Breast cancer is increasingly prevalent in industrialized regions of the world, and exposure to light at night (LAN) has been proposed as a potential risk factor. Epidemiological observations have documented an increased breast cancer risk among female night-shift workers, and strong experimental evidence for this relationship has also been found in rodent models. Indirect support for the LAN hypothesis comes from studies involving blind women, sleep duration, bedroom light levels, and community nighttime light levels. This article reviews the literature, discusses possible mechanisms of action, and provides recommendations for occupational health nursing research, practice, and education. Research is needed to further explore the relationship between exposure to LAN and breast cancer risk and elucidate the mechanisms underlying this relationship before interventions can be designed for prevention and mitigation of breast cancer.
References
1.
AlpertM.CaromeE.KubulinsV.HanslerR. (2009). Nighttime use of special spectacles or light bulbs that block blue light may reduce the risk of cancer. Medical Hypotheses, 73(3), 324–325. doi:10.1016/j.mehy.2009.02.027
2.
BlaskD. E. (2009). Melatonin, sleep disturbance and cancer risk. Sleep Medicine Reviews, 13(4), 257–264. doi:10.1016/j.smrv.2008.07.007
3.
BlaskD. E.BrainardG. C.DauchyR. T.HanifinJ. P.DavidsonL. K.KrauseJ. A. (2005). Melatonin-depleted blood from premenopausal women exposed to light at night stimulates growth of human breast cancer xenografts in nude rats. Cancer Research, 65(23), 11174–11184. doi:10.1158/0008-5472.CAN-05-1945
4.
BlaskD. E.DauchyR. T.BrainardG. C.HanifinJ. P. (2009). Circadian stage-dependent inhibition of human breast cancer metabolism and growth by the nocturnal melatonin signal: Consequences of its disruption by light at night in rats and women. Integrative Cancer Therapies, 8(4), 347–353. doi:10.1177/1534735409352320
5.
BlaskD. E.DauchyR. T.SauerL. A.KrauseJ. A.BrainardG. C. (2003). Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: Impact of constant light-induced nocturnal melatonin suppression. Breast Cancer Research and Treatment, 79(3), 313–320.
6.
CosS.GonzálezA.Martínez-CampaC.MediavillaM. D.Alonso-GonzálezC.Sánchez-BarcelóE. J. (2006). Estrogen-signaling pathway: A link between breast cancer and melatonin on-costatic actions. Cancer Detection and Prevention, 30(2), 118–128. doi:10.1016/j.cdp.2006.03.002
7.
CostaG.HausE.StevensR. (2010). Shift work and cancer: Considerations on rationale, mechanisms, and epidemiology. Scandinavian Journal of Work, Environment, & Health, 36(2), 163–179.
8.
DauchyR. T.DauchyE. M.TirrellR. P.HillC. R.DavidsonL. K.GreeneM. W. (2010). Dark-phase light contamination disrupts circadian rhythms in plasma measures of physiology and metabolism. Comparative Medicine, 60(5), 348–356.
9.
DauchyR. T.SauerL. A.BlaskD. E.VaughanG. M. (1997). Light contamination during the dark phase in “photoperiodically controlled” animal rooms: Effect on tumor growth and metabolism in rats. Laboratory Animal Science, 47(5), 511–518.
10.
DavisS.MirickD. K.StevensR. G. (2001). Night shift work, light at night, and risk of breast cancer. Journal of the National Cancer Institute, 93(20), 1557–1562.
11.
DumontM.BlaisH.RoyJ.PaquetJ. (2009). Controlled patterns of daytime light exposure improve circadian adjustment in simulated night work. Journal of Biological Rhythms, 24(5), 427–437. doi:10.1177/0748730409343795
12.
FeigelsonH. S.HendersonB. E. (1996). Estrogens and breast cancer. Carcinogenesis, 17, 2279–2284.
13.
Flynn-EvansE. E.StevensR. G.TabandehH.SchernhammerE. S.LockleyS. W. (2009). Total visual blindness is protective against breast cancer. Cancer Causes & Control, 20(9), 1753–1756. doi:10.1007/s10552-009-9405-0
14.
FuL.LeeC. C. (2003). The circadian clock: Pacemaker and tumour suppressor. Nature Reviews: Cancer, 3(5), 350–361. doi:10.1038/nrc1072
15.
GarlandC. F.GarlandF. C.GorhamE. D.LipkinM.NewmarkH.MohrS. B. (2006). The role of Vitamin D in cancer prevention. American Journal of Public Health, 96(2), 252–261. doi:10.2105/AJPH.2004.045260
16.
GrantS. G.MelanM. A.LatimerJ. J.Witt-EnderbyP. A. (2009). Melatonin and breast cancer: Cellular mechanisms, clinical studies and future perspectives. Expert Reviews in Molecular Medicine, 11, e5. doi:10.1017/S1462399409000982
17.
GrundyA.SanchezM.RichardsonH.TranmerJ.BorugianM.GrahamC. H. (2009). Light intensity exposure, sleep duration, physical activity, and biomarkers of melatonin among rotating shift nurses. Chronobiology International, 26(7), 1443–1461. doi:10.3109/07420520903399987
18.
GrundyA.TranmerJ.RichardsonH.GrahamC. H.AronsonK. J. (2011). The influence of light at night exposure on melatonin levels among Canadian rotating shift nurses. Cancer Epidemiology, Biomarkers, & Prevention, 20(11), 2404–2412. doi:10.1158/1055-9965.EPI-11-0427
19.
HansenJ. (2001). Light at night, shiftwork, and breast cancer risk. Journal of the National Cancer Institute, 93(20), 1513–1515.
20.
HansenJ.StevensR. G. (2011). Case-control study of shift-work and breast cancer risk in Danish nurses: Impact of shift systems. European Journal of Cancer. doi:10.1016/j.ejca.2011.07.005
21.
HigginsP. A.WinkelmanC.LipsonA. R.GuoS. E.RodgersJ. (2007). Light measurement in the hospital: A comparison of two methods. Research in Nursing & Health, 30(1), 120–128. doi:10.1002/nur.20167
22.
HoffmanA. E.YiC. H.ZhengT.StevensR. G.LeadererD.ZhangY. (2010). CLOCK in breast tumorigenesis: Genetic, epigenetic, and transcriptional profiling analyses. Cancer Research, 70(4), 1459–1468.
23.
International Agency for Research on Cancer. (2007). IARC monographs on the evaluation of carcinogenic risks to humans: Painting, firefighting, and shiftwork. Lyon, France: Author.
24.
JardimA. C.PawleyM. D.CheesemanJ. F.GuesgenM. J.SteeleC. T.WarmanG. R. (2011). Validating the use of wrist-level light monitoring for in-hospital circadian studies. Chronobiology International, 28(9), 834–840. doi:10.3109/07420528.2011.611603
25.
KakizakiM.KuriyamaS.SoneT.Ohmori-MatsudaK.HozawaA.NakayaN. (2008). Sleep duration and the risk of breast cancer: The Ohsaki Cohort Study. British Journal of Cancer, 99(9), 1502–1505. doi:10.1038/sj.bjc.6604684
26.
KamangarF.DoresG.AndersonW. (2006). Patterns of cancer incidence, mortality, and prevalence across five continents: Defining priorities to reduce cancer disparities in different geographic regions of the world. Journal of Clinical Oncology, 24(14), 2137–2150. doi:10.1200/JCO.2005.05.2308
27.
KayumovL.LoweA.RahmanS. A.CasperR. F.ShapiroC. M. (2007). Prevention of melatonin suppression by nocturnal lighting: Relevance to cancer. European Journal of Cancer Prevention, 16(4), 357–362. doi:10.1097/01.cej.0000215622.59122. d4
28.
KloogI.HaimA.StevensR. G.BarchanaM.PortnovB. A. (2008). Light at night co-distributes with incident breast but not lung cancer in the female population of Israel. Chronobiology International, 25(1), 65–81. doi:10.1080/07420520801921572
29.
KloogI.PortnovB. A.RennertH. S.HaimA. (2011). Does the modern urbanized sleeping habitat pose a breast cancer risk?Chronobiology International, 28(1), 76–80. doi:10.3109/07420528.2010.531490
30.
KloogI.StevensR. G.HaimA.PortnovB. A. (2010). Nighttime light level co-distributes with breast cancer incidence worldwide. Cancer Causes & Control, 21(12), 2059–2068. doi:10.1007/s10552-010-9624-4
31.
KnutsonK. L.SpiegelK.PenevP.Van CauterE. (2007). The metabolic consequences of sleep deprivation. Sleep Medicine Reviews, 11(3), 163–178. doi:10.1016/j.smrv.2007.01.002
32.
KuoS. J.ChenS. T.YehK. T.HouM. F.ChangY. S.HsuN. C. (2009). Disturbance of circadian gene expression in breast cancer. Virchows Archiv, 454(4), 467–474. doi:10.1007/s00428-009-0761-7
33.
LappeJ. M.Travers-GustafsonD.DaviesK. M.ReckerR. R.HeaneyR. P. (2007). Vitamin D and calcium supplementation reduces cancer risk: Results of a randomized trial. American Journal of Clinical Nutrition, 85(6), 1586–1591.
34.
LiQ.ZhengT.HolfordT. R.BoyleP.ZhangY.DaiM. (2010). Light at night and breast cancer risk: Results from a population-based case-control study in Connecticut, USA. Cancer Causes & Control, 21(12), 2281–2285. doi:10.1007/s10552-010-9653-z
35.
LieJ. A.RoessinkJ.KjaerheimK. (2006). Breast cancer and night work among Norwegian nurses. Cancer Causes & Control, 17(1), 39–44.
36.
LieJ. S.KjuusH.ZienolddinyS.HaugenA.StevensR. G.KjærheimK. (2011). Night work and breast cancer risk among Norwegian nurses: Assessment by different exposure metrics. American Journal of Epidemiology, 173(11), 1272–1279. doi:10.1093/aje/kwr014
37.
MadiganM. P.ZieglerR. G.BenichouJ.ByrneC.HooverR. N. (1995). Proportion of breast cancer cases in the United States explained by well-established risk factors. Journal of the National Cancer Institute, 87(22), 1681–1685.
38.
NagataC.KawakamiN.ShimizuH. (1997). Trends in the incidence rate and risk factors for breast cancer in Japan. Breast Cancer Research and Treatment, 44(1), 75–82.
39.
NagataC.NagaoY.YamamotoS.ShibuyaC.KashikiY.ShimizuH. (2008). Light exposure at night, urinary 6-sulfatox-ymelatonin, and serum estrogens and androgens in postmenopausal Japanese women. Cancer Epidemiology, Biomarkers, & Prevention, 17(6), 1418–1423. doi:10.1158/1055-9965.EPI-07-0656
40.
O'LearyE. S.SchoenfeldE. R.StevensR. G.KabatG. C.HendersonK.GrimsonR. (2006). Shift work, light at night, and breast cancer on Long Island, New York. American Journal of Epidemiology, 164(4), 358–366. doi:10.1093/aje/kwj211
41.
ParkinD. M. (2004). International variation. Oncogene, 23(38), 6329–6340. doi:10.1038/sj.onc.1207726
42.
PeschB.HarthV.RabsteinS.BaischC.SchiffermannM.PallapiesD. (2010). Night work and breast cancer: Results from the German GENICA study. Scandinavian Journal of Work, Environment, & Health, 36(2), 134–141.
43.
PinheiroS. P.SchernhammerE. S.TworogerS. S.MichelsK. B. (2006). A prospective study on habitual duration of sleep and incidence of breast cancer in a large cohort of women. Cancer Research, 66(10), 5521–5525. doi:10.1158/0008-5472.CAN-05-4652
44.
PronkA.JiB.ShuX.XueS.YangG.LiH. (2010). Night-shift work and breast cancer risk in a cohort of Chinese women. American Journal of Epidemiology, 171(9), 953–959. doi:10.1093/aje/kwq029
45.
PukkalaE.OjamoM.RudankoS. L.StevensR. G.VerkasaloP. K. (2006). Does incidence of breast cancer and prostate cancer decrease with increasing degree of visual impairment. Cancer Causes & Control, 17(4), 573–576. doi:10.1007/s10552-005-9005-6
46.
PuttonenS.HärmäM.HublinC. (2010). Shift work and cardiovascular disease: Pathways from circadian stress to morbidity. Scandinavian Journal of Work, Environment, & Health, 36(2), 96–108.
47.
ReaM. S.BronsJ. A.FigueiroM. G. (2011). Measurements of light at night (LAN) for a sample of female school teachers. Chronobiology International, 28(8), 673–680. doi:10.3109/07420528.20 11.602198
48.
RheeH. V.CoeberghJ. W.VriesE. D. (2009). Sunlight, vitamin D and the prevention of cancer: A systematic review of epidemiological studies. European Journal of Cancer Prevention, 18, 458–475. doi:10.1097/CEJ.0b013e32832f9bb1
49.
SchernhammerE. S.KroenkeC. H.LadenF.HankinsonS. E. (2006). Night work and risk of breast cancer. Epidemiology, 17(1), 108–111.
50.
SchernhammerE. S.LadenF.SpeizerF. E.WillettW. C.HunterD. J.KawachiI. (2001). Rotating night shifts and risk of breast cancer in women participating in the Nurses' Health Study. Journal of the National Cancer Institute, 93(20), 1563–1568.
51.
StevensR. G. (2006). Artificial lighting in the industrialized world: Circadian disruption and breast cancer. Cancer Causes & Control, 17(4), 501–507. doi:10.1007/s10552-005-9001-x
52.
StevensR. G. (2009). Light-at-night, circadian disruption and breast cancer: Assessment of existing evidence. International Journal of Epidemiology, 38(4), 963–970. doi:10.1093/ije/dyp178
53.
StevensR. G.HansenJ.CostaG.HausE.KauppinenT.AronsonK. J. (2011). Considerations of circadian impact for defining “shift work” in cancer studies: IARC working group report. Occupational & Environmental Medicine, 68(2), 154–162. doi:10.1136/oem.2009.053512
54.
TamarkinL.CohenM.RoselleD.ReichertC.LippmanM.ChabnerB. (1981). Melatonin inhibition and pinealectomy enhancement of 7,12-dimethylbenz(a)anthracene-induced mammary tumours in the rat. Cancer Research, 41(11), 4432–4436.
55.
TravisR. C.AllenD. S.FentimanI. S.KeyT. J. (2004). Melatonin and breast cancer: A prospective study. Journal of the National Cancer Institute, 96(6), 475–482.
56.
VerkasaloP. K.LillbergK.StevensR. G.HublinC.PartinenM.KoskenvuoM. (2005). Sleep duration and breast cancer: A prospective cohort study. Cancer Research, 65(20), 9595–9600. doi:10.1158/0008-5472.CAN-05-2138
WuA. H.WangR.KohW.StanczykF. Z.LeeH.YuM. C. (2008). Sleep duration, melatonin and breast cancer among Chinese women in Singapore. Carcinogenesis, 29(6), 1244–1248. doi:10.1093/carcin/bgn100
59.
WuJ.DauchyR. T.TirrellP. C.WuS. S.LynchD. T.JitawatanaratP. (2011). Light at night activates IGF-1R/PDK1 signaling and accelerates tumor growth in human breast cancer xenografts. Cancer Research, 71(7), 2622–2631. doi:10.1158/0008-5472.CAN-10-3837
60.
YangX.WoodP. A.OhE. Y.Du-QuitonJ.AnsellC. M.HrusheskyW. J. (2009). Down regulation of circadian clock gene Period 2 accelerates breast cancer growth by altering its daily growth rhythm. Breast Cancer Research and Treatment, 117(2), 423–431. doi:10.1007/s10549-008-0133-z
61.
ZhuY.StevensR. G.LeadererD.HoffmanA.HolfordT.ZhangY. (2008). Nonsynonymous polymorphisms in the circadian gene NPAS2 and breast cancer risk. Breast Cancer Research and Treatment, 107(3), 421–425. doi:10.1007/s10549-007-9565-0
