Risk of invasive and borderline ovarian tumours in association with working the nightshift
| Invasive | Borderline | ||||
|---|---|---|---|---|---|
| Controls (%) (n=1832) | Cases (%) (n=1101) | OR* (95% CI) | Cases (%) (n=389) | OR* (95% CI) | |
| Worked nightshift | |||||
| Never | 1420 (77.5) | 808 (73.4) | 263 (67.6) | ||
| Ever | 412 (22.5) | 293 (26.6) | 1.24 (1.04 to 1.49) | 126 (32.4) | 1.48 (1.15 to 1.90) |
| Worked nightshift for less than half of all work days | |||||
| Never | 1587 (86.6) | 916 (83.2) | 312 (80.2) | ||
| Ever | 245 (13.4) | 185 (16.8) | 1.28 (1.03 to 1.59) | 77 (19.8) | 1.32 (0.98 to 1.78) |
| Worked nightshift for all work days | |||||
| Never | 1696 (92.6) | 1006 (91.4) | 351 (90.2) | ||
| Ever | 136 (7.4) | 95 (8.6) | 1.16 (0.87 to 1.55) | 38 (9.8) | 1.29 (0.87 to 1.92) |
| Cumulative nightshift work-years | |||||
| Never | 1420 (77.5) | 808 (73.4) | 263 (67.6) | ||
| 4 months–1 year | 97 (5.3) | 55 (5.0) | 1.03 (0.72 to 1.47) | 27 (6.9) | 1.44 (0.90 to 2.29) |
| >1–3 years | 121 (6.6) | 75 (6.8) | 1.13 (0.82 to 1.54) | 35 (9.0) | 1.33 (0.87 to 2.02) |
| >3–7 years | 85 (4.6) | 94 (8.5) | 1.95 (1.41 to 2.68) | 44 (11.3) | 2.37 (1.57 to 3.57) |
| >7 years | 108 (5.9) | 68 (6.2) | 1.02 (0.74 to 1.42) | 20 (5.1) | 0.97 (0.58 to 1.61) |
| Unknown | 1 (<1) | 1 (<1) | – | 0 (0) | – |
*Adjusted for age at reference, county, reference year, duration of oral contraceptive use, number of full term pregnancies and body mass index at age 30.