Table V.
Light at night exposure and breast cancer risk by ER subtype, NIEHS Sister Study.
| Overall breast cancer | ER+ Invasive | ER− Invasive | ||||||
|---|---|---|---|---|---|---|---|---|
| Light at Night – Baseline Survey | Person-years N=375,925 | All breast cancer N=2,736 | Age-adjusted HR (95% CI) | Adjusted HR (95% CI) a | ER+ N=1,574 | Adjusted HR (95% CI) a | ER− N=281 | Adjusted HR (95% CI) a |
| Types of light while sleeping | ||||||||
| No light | 65,315 | 486 | 1 (referent) | 1 (referent) | 264 | 1 (referent) | 53 | 1 (referent) |
| Daylight | 10,283 | 65 | 0.87 (0.67, 1.13) | 0.87 (0.66, 1.15) | 41 | 1.05 (0.74, 1.5) | 8 | 1.04 (0.49, 2.21) |
| Light/television in room | 43,826 | 336 | 1.07 (0.93, 1.23) | 1.09 (0.93, 1.26) | 178 | 1.20 (0.97, 1.47) | 39 | 0.97 (0.61, 1.55) |
| Light outside the room | 127,897 | 936 | 0.99 (0.89, 1.10) | 1.01 (0.90, 1.13) | 543 | 1.11 (0.96, 1.3) | 101 | 1.01 (0.71, 1.43) |
| Nightlight | 246,940 | 1762 | 0.96 (0.87, 1.07) | 0.97 (0.87, 1.08) | 1,028 | 1.07 (0.93, 1.23) | 178 | 0.91 (0.66, 1.25) |
| When awakened at night, turns on light? | ||||||||
| Never wakes up or doesn’t turn on the light when | 331,131 | 2393 | 1 (referent) | 1 (referent) | 1,378 | 1 (referent) | 250 | 1 (referent) |
| Turns on light | 41,537 | 320 | 1.06 (0.95, 1.20) | 1.07 (0.95, 1.21) | 183 | 1.07 (0.91, 1.26) | 28 | 0.89 (0.59, 1.34) |
| Light already on | 2,673 | 18 | 0.89 (0.56, 1.41) | 0.86 (0.52, 1.40) | 11 | 0.88 (0.46, 1.70) | 2 | NE |
a
Adjusted for race, education, income, marital status, postmenopausal hormone use, use or oral contraceptives, alcohol consumption, age at menarche, parity, age at first birth, age at menopause, pack years of smoking, physical activity.