Table 2 Summary risk ratios (RRs) and 95% confidence interval (CI) for the association between breast cancer risk and light at night exposure comparing the highest versus the lowest exposure categories for overall study population, outdoor and indoor exposure with selected subgroups
From: Light at night and risk of breast cancer: a systematic review and dose–response meta-analysis
Breast cancer | All studies | Outdoor | Indoor | ||||||
|---|---|---|---|---|---|---|---|---|---|
n | RR (95% CI) | I2 (%) | n | RR (95% CI) | I2 (%) | n | RR (95% CI) | I2 (%) | |
All women | 17 | 1.11 (1.07–1.15) | 0.0 | 7 | 1.11 (1.07–1.16) | 0.0 | 11 | 1.08 (1.00–1.17) | 6.5 |
Study design | |||||||||
Cohort/case-cohort studies | 9 | 1.11 (1.07–1.15) | 0.0 | 8 | 1.11 (1.07–1.16) | 0.0 | 4 | 1.05 (0.96–1.15) | 0. 0 |
Case–control studies | 8 | 1.11 (0.97–1.28) | 31.5 | 1 | 0.95 (0.71–1.28) | - | 7 | 1.14 (0.98–1.34) | 34.2 |
Menopausal status | |||||||||
Premenopausal | 8 | 1.16 (1.04–1.28) | 2.3 | 4 | 1.22 (1.08–1.39) | 0.0 | 4 | 1.04 (0.88–1.23) | 0.0 |
Postmenopausal | 9 | 1.07 (1.02–1.13) | 0.0 | 5 | 1.07 (1.00–1.14) | 5.9 | 4 | 1.08 (0.95–1.23) | 4.3 |
BMI | |||||||||
< 25 kg/m2 | 2 | 1.17 (1.00–1.36) | 38.9 | 2 | 1.17 (1.00–1.36) | 39.0 | - | – | - |
≥ 25 kg/m2 | 2 | 1.07 (0.87–1.32) | 53.8 | 2 | 1.07 (0.87–1.32) | 53.8 | - | – | – |
Estrogen receptor status | |||||||||
ER + | 7 | 1.09 (1.02–1.17) | 0.0 | 4 | 1.12 (0.95–1.32) | 44.8 | 3 | 1.06 (0.95–1.18) | 0.0 |
ER – | 7 | 1.07 (0.92–1.23) | 0.0 | 4 | 1.12 (0.92–1.35) | 0.0 | 3 | 1.01 (0.81–1.25) | 0.0 |
LAN/sunshine hours | |||||||||
< 2000 h | 3 | 0.99 (0.89–1.11) | 0.0 | 2 | 0.96 (0.80–1.16) | 0.0 | 1 | 1.01 (0.88–1.15) | – |
2000–3000 h | 11 | 1.12 (1.08–1.17) | 0.0 | 5 | 1.12 (1.07–1.17) | 0.0 | 7 | 1.13 (1.02–1.25) | 0.0 |
> 3000 h | 3 | 1.30 (1.11–1.52) | 15.4 | 1 | 1.47 (1.00–2.17) | – | 3 | 1.11 (0.79–1.56) | 66.3 |
Equinoctial UVB | |||||||||
0.0–0.58 W/m2 | 3 | 0.97 (0.87–1.08) | 0 .0 | 2 | 0.91 (0.76–1.09) | 0.0 | 1 | 1.01 (0.88–1.15) | – |
0.58–1.15 W/m2 | 1 | 1.27 (0.89–1.82) | – | 1 | 1.47 (1.00–2.17) | – | 1 | 1.01 (0.60–1.70) | – |
1.15–1.73 W/m2 | 13 | 1.15 (1.10–1.19) | 5.6 | 5 | 1.12 (1.07–1.17) | 0.0 | 9 | 1.20 (1.12–1.27) | 0.0 |