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Table 3 Characteristics of the selected cohort studies on breast cancer and night-shift work

From: Night-shift work duration and breast cancer risk: an updated systematic review and meta-analysis

Author

Total size/cases sample size

Follow up length (years)

Exposure data source

Adjusted confounders

Definition of night shift

NSW category

Quality score (%)

Koppes [72]

285,723/2531

7

Labor Force Survey

Age, origin, children in the household, education, occupational group, contractual working hours, and job tenure

Work at nights, meaning between midnight and 6 am

Short/long

High

Pronk et al. [74]

73,049/717

9

In-person occupational history plus job exposure matrix

Age, age at first childbirth, parity, family history, education, work-related PA

Starting work after 10 PM at least 3 times a month for over 1 year

Short/long

High

Ã…kerstedt et al. [70]

13,656/463

12

Swedish Twin registry, with follow-up in the Swedish Cancer Registry

Age, education, parity, Tobacco use, BMI, PA, Alcohol consumption, coffee consumption, menopause status, hormone use, previous cancer, time to BC diagnosis

Working hours in nights at least now and then

Short/long

High

Wegrzyn [73]

78,516/5971

24

Nurses’ Health Study

Age, height, current BMI and BMI at age 18 years, adolescent body size, age at menarche and at first birth, parity, BF history, type of menopause, age at menopause, MHT use, duration of use of estrogen-only MHT, duration of use of combined estrogen and progesterone MHT, first-degree family history of BC, history of benign breast disease, alcohol consumption, PA level, and current mammography use

At least 3 nights/month in addition to days/evenings in that month

Short/long

High

Wegrzyn [73]

114,559/3570

24

Nurses’ Health Study II

Age, height, current BMI and BMI at age 18 years, adolescent body size, age at menarche and at first birth, parity, BF history, type of menopause, age at menopause, MHT use, duration of use of estrogen-only MHT, duration of use of combined estrogen and progesterone MHT, first-degree family history of BC, history of benign breast disease, alcohol consumption, PA level, and current mammography use

At least 3 nights/month in addition to days/evenings in that month

Short/long

High

Jones et al. [71]

102,869/2059

9.5

Generations Study

Alcohol use, parity, OC use, MHT use, and menopausal status

Any jobs that regularly involved work in the late evening or night (between 10 pm and 7 am)

Short/long

Moderate

Travis et al. [28]

522 246/ 4809

Established 1996 to 2001. Analyzed at December 2013

Million woman study

Age, SES, marital status, nulliparity, age at first birth, number of children, obesity, PA, alcohol consumption, smoking, first-degree relative with BC, OC use, MHT use, amount of sleep, take medication to sleep, more evening than morning type

Any time between midnight and 06:00 h, for at least 3 nights per month

Short/long

High

Travis et al. [28]

22,559/181

Recruited 1993–1999. Analyzed at December 2013

EPIC-Oxford study

Age, SES, marital status, nulliparity, age at first birth, number of children, obesity, PA, alcohol consumption, smoking, first-degree relative with BC, OC use, MHT use, amount of sleep, take medication to sleep, more evening than morning type

Any job lasting for at least one year, and occurring on a regular basis for at least one night per month or 12 nights per year

Ever/long

High

Sweeney et al. [75]

48,451/3191

Recruited 2003–2009. Analyzed at September 2017

Sister study cohort

Age, race/ethnicity, education, marital status and parity

1 h between 12:00 and 2:00 AM) for ≥ 2 years

Short/long

High

  1. NSW night shift work, PA physical activity, BMI body mass index, BC breast cancer, BF breastfeeding, MHT menopausal hormone therapy, SES socioeconomic status, OC oral contraceptive