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Open AccessJournal ArticleDOI

Night-shift work and breast cancer--a systematic review and meta-analysis.

TLDR
There is insufficient evidence for a link between night-shift work and breast cancer, based on the low quality of exposure data and the difference in effect by study design.
Abstract
Objective The aim of this review was to synthesize the evidence on the potential relationship between nightshift work and breast cancer. Methods We searched multiple databases for studies comparing women in shift work to those with no-shift work reporting incidence of breast cancer. We calculated incremental risk ratios (RR) per five years of night-shift work and per 300 night shift increases in exposure and combined these in a random effects dose–response meta-analysis. We assessed study quality in ten domains of bias. Results We identified 16 studies: 12 case–control and 4 cohort studies. There was a 9% risk increase per five years of night-shift work exposure in case–control studies [RR 1.09, 95% confidence interval (95% CI) 1.02–1.20; I 2 =37%, 9 studies], but not in cohort studies (RR 1.01, 95% CI 0.97–1.05; I 2 =53%, 3 studies). Heterogeneity was significant overall (I 2 =55%, 12 studies). Results for 300 night shifts were similar (RR 1.04, 95% CI 1.00–1.10; I 2 =58%, 8 studies). Sensitivity analysis using exposure transformations such as cubic splines, a fixed-effect model, or including only better quality studies did not change the results. None of the 16 studies had a low risk of bias, and 6 studies had a moderate risk. Conclusions Based on the low quality of exposure data and the difference in effect by study design, our findings indicate insufficient evidence for a link between night-shift work and breast cancer. Objective prospective exposure measurement is needed in future studies.

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Health consequences of shift work and insufficient sleep

TL;DR: Evidence shows that the effect of shift work on sleep mainly concerns acute sleep loss in connection with night shifts and early morning shifts, and Laboratory studies indicate that cardiometabolic stress and cognitive impairments are increased by shift work, as well as by sleep loss.
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Association between light at night, melatonin secretion, sleep deprivation, and the internal clock: Health impacts and mechanisms of circadian disruption.

TL;DR: Countermeasures to the effects of ALAN, such as melatonin, bright light, or psychotropic drugs, have been proposed as a means to combat circadian clock disruption and improve adaptation to shift and night work.
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Circadian misalignment and health

TL;DR: The role of circadian misalignment as a risk factor for disease in the general population and in clinical populations, including circadian rhythm sleep disorders and psychiatric disorders is described.
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Night shift work at specific age ranges and chronic disease risk factors

TL;DR: The results indicate that nightshift work may contribute to an adverse chronic disease risk profile, and that risk factors may vary depending on the age at which night shift work was performed.
References
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Journal ArticleDOI

Bias in meta-analysis detected by a simple, graphical test

TL;DR: Funnel plots, plots of the trials' effect estimates against sample size, are skewed and asymmetrical in the presence of publication bias and other biases Funnel plot asymmetry, measured by regression analysis, predicts discordance of results when meta-analyses are compared with single large trials.
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Global Patterns of Cancer Incidence and Mortality Rates and Trends

TL;DR: Changing global incidence and mortality patterns for select common cancers and the opportunities for cancer prevention in developing countries are described.
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Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study.

TL;DR: Increasing body mass index is associated with a significant increase in the risk of cancer for 10 out of 17 specific types examined, and for colorectal cancer, malignant melanoma, breast cancer, and endometrial cancer, the effect ofBody mass index on risk differed significantly according to menopausal status.
Journal ArticleDOI

Generalized least squares for trend estimation of summarized dose–response data

TL;DR: In this article, a command, glst, is presented for trend estimation across different exposure levels for either single or multiple summarized case-control, incidence-rate, and cumulative incidence data.
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