Table 2 Characteristics of the selected (nested) case–control 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 | Sample size Case/control | Exposure data source | Adjusted confounders | Definition of night shift | NSW category | Quality score |
|---|---|---|---|---|---|---|
Hansen and Lassen [20] | 218/899 | Nationwide pension fund and Danish military’s company registration | HRT, number of childbirths, age at menarche, length of education, occasional sun-bathing, tobacco smoking status | Working during hours beginning after 17:00 and ending before 9:00 for at least 1 year, not including overtime | Short/long | High |
Hansen and Stevens [58] | 310/1240 | Danish nurses association | Age, family history of BC, MHT, number of mammograms | Graveyard shifts which worked after midnight (about 8Â h of work between 19 and 9) for at least 1Â year | Short/long | High |
Li et al. [21] | 1709/4780 | Factory records (80%), interviews (20%) | Parity, live births, BF, alcohol | Working at least once per week for at least 6Â months between midnight and 6 a.m | Short/long | Moderate |
Tynes et al. [55] | 50/259 | Telecom registry | Duration of employment, age, and age of first birth | Years on ships known to involve night shift work and cross time zones | Short/long | Moderate |
Linnersjo et al. [57] | 16/174 | Airline archives | None | ––- | Short | Moderate |
Rafnsson et al. [56] | 35/140 | Employment records | Age, age at first childbirth, live births | Employed full-time ≥ 5 years; frequent long distance flights due to remote Iceland location | Short | Moderate |
Hansen [61] | 6281/6024 | Nationwide Pension Fund | Age, age at first and last childbirth, parity, SES |  ≥ 6 months employment in a trade where ≥ 60% of randomly surveyed women worked at night | Short | High |
Fritschi et al. [22] | 1205/1789 | Western Australian (WA) Cancer Registry | Age, reproductive history, alcohol intake, smoking, PA and sleep, SES, remoteness of residence, family history of BC | Working for any number of hours between midnight and 0500Â h | Short/long | High |
Menegaux et al. [59] | 1232/1317 | French departments of ‘‘Coˆte d’Or’’ or ‘‘Ille-et-Vilaine’’ | Age, age at menarche, age at first full-term pregnancy, parity, MHT, family history of BC in first-degree relatives, BMI, alcohol consumption, and tobacco consumption | Working for at least 1 h between 11:00 pm and 5:00 am during all or part of each job | Short | High |
Grundy et al. [62] | 1034/1179 | BC Cancer Registry (Vancouver), Hotel Dieu Breast Assessment Program (Kingston) | Age, ethnicity; household income; education; menopausal status; use of fertility drugs, OC, non-steroidal anti-inflammatory drugs (NSAIDs), antidepressants and HRT; reproductive factors including ever having been pregnant, number of pregnancies, age at first birth, BF and age at first mammogram; family history of BC among first-degree relatives; lifestyle factors, including smoking status, pack-years smoking, lifetime alcohol consumption; and BMI |  ≥ 50% of time was reported to have been spent on evening and/or night shifts, capturing both rotating and permanent night shift schedules | Short/long | High |
Pesch et al. [65] | 857/892 | Telephone interview | Age, family history, HRT, Mammograms | Working the fulltime period between 24:00–05:00 h | Short/long | High |
O'Leary et al. [60] | 576/585 | In-person occupational history | Age, live births, family history, education, benign breast disease | Overnight shift which could start as early as 7:00 p.m. and continue until the following morning | Short | High |
Davis et al. [63] | 763/741 | In-person occupational interview | Parity, family history, OC use, recent HRT | Graveyard shift which began after 7:00 PM and leaving work before 9:00 AM | Short | High |
Papantoniou et al. [64] | 1708/1778 | MCC-Spain Study | Age, family history, education, marital status, BMI, Tobacco smoking, PA, sleep habits, diet habits, Menopausal status, Parity, age at first birth, BF, ever OC, ever hormonal therapy, past sun exposure | Night work was defined as a working schedule that involved partly or entirely working between 00:00 and 6:00 a.m. at least three nights per month. This definition included overnight, late evening (end after 00:00) and early morning (start before 6:00) shifts | Short/long | High |
Santi et al. [67] | 743/775 | Questionnaire | Age, family history, level of education, OC use, alcohol consumption, number of births, and age of first menstruation | Nurses were classified as night-shift workers if they worked in hospitals | Short/long | High |
Rabstein et al. [66] | 857/892 | GENICA (Gene–ENvironment Interaction and breast CAncer) | Family history of BC, HRT, number of mammograms, and estrogen receptor status | Ever having worked in night shifts for ≥ 1 year and working the fulltime period between 24:00–05:00 h | Short/long | High |
Lie et al. [68] | 172/474 | Cancer Registry of Norway | Age at diagnosis, period of diagnosis, parity, family history of BC in mother or sister, hormonal treatment in the previous 2Â years before diagnosis, and frequency of alcohol consumption at the time of diagnosis | Work between 12Â pm and 6 am | Short/long | High |
Truong et al. [16] | 1126/1174 | CECILE study | Age, study area, age at menarche, age at first full-term pregnancy, parity, MHT, BMI, alcohol consumption, and tobacco consumption | Work for at least 1Â h between 1100 and 0500Â h during all or part of each job period | Ever/short | High |
Pham et al. [69] | 1721/1721 | Questionnaire and face to face interview | Age, educational level, number of pregnancies, age at birth of first child, body mass index, age at menarche, alcohol consumption, smoking, use of female hormone treatment, and family history of breast cancer in first degree relatives | Ever having worked in night shifts regularly between 9:00Â pm and 8:00 am for at least 2Â months in their lifetime | Short/long | High |