Table 4.
Association Between Night-Shift Work and Prostate Cancer Risk, by Tumor Aggressiveness, PROtEuS, Montreal, Quebec, Canada, 2005–2012
| Night-Shift Work Metric | No. of Controls | Low-Grade Prostate Cancer | High-Grade Prostate Cancer | ||||
|---|---|---|---|---|---|---|---|
| No. of Cases | ORa | 95% CI | No. of Cases | ORa | 95% CI | ||
| Never engaged in night-shift work | 1,548 | 1,127 | 1.00 | Referent | 326 | 1.00 | Referent |
| Ever engaged in night-shift work | 403 | 338 | 1.08 | 0.91, 1.28 | 101 | 1.07 | 0.82, 1.39 |
| Cumulative duration of night-shift work, years | |||||||
| ≤4.00 | 106 | 93 | 1.08 | 0.81, 1.44 | 27 | 1.17 | 0.73, 1.87 |
| 4.01–11.00 | 112 | 83 | 0.98 | 0.72, 1.34 | 28 | 1.08 | 0.69, 1.68 |
| 11.01–21.00 | 87 | 81 | 1.20 | 0.87, 1.66 | 24 | 1.09 | 0.68, 1.75 |
| >21.00 | 98 | 81 | 1.08 | 0.79, 1.47 | 22 | 0.91 | 0.56, 1.48 |
| P for trend | 0.49 | 0.88 | |||||
| Intensity of night-shift work, nights/year | |||||||
| ≤83.33 | 97 | 85 | 1.12 | 0.83, 1.52 | 23 | 1.03 | 0.63, 1.67 |
| 83.34–122.50 | 106 | 106 | 1.25 | 0.94, 1.66 | 27 | 1.03 | 0.66, 1.61 |
| 122.51–240.00 | 103 | 71 | 0.90 | 0.65, 1.24 | 21 | 0.95 | 0.58, 1.56 |
| >240.00 | 97 | 76 | 1.03 | 0.75, 1.43 | 30 | 1.25 | 0.80, 1.94 |
| P for trend | 0.83 | 0.56 | |||||
| Cumulative no. of night shifts | |||||||
| ≤588 | 101 | 94 | 1.10 | 0.83, 1.47 | 25 | 1.11 | 0.68, 1.82 |
| 589–1,332 | 100 | 85 | 1.14 | 0.84, 1.56 | 31 | 1.37 | 0.88, 2.12 |
| 1,333–2,575 | 101 | 91 | 1.15 | 0.85, 1.56 | 24 | 0.95 | 0.60, 1.52 |
| >2,575 | 101 | 68 | 0.90 | 0.65, 1.26 | 21 | 0.83 | 0.50, 1.36 |
| P for trend | 0.83 | 0.72 | |||||
| Permanent night-shift work without rotation | 7 | 10 | 1.27 | 0.78, 2.09 | 2 | 1.02 | 0.46, 2.25 |
| Night-shift work with rotation | |||||||
| Never | 170 | 140 | 1.06 | 0.83, 1.36 | 52 | 1.29 | 0.92, 1.83 |
| Ever | 233 | 198 | 1.09 | 0.88, 1.34 | 49 | 0.90 | 0.64, 1.28 |
| Cumulative duration of night-shift work with rotation, years | |||||||
| ≤4.00 | 67 | 49 | 0.93 | 0.65, 1.35 | 10 | 0.77 | 0.39, 1.52 |
| 4.01–11.00 | 63 | 48 | 1.02 | 0.69, 1.51 | 16 | 1.10 | 0.62, 1.94 |
| 11.01–21.00 | 46 | 46 | 1.19 | 0.78, 1.80 | 10 | 0.85 | 0.43, 1.69 |
| >21.00 | 57 | 55 | 1.29 | 0.88, 1.89 | 13 | 0.91 | 0.49, 1.69 |
| P for trend | 0.38 | 0.51 | |||||
| Intensity of night-shift work with rotation, nights/year | |||||||
| ≤81.67 | 68 | 67 | 1.22 | 0.86, 1.73 | 14 | 0.89 | 0.48, 1.65 |
| 81.68–84.00 | 51 | 49 | 1.16 | 0.77, 1.73 | 14 | 1.07 | 0.59, 1.93 |
| 84.01–125.00 | 65 | 50 | 1.02 | 0.68, 1.52 | 12 | 0.77 | 0.40, 1.50 |
| >125.00 | 49 | 32 | 0.93 | 0.58, 1.50 | 9 | 0.90 | 0.44, 1.86 |
| P for trend | 0.92 | 0.38 | |||||
| Cumulative no. of night shifts with rotation | |||||||
| ≤490 | 59 | 49 | 1.00 | 0.68, 1.48 | 12 | 0.94 | 0.49, 1.83 |
| 491–1,111 | 57 | 48 | 1.16 | 0.77, 1.74 | 12 | 0.94 | 0.48, 1.82 |
| 1,112–2,292 | 59 | 52 | 1.08 | 0.74, 1.59 | 16 | 1.04 | 0.59, 1.82 |
| >2,292 | 58 | 49 | 1.13 | 0.75, 1.70 | 9 | 0.68 | 0.33, 1.40 |
| P for trend | 0.17 | 0.48 | |||||
| Direction of shift rotation | |||||||
| Always forward | 131 | 122 | 1.25 | 0.95, 1.63 | 36 | 1.18 | 0.80, 1.76 |
| Always backward | 3 | 1 | 0.36 | 0.04, 3.51 | 0 | ||
| Both | 78 | 59 | 1.05 | 0.73, 1.49 | 10 | 0.55 | 0.28, 1.07 |
| Not classifiable | 21 | 16 | 1.03 | 0.53, 2.02 | 3 | 0.63 | 0.19, 2.15 |
| Rate of shift rotation | |||||||
| Daily or 2–4 days/week | 12 | 18 | 2.10 | 0.99, 4.47 | 1 | 0.39 | 0.05, 3.01 |
| Weekly | 171 | 130 | 1.02 | 0.79, 1.30 | 39 | 0.97 | 0.66, 1.41 |
| More than weekly | 28 | 34 | 1.61 | 0.96, 2.70 | 5 | 0.75 | 0.29, 2.70 |
| Not classifiable | 22 | 16 | 0.98 | 0.51, 1.91 | 4 | 0.79 | 0.27, 2.33 |
| No. of night shifts with rotation | |||||||
| 0 (no rotation) | 170 | 140 | 1.06 | 0.83, 1.36 | 52 | 1.29 | 0.92, 1.83 |
| 2 | 90 | 66 | 0.95 | 0.68, 1.34 | 14 | 0.70 | 0.38, 1.27 |
| 3 | 143 | 132 | 1.17 | 0.90, 1.53 | 35 | 1.03 | 0.69, 1.54 |
Abbreviations: CI, confidence interval; OR, odds ratio; PROtEuS, Prostate Cancer and Environment Study.
a ORs were adjusted for age, ancestry, and education and based on the imputed data for night-shift work metrics (8%).