Light-at-night, circadian disruption and breast cancer: assessment of existing evidence
01 Aug 2009-International Journal of Epidemiology (Oxford University Press)-Vol. 38, Iss: 4, pp 963-970
TL;DR: If a consensus eventually emerges that LAN does increase risk, then the mechanisms for the effect are important to elucidate for intervention and mitigation and will provide for the development of lighting technologies at home and at work that minimize circadian disruption, while maintaining visual efficiency and aesthetics.
Abstract: Background Breast cancer incidence is increasing globally for largely unknown reasons. The possibility that a portion of the breast cancer burden might be explained by the introduction and increasing use of electricity to light the night was suggested >20 years ago.
Methods The theory is based on nocturnal light-induced disruption of circadian rhythms, notably reduction of melatonin synthesis. It has formed the basis for a series of predictions including that non-day shift work would increase risk, blind women would be at lower risk, long sleep duration would lower risk and community nighttime light level would co-distribute with breast cancer incidence on the population level.
Results Accumulation of epidemiological evidence has accelerated in recent years, reflected in an International Agency for Research on Cancer (IARC) classification of shift work as a probable human carcinogen (2A). There is also a strong rodent model in support of the light-at-night (LAN) idea.
Conclusion If a consensus eventually emerges that LAN does increase risk, then the mechanisms for the effect are important to elucidate for intervention and mitigation. The basic understanding of phototransduction for the circadian system, and of the molecular genetics of circadian rhythm generation are both advancing rapidly, and will provide for the development of lighting technologies at home and at work that minimize circadian disruption, while maintaining visual efficiency and aesthetics. In the interim, there are strategies now available to reduce the potential for circadian disruption, which include extending the daily dark period, appreciate nocturnal awakening in the dark, using dim red light for nighttime necessities, and unless recommended by a physician, not taking melatonin tablets.
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01 Jan 2016
TL;DR: Electrical light, which has been a widespread benefit only during about the past 100 years, is new in an evolutionary perspective, and has among priceless advantages given humans the ability to work during the normal dark part of the day (evening, night and early morning).
Cites background from "Light-at-night, circadian disruptio..."
...Later, this hypothesis was further applied to aspects of desynchronisation of the master circadian pacemaker (suprachiasmatic nucleus) with peripheral oscillators due to slow adaption and synchronisation to rapid transitions between different shift schedules, different expressions in circadian genes, and sleep deprivation followed by night shift work in initiating or promoting breast cancer and probably other cancers.(2) The first epidemiological studies testing Steven’s hypothesis were published in 2001, and all three independent studies from Denmark and the USA showed significantly increased breast cancer risks, including a dose-related increase in risk with increasing years of non-daytime work....
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01 Jun 2018
TL;DR: Mais estudos sobre o assunto são necessários de forma a se compreender melhor a possível relação entre o ciclo circadiano e a susceptibilidade ao desenvolvimento de neoplasias, especialmente o câncer de mama.
Abstract: 1School of Medical, Pharmaceutical and Biomedical Sciences, Pontifícia Universidade Católica de Goiás (PUC-Goiás) – Goiânia (GO), Brazil. 2Centro Brasileiro de Radioterapia, Oncologia e Mastologia – Goiânia (GO), Brazil. 3Tumor Biology Laboratory, Hospital Araújo Jorge, Associação de Combate ao Câncer em Goiás – Goiânia (GO), Brazil. 4Nursing school, Universidade Federal de Goiás – Goiânia (GO), Brazil. 5Postgraduate Program in Environmental Sciences and Health, PUC-Goiás – Goiânia (GO), Brazil. *Corresponding author: marciocmed@gmail.com Conflict of interests: nothing to declare. Received on: 03/13/2018. Accepted on: 03/29/2018 Introdução: O ciclo circadiano desempenha vários papéis nas funções do organismo e é importante para a manutenção da saúde, quando sincronizado. Atualmente, um dos principais fatores de risco para a mudança do ciclo vigília-sono na população é a alta exposição à luz noturna, desregulando consequentemente o ciclo circadiano, inibindo a liberação de melatonina e favorecendo a oncogênese. Objetivo: O objetivo deste estudo foi identificar as possíveis associações entre dessincronização do ritmo circadiano e o câncer de mama. Métodos: Trata-se de um estudo descritivo de corte transversal em que foram utilizados dois instrumentos de coleta: um questionário sociodemográfico e o questionário matutino-vespertino de Horne e Ostberg. Os questionários foram aplicados a um grupo de 74 mulheres em um serviço de oncologia. Resultados: Para avaliar se os fatores discriminantes como o trabalho noturno e o cronotipo exerceram alguma influência sobre o fator discriminado, câncer de mama, foi aplicado o teste do χ2, que revelou semelhança entre as características dos grupos estudados. Conclusões: Mais estudos sobre o assunto são necessários de forma a se compreender melhor a possível relação entre o ciclo circadiano e a susceptibilidade ao desenvolvimento de neoplasias, especialmente o câncer de mama.
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01 Oct 2010
TL;DR: In this article, the role of individual genes in the interrelationships between processes of natural and accelerated, by environmental factors, aging was analyzed for genetically modified mice with phenotypic signs of accelerated aging.
Abstract: In ours and other studies, data have been obtained testifying to the fact that, under the action of various classes of chemical carcinogenic agents (polycyclic aromatic hydrocarbons, nitrous compouds, aromatic amines), other mutagens, ionizing radiation, extremely low frequency (50 Hz), electromagnetic fields (EMFs), constant illumination, and smoking, in the basic homeostatic systems of an organism (nervous, endocrine, immune, and energy homeostasis) premature hormonal, and metabolic shifts occur similar to those arising during physiological aging. These shifts create favorable conditions for the promotion and progression stages of carcinogenesis. The use of genetically modified animals (mutant, transgenic, or knockout) opens new possibilities for analyzing the role of individual genes in the interrelationships between processes of natural and accelerated, by environmental factors, aging. For genetically modified mice with phenotypic signs of accelerated aging, as a rule, the frequency of new-growth development increases, then for animals with decelerated aging, an increase in the latent period of tumor development and/or a decrease in the frequency of their appearance is noted. The application of geroprotectors under conditions of increased risk of accelerated aging resulting genetically or from adverse environmental factors (carcinogens, mutagens, peculiarities in diet) can be a first line prevention against cancer.
References
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TL;DR: The criteria outlined in "The Environment and Disease: Association or Causation?" help identify the causes of many diseases, including cancers of the reproductive system.
Abstract: In 1965, Austin Bradford Hill published the article "The Environment and Disease: Association or Causation?" in the Proceedings of the Royal Society of Medicine. In the article, Hill describes nine criteria to determine if an environmental factor, especially a condition or hazard in a work environment, causes an illness. The article arose from an inaugural presidential address Hill gave at the 1965 meeting of the Section of Occupational Medicine of the Royal Society of Medicine in London, England. The criteria he established in the article became known as the Bradford Hill criteria and the medical community refers to them when determining whether an environmental condition causes an illness. The criteria outlined in "The Environment and Disease: Association or Causation?" help identify the causes of many diseases, including cancers of the reproductive system.
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Journal Article•
TL;DR: This paper contrasts Bradford Hill’s approach with a currently fashionable framework for reasoning about statistical associations – the Common Task Framework – and suggests why following Bradford Hill, 50+ years on, is still extraordinarily reasonable.
Abstract: In 1965, Sir Austin Bradford Hill offered his thoughts on: “What aspects of [an] association should we especially consider before deciding that the most likely interpretation of it is causation?” He proposed nine means for reasoning about the association, which he named as: strength, consistency, specificity, temporality, biological gradient, plausibility, coherence, experiment, and analogy. In this paper, we look at what motivated Bradford Hill to propose we focus on these nine features. We contrast Bradford Hill’s approach with a currently fashionable framework for reasoning about statistical associations – the Common Task Framework. And then suggest why following Bradford Hill, 50+ years on, is still extraordinarily reasonable.
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Abstract: Bright artificial light suppressed nocturnal secretion of melatonin in six normal human subjects. Room light of less intensity, which is sufficient to suppress melatonin secretion in other mammals, failed to do so in humans. In contrast to the results of previous experiments in which ordinary room light was used, these findings establish that the human response to light is qualitatively similar to that of other mammals.
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TL;DR: The results suggest that, in humans, a single photopigment may be primarily responsible for melatonin suppression, and its peak absorbance appears to be distinct from that of rod and cone cellphotopigments for vision.
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1,708 citations