Shift work history and breast cancer risk
| Years shift work history* | Cases | Controls | OR | 95% CI | Interaction by menopausal status |
|---|---|---|---|---|---|
| n (%) | n (%) | ||||
| Overall† | |||||
| None | 751 (66.2) | 773 (65.6) | – | ||
| 0–14 | 283 (25.0) | 312 (26.5) | 0.95 | 0.79 to 1.16 | p=0.01 |
| 15–29 | 72 (6.3) | 81 (6.9) | 0.93 | 0.67 to 1.30 | p=0.7 |
| ≥30 | 28 (2.5) | 13 (1.1) | 2.21 | 1.14 to 4.31 | p=0.2 |
| p-trend=0.5 | |||||
| Postmenopausal‡ | |||||
| None | 531 (71.5) | 501 (68.3) | – | ||
| 0–14 | 142 (19.1) | 175 (23.8) | 0.75 | 0.58 to 0.97 | |
| 15–29 | 48 (6.5) | 46 (6.3) | 0.97 | 0.63 to 1.49 | |
| ≥30 | 22 (3.0) | 12 (1.6) | 1.63 | 0.80 to 3.35 | |
| p-trend=0.8 | |||||
| Premenopausal‡ | |||||
| None | 220 (56.3) | 272 (61.1) | – | ||
| 0–9 | 126 (32.2) | 119 (26.7) | 1.32 | 0.97 to 1.80 | |
| 10–19 | 27 (6.9) | 35 (7.9) | 0.99 | 0.57 to 1.70 | |
| ≥20 | 18 (4.6) | 19 (4.3) | 1.30 | 0.66 to 2.58 | |
| p-trend=0.3 | |||||
| Health occupations | |||||
| None | 62 (44.9) | 94 (5.0) | – | ||
| 0–14 | 38 (27.5) | 72 (34.4) | 0.80 | 0.48 to 1.33 | |
| 15–29 | 26 (18.8) | 37 (17.7) | 1.06 | 0.58 to 1.92 | |
| ≥30 | 12 (8.7) | 6 (2.9) | 3.11 | 1.10 to 8.77 | |
| Non-health occupations | |||||
| None | 689 (69.2) | 679 (70.0) | – | ||
| 0–14 | 245 (24.6) | 240 (24.7) | 1.04 | 0.84 to 1.29 | |
| 15–29 | 46 (4.6) | 44 (4.5) | 1.06 | 0.69 to 1.62 | |
| ≥30 | 16 (1.6) | 7 (0.7) | 2.25 | 0.92 to 5.52 | |
*Using 50% of time definition.
†Model adjusted for age and centre.
‡Model adjusted for age, centre and BMI.