Associations between night work indicators and prostate cancer risk
| Ever night work | Permanent night work | Rotating night work | ||||
| Cases (n=818) /controls (n=875) | OR*† | Cases (n=742) /controls (n=769) | OR*† | Cases (n=616) /controls (n=667) | OR*† | |
| Never night work | 532/556 | 1.0 (reference) | 532/556 | 1.0 (reference) | 532/556 | 1.0 (Rreference) |
| Ever night work | 286/319 | 0.97 (0.79 to 1.19) | 210/213 | 1.04 (0.82 to 1.32) | 84/111 | 0.81 (0.59 to 1.16) |
| Early morning shifts‡ | 97/119 | 0.87 (0.64 to 1.18) | 61/76 | 0.87 (0.60 to 1.25) | 36/43 | 0.84 (0.52 to 1.35) |
| Late evening shifts§ | 119/131 | 0.98 (0.74 to 1.30) | 69/66 | 1.10 (0.76 to 1.59) | 50/66 | 0.82 (0.55 to 1.23) |
| Overnight shifts¶ | 161/190 | 0.90 (0.70 to 1.16) | 108/122 | 0.92 (0.68 to 1.23) | 58/70 | 0.86 (0.59 to 1.26) |
| Total duration of night work (years) | ||||||
| <20 | 145/176 | 0.90 (0.70 to 1.17) | 102/107 | 1.02 (0.75 to 1.38) | 50/76 | 0.72 (0.49 to 1.07) |
| <10 | 87/113 | 0.86 (0.63 to 1.18) | 54/65 | 0.91 (0.62 to 1.35) | 39/53 | 0.79 (0.50 to 1.22) |
| 10–19 | 58/63 | 0.98 (0.66 to 1.44) | 48/42 | 1.17 (0.76 to 1.83) | 11/23 | 0.57 (0.27 to 1.21) |
| ≥20 | 141/143 | 1.05 (0.80 to 1.38) | 108/106 | 1.06 (0.78 to 1.44) | 34/35 | 0.99 (0.60 to 1.65) |
| 20–29 | 50/58 | 0.94 (0.63 to 1.42) | 39/48 | 0.87 (0.56 to 1.37) | 19/14 | 1.29 (0.62 to 2.68) |
| ≥30 | 91/85 | 1.12 (0.80 to 1.56) | 69/58 | 1.22 (0.83 to 1.79) | 15/21 | 0.78 (0.39 to 1.55) |
| p-trend | 0.37 | 0.26 | 0.46 | |||
| Total frequency of night work (number of cumulative nights) | ||||||
| <1314 | 132/159 | 0.90 (0.69 to 1.18) | 90/88 | 1.05 (0.76 to 1.46) | 54/82 | 0.71 (0.49 to 1.04) |
| ≥1314 | 154/160 | 1.04 (0.80 to 1.35) | 120/125 | 1.03 (0.77 to 1.38) | 30/29 | 1.08 (0.63 to 1.87) |
| p-trend | 0.94 | 0.89 | 0.92 | |||
| Number of consecutive nights | ||||||
| <6 | 144/173 | 0.90 (0.69 to 1.17) | 95/98 | 1.01 (0.74 to 1.39) | 58/83 | 0.77 (0.53 to 1.11) |
| ≥6 | 124/108 | 1.24 (0.93 to 1.67) | 93/76 | 1.33 (0.95 to 1.87) | 26/27 | 0.98 (0.55 to 1.74) |
| p-trend | 0.25 | 0.25 | 0.83 | |||
| Shift length (hours) | ||||||
| <8 | 18/46 | 0.44 (0.25 to 0.78) | 11/37 | 0.32 (0.16 to 0.64) | 3/9 | 0.42 (0.11 to 1.57) |
| 8 to 10 | 97/131 | 0.79 (0.59 to 1.07) | 23/30 | 0.86 (0.48 to 1.53) | 69/92 | 0.79 (0.56 to 1.12) |
| >10 | 54/38 | 1.57 (1.01 to 2.44) | 38/22 | 1.88 (1.08 to 3.26) | 12/10 | 1.29 (0.54 to 3.07) |
| p-trend | 0.94 | 0.29 | 0.28 | |||
| Direction of shift rotation | ||||||
| Forward | 55/71 | 0.82 (0.56 to 1.21) | ||||
| Backward | 11/13 | 0.85 (0.37 to 1.98) | ||||
| Forward and backward | 18/27 | 0.74 (0.40 to 1.39) | ||||
| Speed of shift rotation (days) | ||||||
| Short (≤3) | 13/16 | 0.80 (0.37 to 1.72) | ||||
| Intermediate (4–5) | 41/57 | 0.82 (0.53 to 1.26) | ||||
| Long (≥6) | 20/20 | 0.95 (0.49 to 1.83) | ||||
| Short/intermediate/long | 14/21 | 0.62 (0.28 to 1.37) | ||||
*Adjusted for age, family history of prostate cancer, race, education level.
†95% CI.
‡Shifts starting before 05:00.
§Shifts ending between 21:00 and 02:00.
¶Shifts running from at least 00:00 to 05:00.