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Table 2 Case-control studies of night work and breast cancer

From: The relationship between night work and breast cancer

Authors, (years)
Country
Study description Exposure
Assessment
Exposure
categories
Odds ratio
Tynes et al.
(1996) [27]
Norway
Nested case-control study of a cohort of 2619 female radio and telegraph operators enrolled 1920–1980, with follow-up 1961–1991; 50 cases and 4–7 matched (year of birth) controls Collected detailed job histories from Norwegian seamen registry; “Work at night with exposure to artificial light?” From cases and controls, detailed information on job histories on ships, as well as shift work and travel through time zones was collected Aged < 50  
None 1.0 (ref)
<  3.1 years. 0.3 (0.1–1.2)
>  3.1 years 0.9 (0.3–2.9)
P for trend 0.97
Aged 50+  
None 1.0 (ref)
<  3.1 years 3.2 (0.6–17.3)
>  3.1 years 4.3 (0.7–26.0)
P for trend 0.13
Hansen
(2001) [20]
Denmark
Nested case-control study with
follow-up 1964–1999; 7565 cases and 1:1 matched controls (year of birth and sex)
Individual employment histories were obtained from files of national pension funds All night work combined in trades with > 60% night work 1.5 (1.3–1.7)
Employed > 6 years 1.7 (1.3–1.7)
Nurses 1.3 (1.1–1.4)
Davis et al.
(2001) [21]
USA
Cancer register-based case–control study; 813 cases (1992–1995) and 793 matched (5-year age groups) controls identified by random-digit dialing Information on sleeping habits, light exposure, lifetime occupational history obtained from in-person interviews; night workers defined if ≥1 graveyard shift/wk. (8 h) in 10 years before diagnosis of cancer Years worked
3 nights/wk.
 
None 1.0 (ref)
<  1 1.2 (0.6–2.3)
1–3 1.4 (0.7–2.8)
3–4.6 0.6 (0.3–1.5)
4.7+ 2.3 (1.2–4.2)
P for trend 0.01
Lie et al.
(2006) [22]
Norway
Nested case-control study of the cohort of 44,835 Norwegian nurses; 537 cases (1960–1982) and 1:4 matched (year of birth) controls Total work history reconstructed from occupational information for nurses from the registry censuses of the Norwegian Board of Health in 1960, 1970, and 1980 Years night work  
0 1.0 (ref)
1–14 0.95 (0.67–1.33)
15–29 1.29 (0.82–2.02)
30+ 2.21 (1.10–4.45)
P for trend 0.01
O’Leary et al.
(2006) [29]
USA
Case-control study of 576 cases (1996–1997) and 585 1:1 matched (age in 5-year age groups) population-based controls Occupational history since age 16, and residential light-at-night exposures (e.g., sleep hours, frequency of turning on lights during night, length of time light was on) from in-person interviews Any evening or overnight shift work 1.04 (0.79–1.38)
Any evening shift work only 1.21 (0.90–1.64)
Any overnight shift work only 0.55 (0.32–0.94)
Pesch et al.
(2010) [30]
Germany
GENICA: a population-based case-control study conducted among women from the Greater Region of Bonn, Germany Night work was defined as working full-time between 24.00–05.00 h Never 1.0 (ref)
1–4 years 0.64 (0.34–1.24)
5–9 years 0.93 (0.41–2.15)
10–19 years 0.91 (0.38–2.18)
20 years and more 2.49 (0.87–7.18)
Lie et al.
(2011) [26]
Norway
Nested case-control study within a cohort of 49,402 female nurses;
699 cases and 895 controls
“Night work” includes working
periods in both rotating and permanent night schedules, and includes the work of permanent night workers
Never night work 1.0 (ref)
1–11 years 1.2 (0.9–1.5)
12 years 1.3 (0.9–1.8)
P for trend 0.17
Hansen et al.
(2012) [23]
Denmark
Nested case-control study within a nationwide cohort of Danish nurses (N = 91,140), including detailed information on lifetime shift-work and potential confounders Information on shift work obtained from interviews; Day work defined as working from 6 or 7 to 15 or 16, evening work from 15 or 16 to 23 or 24, and night work from 23 or 24 to 7 or 8 Day-evening only 1.0 (ref)
1–4 years of night work 1.5 (0.99–2.5)
5–9 2.3 (1.4–3.5)
10–19 1.9 (1.1–2.8)
≥ 20 2.1 (1.3–3.2)
Hansen et al.
(2012) [24]
Denmark
Nationwide case-control study
nested within a cohort of 18,551 female military employees born in 1929–1968
Information on shift work, sun exposure habits, diurnal preferences, and other potential confounders Never 1.0 (ref)
1–5.9 years 0.9 (0.4–1.7)
6–14.9 years 1.7 (0.9–3.2)
15 years and more 2.1 (1.0–4.5)
P for trend 0.06
Fritschi et al.
(2013) [28]
Australia
Case control study of cases from the population-based Western Australian (WA) Cancer Registry, with 1205 incident cases and 1789 frequency age-matched controls Information on shift work obtained from telephone interviews, with levels of night work being
high: job involved > 4 nights forward rotation or > 6 nights backward rotation, medium: 3–4 nights forward or 4–6 nights backward rotation, or low: 3 nights backward rotation
No rotation
Ever
<  10 years
10–20 years
>  20 years
1.0 (ref)
1.16 (0.97–1.38)
1.25 (1.00–1.56)
1.09 (0.79–1.50)
1.02 (0.71–1.45)
Grundy et al.
(2013) [25]
Canada
A case-control study
from 2005 to 2010
Case definition: where ≥50% of time was reported to have been spent on evening and/or night shifts, capturing both rotating and permanent night shift schedules No shifts 1.0 (ref)
0–14 years 0.95 (0.79–1.16)
15–29 years 0.93 (0.67–1.30)
>  30 years 2.21 (1.14–4.31)
Menegaux et al.
(2013) [31]
France
Population-based case-control study with 1232 cases of breast cancer and 1317 population controls Information on shift work obtained from in-person interviews;
Overnight: night shift of 6 consecutive work hours or more spanning the time period 11 pm–5 am
Never 1.0 (ref)
<  4.5 years 1.27 (0.83–1.94)
4.5 years and more 1.40 (0.96–2.04)
Li et al.
(2015) [32]
China
An extension of a series of case-cohort studies of textile industry exposures to dusts, chemicals, and other physical agents in relation to risks of various cancers Night work was defined as continuous work between 24:00 and 05:00  Day workers 1.0 (ref)
3 times/month 1.4 (0.8–2.6)
1–14 years 1.2 (0.9–1.6)
15–29 years 1.2 (0.9–1.7)
>  30 years 0.8 (0.5–1.4)
Papantoniou et al.
(2015) [33]
Spain
Population-based case-control study with 1708 breast cancer cases and 1778 population controls from 10 Spanish regions Lifetime occupational history was assessed by face-to-face interviews Never night work 1 (ref)
Ever night work 1.18 (0.97, 1.43)
Permanent 1.19 (0.89, 1.60)
Rotating 1.17 (0.91, 1.51)