjustment. Methods: 405 Chinese women receiving surgery for localized breast cancer completed Social Adjustment Scales (Ch‐SAS) at 1‐, 4‐ and 8‐months post‐operatively. Subscale scores were regressed on baseline (days 3–12 post‐operatively) measures of treatment decision‐making difficulty (TDMD), self‐efficacy (GSeS), consultation satisfaction (C‐MISS‐R), psychological (CHQ‐12) and physical distress (PD), and 1‐month follow‐up optimism (C‐LOT‐R), and disappointment (E‐OI), fully adjusted for demographic and clinical factors. Results: All Ch‐SAS subscales except appearance & sexuality changed significantly over 8‐months follow‐up: Enjoyment of social activities (F=27.38, df 2, p<0.001) and self‐image (F=3.63, df 2, p=0.027) improved slightly. Family interaction (F=26.63, df 2, p<0.001) and interaction with friends (F=3.37, df 2, p=0.035) declined slightly. Family and friends interaction subscales were predominantly predicted by high self‐efficacy and optimism, whereas self‐image and appearance & sexuality subscales were predominantly predicted by low treatment outcome disappointment, TDM difficulties, baseline psychological morbidity and high self‐efficacy. Enjoyment of social activities was predicted by low baseline psychological distress and concurrent physical symptom distress. Conclusion: High self‐efficacy and optimism predicted women who have better social relationships with friends and family. Higher self‐efficacy, low TDM difficulties, less disappointment with treatment outcome and low psychological and physical distress predicted better adjustment to self‐image and body image. Copyright © 2009 John Wiley & Sons, Ltd.     

Impact of newly diagnosed breast cancer on quality of life among Chinese women

Background Being diagnosed with breast cancer is a very stressful event that has a profound impact on multiple aspects of a patient’s daily life. Little is known about the quality of life (QOL) of Chinese women with newly diagnosed breast cancer. Methods The authors evaluated QOL in 2,236 Chinese women with newly diagnosed breast cancer who were recruited into the Shanghai Breast Cancer Survival Study between April 1, 2002 and March 31, 2004. Patients’ QOL was assessed after cancer diagnosis (median time 6.4 months; range 3.6–11.1 months) by using the General Quality of Life Inventory. Multiple linear regression models were used to analyze the associations of QOL outcomes with medical and socio-demographic factors. Results Patients showed significantly worse overall QOL and perceived health status than healthy women, reflected mainly by lower QOL scores in physical and psychological well-being domains. Completion of radiotherapy, ever use of tamoxifen, being underweight, having an increased number of chronic diseases, and low household income were significantly associated with lower overall QOL scores after adjusting for other factors. Age at diagnosis was inversely associated with physical well-being, positively associated with material well-being, and had minimal influence on overall QOL. Stage of disease, chemotherapy, and education were only associated with certain domains, but had no influence on overall QOL. Estrogen receptor/progesterone receptor status and type of surgery or immunotherapy did not appear to be associated with QOL. Conclusions The findings of the present study provide important information on QOL and their correlates among Chinese women with newly diagnosed breast cancer and are helpful in developing treatment strategies accordingly.     

Trajectories of psychological distress among Chinese women diagnosed with breast cancer

Background: The distinct trajectories of psychological distress over the first year of the diagnosis with breast cancer (BC) and its determinants have not been explored. Methods: 285 of 405 Chinese women receiving surgery for BC were assessed at 5‐day, 1‐month, 4‐month, and 8‐month post‐surgery on measures of psychological distress, optimism, treatment decision‐making (TDM) difficulties, satisfaction with treatment outcome, satisfaction with medical consultation, and physical symptom distress. Latent growth mixture modelling identified trajectories of psychological response to BC. Multinominal logistic regression compared TDM difficulties, satisfaction with treatment outcome, satisfaction with medical consultation, optimism, and physical symptom distress, by distress pattern adjusted for age, education, employment status, and stage of disease. Results: Four distinct trajectories of distress were identified, namely, resilience (66%), chronic distress (15%), recovered (12%), and delayed‐recovery (7%). TDM difficulties, optimism, satisfaction with consultation, and physical symptom distress predicted distress trajectories. Psychologically resilient women had less physical symptom distress at early post‐surgery compared with women with other distress patterns. Compared with the resilient group, women in the recovered or chronic distress groups experienced greater TDM difficulties, whereas women in the delayed‐recovery group reported greater dissatisfaction with the initial medical consultation. Women in the chronic distress group reported greater pessimistic outlook. Conclusion: Optimism and better early post‐operative treatment outcomes predicted resilience to distress. Pre‐operative interventions helping women to establish a realistic expectation of treatment outcome may minimize disappointment with treatment outcome and resultant distress, whereas post‐operative rehabilitation should focus on symptom management. Copyright © 2009 John Wiley & Sons, Ltd.     

Healthy lifestyle and risk of breast cancer among postmenopausal women in the European Prospective Investigation into Cancer and Nutrition cohort study

Breast cancer is the most common cancer among women and prevention strategies are needed to reduce incidence worldwide. A healthy lifestyle index score (HLIS) was generated to investigate the joint effect of modifiable lifestyle factors on postmenopausal breast cancer risk. The study included 242,918 postmenopausal women from the multinational European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, with detailed information on diet and lifestyle assessed at baseline. The HLIS was constructed from five factors (diet, physical activity, smoking, alcohol consumption and anthropometry) by assigning scores of 0–4 to categories of each component, for which higher values indicate healthier behaviours. Hazard ratios (HR) were estimated by Cox proportional regression models. During 10.9 years of median follow‐up, 7,756 incident breast cancer cases were identified. There was a 3% lower risk of breast cancer per point increase of the HLIS. Breast cancer risk was inversely associated with a high HLIS when fourth versus second (reference) categories were compared [adjusted HR = 0.74; 95% confidence interval (CI): 0.66–0.83]. The fourth versus the second category of the HLIS was associated with a lower risk for hormone receptor double positive (adjusted HR = 0.81, 95% CI: 0.67–0.98) and hormone receptor double negative breast cancer (adjusted HR = 0.60, 95% CI: 0.40–0.90). Findings suggest having a high score on an index of combined healthy behaviours reduces the risk of developing breast cancer among postmenopausal women. Programmes which engage women in long term health behaviours should be supported.