Table 3.
Risk of breast cancer in relation to YEARS worked on rotating night shift for two groups of women divided by age.
| Cumulative exposure (years) | Cases | HRa | 95% CI |
|---|---|---|---|
| women < 50 years old (732 cases) | |||
| Entire employment period | |||
| 0 | 273 | 1.00 | (ref) |
| >0-11.0 | 114 | 0.87 | (0.67, 1.12) |
| >11.0-16.8 | 118 | 0.94 | (0.73, 1.22) |
| >16.8-21.54 | 112 | 1.06 | (0.81, 1.37) |
| >21.54 | 115 | 0.94 | (0.72, 1.22) |
| p-value for trend* | 0.453 | ||
| 10-year lag | |||
| 0 | 292 | 1.00 | (ref) |
| >0-11.0 | 239 | 0.89 | (0.73, 1.10) |
| >11.0-16.8 | 125 | 1.02 | (0.80, 1.31) |
| >16.8-21.54 | 69 | 1.07 | (0.78, 1.46) |
| >21.54 | 7 | 0.88 | (0.39, 1.99) |
| p-value for trend | 0.344 | ||
| 20-year lagc | |||
| 0 | 437 | 1.00 | (ref) |
| >0-11.0 | 280 | 1.02 | (0.84, 1.25) |
| >11.0-16.8 | 15 | 0.98 | (0.55, 1.73) |
| p-value for trend | 0.896 | ||
| Women ≥ 50 years old (977 cases) | |||
| Entire employment period | |||
| 0 | 284 | 1.00 | (ref) |
| >0-14.5 | 173 | 1.23 | (0.97, 1.56) |
| >14.5-24.2 | 173 | 0.86 | (0.68, 1.09) |
| >24.2-31.17 | 174 | 0.85 | (0.67, 1.07) |
| >31.17 | 173 | 0.96 | (0.76, 1.23) |
| p-value for trend* | 0.430 | ||
| 10-year lag | |||
| 0 | 285 | 1.00 | (ref) |
| >0-14.5 | 177 | 1.22 | (0.97, 1.55) |
| >14.5-24.2 | 201 | 0.84 | (0.67, 1.06) |
| >24.2-31.17 | 156 | 0.87 | (0.68, 1.10) |
| >31.17 | 158 | 0.97 | (0.75, 1.25) |
| p-value for trend | 0.015 | ||
| 20-year lag | |||
| 0 | 288 | 1.00 | (ref) |
| >0-14.5 | 268 | 1.06 | (0.86, 1.30) |
| >14.5-24.2 | 225 | 0.91 | (0.73, 1.13) |
| >24.2-31.17 | 156 | 0.91 | (0.71, 1.18) |
| >31.17 | 40 | 0.88 | (0.59, 1.33) |
| p-value for trend | 0.015 |