Risk of invasive and borderline ovarian tumours, by age at reference date, in association with working the nightshift
| <50 years of age at reference date | ≥50 years of age at reference date | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Invasive | Borderline | Invasive | Borderline | |||||||
| Controls (%) (n=444) | Cases (%) (n=274) | OR* (95% CI) | Cases (%) (n=172) | OR* (95% CI) | Controls (%) (n=1388) | Cases (%) (n=827) | OR* (95% CI) | Cases (%) (n=217) | OR* (95% CI) | |
| Worked nightshift | ||||||||||
| Never | 326 (73.4) | 197 (71.9) | 113 (65.7) | 1094 (78.8) | 611 (78.8) | 150 (69.1) | ||||
| Ever | 118 (26.6) | 77 (28.1) | 1.0 (0.69 to 1.44) | 118 (26.6) | 1.38 (0.92 to 2.05) | 294 (21.2) | 216 (21.2) | 1.32 (1.07 to 1.63) | 67 (30.1) | 1.57 (1.13 to 2.19) |
| Cumulative nightshift work-years | ||||||||||
| Never | 326 (73.4) | 197 (71.9) | 113 (65.7) | 1094 (78.8) | 611 (73.9) | 150 (69.1) | ||||
| 4 months–1 year | 26 (5.9) | 16 (5.8) | 1.06 (0.52 to 2.15) | 12 (7.0) | 1.28 (0.61 to 2.71) | 71 (5.1) | 39 (4.7) | 0.98 (0.65 to 1.49) | 15 (6.9) | 1.51 (0.83 to 2.76) |
| >1–3 years | 44 (9.9) | 22 (8.0) | 0.82 (0.45 to 1.49) | 20 (11.6) | 1.28 (0.70 to 2.34) | 77 (5.6) | 53 (6.4) | 1.26 (0.89 to 1.84) | 15 (6.9) | 1.32 (0.73 to 2.40) |
| >3–7 years | 24 (5.4) | 28 (10.2) | 1.52 (0.81 to 2.87) | 22 (12.8) | 2.36 (1.22 to 4.57) | 61 (4.4) | 66 (8.0) | 2.04 (1.40 to 2.97) | 22 (10.1) | 2.34 (1.36 to 4.01) |
| >7 years | 24 (5.4) | 11 (4.0) | 0.67 (0.30 to 1.51) | 5 (2.9) | 0.63 (0.22 to 1.74) | 84 (6.1) | 57 (7.0) | 1.16 (0.80 to 1.66) | 15 (6.9) | 1.29 (0.71 to 2.33) |
| Unknown | 0 (0) | (0) (0) | – | 0 (0) | – | 1 (<1) | 1 (<1) | – | 0 (0) | – |
Reference date is the date of diagnosis among cases and a comparable assigned date among controls.
*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.