TY - JOUR
T1 - No association between night shiftwork and mammographic density
AU - El-Zaemey, Sonia
AU - Fritschi, Lin
AU - Heyworth, Jane
AU - Boyle, Terry
AU - Saunders, Christobel
AU - Wylie, Elizabeth
AU - Stone, Jennifer
N1 - Publisher Copyright:
© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.
PY - 2020/8/1
Y1 - 2020/8/1
N2 - Background Increased mammographic density is one of the strongest risk factors for breast cancer. Night shiftwork and its related factors, which include light at night, phase shift and sleep disruption, are believed to increase breast cancer risk however, their effects on mammographic density have barely been studied. Methods This study included 1821 women enrolled in the Breast Cancer Environment and Employment Study between 2009 and 2011. Mammographic density was measured using the Cumulus software program. The association of night shiftwork factors with square root transformed absolute dense area (DA) and percentage dense area (PDA) were modelled using linear regression adjusted for confounders. Results Ever doing graveyard shiftwork (between 24:00 and 05:00 hours) was not associated with PDA (β=-0.10; 95% CI -0.27 to 0.08)) and DA (β=-0.12; 95% CI -0.33 to 0.09)). No association was found between night shiftwork related factors (light at night, phase shift and sleep disturbance) with PDA or DA. Conclusions Shiftwork and its related factors are not associated with mammographic density. Using high-quality, comprehensive shiftwork data from a large population-based breast cancer case-control study, this study suggests that mammographic density does not play a role in the relationship between shiftwork and breast cancer risk.
AB - Background Increased mammographic density is one of the strongest risk factors for breast cancer. Night shiftwork and its related factors, which include light at night, phase shift and sleep disruption, are believed to increase breast cancer risk however, their effects on mammographic density have barely been studied. Methods This study included 1821 women enrolled in the Breast Cancer Environment and Employment Study between 2009 and 2011. Mammographic density was measured using the Cumulus software program. The association of night shiftwork factors with square root transformed absolute dense area (DA) and percentage dense area (PDA) were modelled using linear regression adjusted for confounders. Results Ever doing graveyard shiftwork (between 24:00 and 05:00 hours) was not associated with PDA (β=-0.10; 95% CI -0.27 to 0.08)) and DA (β=-0.12; 95% CI -0.33 to 0.09)). No association was found between night shiftwork related factors (light at night, phase shift and sleep disturbance) with PDA or DA. Conclusions Shiftwork and its related factors are not associated with mammographic density. Using high-quality, comprehensive shiftwork data from a large population-based breast cancer case-control study, this study suggests that mammographic density does not play a role in the relationship between shiftwork and breast cancer risk.
KW - cancer
KW - shift work
UR - http://www.scopus.com/inward/record.url?scp=85085751005&partnerID=8YFLogxK
U2 - 10.1136/oemed-2019-106315
DO - 10.1136/oemed-2019-106315
M3 - Article
C2 - 32467312
AN - SCOPUS:85085751005
SN - 1351-0711
VL - 77
SP - 564
EP - 567
JO - Occupational and Environmental Medicine
JF - Occupational and Environmental Medicine
IS - 8
ER -