Cancer Causes & Control

, Volume 26, Issue 1, pp 143–150 | Cite as

Shift work and breast cancer among women textile workers in Shanghai, China

  • Wenjin Li
  • Roberta M. Ray
  • David B. Thomas
  • Scott Davis
  • Michael Yost
  • Norman Breslow
  • Dao Li Gao
  • E. Dawn Fitzgibbons
  • Janice E. Camp
  • Eva Wong
  • Karen J. Wernli
  • Harvey Checkoway
Original paper



Although night-shift work has been associated with elevated risk of breast cancer in numerous epidemiologic studies, evidence is not consistent. We conducted a nested case–cohort study to investigate a possible association between shift work including a night shift and risk of breast cancer within a large cohort of women textile workers in Shanghai, China.


The study included 1,709 incident breast cancer cases and 4,780 non-cases. Data on historical shift work schedules were collected by categorized jobs from the factories, where the study subjects had worked, and then were linked to the complete work histories of each subject. No jobs in the factories involved exclusively night-shift work. Therefore, night shift was evaluated as part of a rotating shift work pattern. Hazard ratios and 95 % confidence intervals were calculated using Cox proportional hazards modeling adapted for the case–cohort design for years of night-shift work and the total number of nights worked. Additionally, analyses were repeated with exposures lagged by 10 and 20 years.


We observed no associations with either years of night-shift work or number of nights worked during the entire employment period, irrespective of lag intervals. Findings from the age-stratified analyses were very similar to those observed for the entire study population.


The findings from this study provide no evidence to support the hypothesis that shift work increases breast cancer risk. The positive association between shift work and breast cancer observed in Western populations, but not observed in this and other studies of the Chinese population, suggests that the effect of shift work on breast cancer risk may be different in Asian and Caucasian women.


Breast cancer Night-shift work Shift work Dose–response 


  1. 1.
    Althuis MD, Dozier JM, Anderson WF, Devesa SS, Brinton LA (2005) Global trends in breast cancer incidence and mortality 1973–1997. Int J Epidemiol 34:405–412PubMedCrossRefGoogle Scholar
  2. 2.
    Straif K, Baan R, Grosse Y et al (2007) Carcinogenicity of shift-work, painting, and fire-fighting. Lancet Oncol 8:1065–1066PubMedCrossRefGoogle Scholar
  3. 3.
    Schernhammer ES, Kroenke CH, Laden F, Hankinson SE (2006) Night work and risk of breast cancer. Epidemiology 17:108–111PubMedCrossRefGoogle Scholar
  4. 4.
    Schernhammer ES, Laden F, Speizer FE et al (2001) Rotating night shifts and risk of breast cancer in women participating in the nurses’ health study. J Natl Cancer Inst 93:1563–1568PubMedCrossRefGoogle Scholar
  5. 5.
    Lie JA, Roessink J, Kjaerheim K (2006) Breast cancer and night work among Norwegian nurses. Cancer Causes Control 17:39–44PubMedCrossRefGoogle Scholar
  6. 6.
    Pesch B, Harth V, Rabstein S et al (2010) Night work and breast cancer—results from the German GENICA study. Scand J Work Environ Health 36:134–141PubMedCrossRefGoogle Scholar
  7. 7.
    Pronk A, Ji BT, Shu XO et al (2010) Night-shift work and breast cancer risk in a cohort of Chinese women. Am J Epidemiol 171:953–959PubMedCentralPubMedCrossRefGoogle Scholar
  8. 8.
    Lie JA, Kjuus H, Zienolddiny S, Haugen A, Stevens RG, Kjaerheim K (2011) Night work and breast cancer risk among Norwegian nurses: assessment by different exposure metrics. Am J Epidemiol 173:1272–1279PubMedCrossRefGoogle Scholar
  9. 9.
    Kamdar BB, Tergas AI, Mateen FJ, Bhayani NH, Oh J (2013) Night-shift work and risk of breast cancer: a systematic review and meta-analysis. Breast Cancer Res Treat 138:291–301PubMedCrossRefGoogle Scholar
  10. 10.
    Ijaz SI, Verbeek JH, Seidler A et al (2013) Night-shift work and breast cancer—a systematic review and meta-analysis. Scand J Work Environ Health 39:431–447PubMedCrossRefGoogle Scholar
  11. 11.
    Papantoniou K, Kogevinas M (2013) Shift work and breast cancer: Do we need more evidence and what should this be? Occup Environ Med 70:825–826PubMedCrossRefGoogle Scholar
  12. 12.
    Jia Y, Lu Y, Wu K et al (2013) Does night work increase the risk of breast cancer? A systematic review and meta-analysis of epidemiological studies. Cancer Epidemiol 37:197–206PubMedCrossRefGoogle Scholar
  13. 13.
    Thomas DB, Gao DL, Ray RM et al (2002) Randomized trial of breast self-examination in Shanghai: final results. J Natl Cancer Inst 94:1445–1457PubMedCrossRefGoogle Scholar
  14. 14.
    Li W, Ray RM, Gao DL et al (2006) Occupational risk factors for nasopharyngeal cancer among female textile workers in Shanghai, China. Occup Environ Med 63:39–44PubMedCentralPubMedCrossRefGoogle Scholar
  15. 15.
    Ray RM, Gao DL, Li W et al (2007) Occupational exposures and breast cancer among women textile workers in Shanghai. Epidemiology 18:383–392PubMedCrossRefGoogle Scholar
  16. 16.
    Astrakianakis G, Seixas NS, Ray R et al (2007) Lung cancer risk among female textile workers exposed to endotoxin. J Natl Cancer Inst 99:357–364PubMedCrossRefGoogle Scholar
  17. 17.
    Wernli KJ, Ray RM, Gao DL, Thomas DB, Checkoway H (2003) Cancer among women textile workers in Shanghai, China: overall incidence patterns, 1989–1998. Am J Ind Med 44:595–599PubMedCrossRefGoogle Scholar
  18. 18.
    Thomas DB, Gao DL, Self SG et al (1997) Randomized trial of breast self-examination in Shanghai: methodology and preliminary results. J Natl Cancer Inst 89:355–365PubMedCrossRefGoogle Scholar
  19. 19.
    Li W, Ray RM, Lampe JW et al (2005) Dietary and other risk factors in women having fibrocystic breast conditions with and without concurrent breast cancer: a nested case–control study in Shanghai, China. Int J Cancer 115:981–993Google Scholar
  20. 20.
    Ye Z, Gao DL, Qin Q, Ray RM, Thomas DB (2002) Breast cancer in relation to induced abortions in a cohort of Chinese women. Br J Cancer 87:977–981PubMedCentralPubMedCrossRefGoogle Scholar
  21. 21.
    Langholz B, Jiao J (2007) Computational methods for case–cohort studies. Comput Stat Data Anal 51:3737–3748CrossRefGoogle Scholar
  22. 22.
    Li W, Ray RM, Thomas DB et al (2013) Occupational exposure to magnetic fields and breast cancer among women textile workers in shanghai, china. Am J Epidemiol 178:1038–1045PubMedCentralPubMedCrossRefGoogle Scholar
  23. 23.
    O’Leary ES, Schoenfeld ER, Stevens RG et al (2006) Shift work, light at night, and breast cancer on Long Island, New York. Am J Epidemiol 164:358–366PubMedCrossRefGoogle Scholar
  24. 24.
    Davis S, Mirick DK, Stevens RG (2001) Night shift work, light at night, and risk of breast cancer. J Natl Cancer Inst 93:1557–1562PubMedCrossRefGoogle Scholar
  25. 25.
    Hansen J (2001) Increased breast cancer risk among women who work predominantly at night. Epidemiology 12:74–77PubMedCrossRefGoogle Scholar
  26. 26.
    Hansen J, Stevens RG (2012) Case–control study of shift-work and breast cancer risk in Danish nurses: impact of shift systems. Eur J Cancer 48:1722–1729PubMedCrossRefGoogle Scholar
  27. 27.
    Grundy A, Schuetz JM, Lai AS et al (2013) Shift work, circadian gene variants and risk of breast cancer. Cancer Epidemiol 37:606–612PubMedCrossRefGoogle Scholar
  28. 28.
    Schwartzbaum J, Ahlbom A, Feychting M (2007) Cohort study of cancer risk among male and female shift workers. Scand J Work Environ Health 33:336–343PubMedCrossRefGoogle Scholar
  29. 29.
    Tynes T, Hannevik M, Andersen A, Vistnes AI, Haldorsen T (1996) Incidence of breast cancer in Norwegian female radio and telegraph operators. Cancer Causes Control 7:197–204PubMedCrossRefGoogle Scholar
  30. 30.
    Mirick DK, Davis S (2008) Melatonin as a biomarker of circadian dysregulation. Cancer Epidemiol Biomark Prev 17:3306–3313CrossRefGoogle Scholar
  31. 31.
    Girschik J, Heyworth J, Fritschi L (2010) Re: “Night-shift work and breast cancer risk in a cohort of Chinese women”. Am J Epidemiol 172:865–866Google Scholar
  32. 32.
    Kayumov L, Lowe A, Rahman SA, Casper RF, Shapiro CM (2007) Prevention of melatonin suppression by nocturnal lighting: relevance to cancer. Eur J Cancer Prev 16:357–362PubMedCrossRefGoogle Scholar
  33. 33.
    Higuchi S, Motohashi Y, Ishibashi K, Maeda T (2007) Influence of eye colors of Caucasians and Asians on suppression of melatonin secretion by light. Am J Physiol Regul Integr Comp Physiol 292:R2352–R2356PubMedCrossRefGoogle Scholar

Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  • Wenjin Li
    • 1
  • Roberta M. Ray
    • 1
  • David B. Thomas
    • 1
  • Scott Davis
    • 1
    • 6
  • Michael Yost
    • 2
  • Norman Breslow
    • 1
    • 3
  • Dao Li Gao
    • 4
  • E. Dawn Fitzgibbons
    • 5
  • Janice E. Camp
    • 2
  • Eva Wong
    • 6
  • Karen J. Wernli
    • 5
  • Harvey Checkoway
    • 2
    • 7
  1. 1.Program in EpidemiologyFred Hutchinson Cancer Research CenterSeattleUSA
  2. 2.Department of Environmental and Occupational Health SciencesUniversity of WashingtonSeattleUSA
  3. 3.Department of BiostatisticsUniversity of WashingtonSeattleUSA
  4. 4.Department of EpidemiologyZhong Shan Hospital BranchShanghaiChina
  5. 5.Group Health Research InstituteSeattleUSA
  6. 6.Department of EpidemiologyUniversity of WashingtonSeattleUSA
  7. 7.Department of Family and Preventive MedicineUniversity of CaliforniaSan DiegoUSA

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