Table 2.
Risk of breast cancer in relation to YEARS worked on rotating night shift among textile workers in the Shanghai textile industry (1709 cases and 4780 non-cases).
| Cumulative exposure (years) | Cases | HRa | 95% CI |
|---|---|---|---|
| Entire employment periodb | |||
| 0 | 557 | 1.00 | (ref) |
| >0-12.8 | 286 | 0.99 | (0.83, 1.17) |
| >12.8-19.92 | 290 | 0.97 | (0.82, 1.15) |
| >19.92-27.67 | 289 | 0.90 | (0.76, 1.06) |
| >27.67 | 287 | 0.88 | (0.74, 1.05) |
| p-value for trend* | 0.095 | ||
| 10-year lag | |||
| 0 | 577 | 1.00 | (ref) |
| >0-12.8 | 431 | 0.98 | (0.84, 1.15) |
| >12.8-19.92 | 266 | 0.99 | (0.83, 1.17) |
| >19.92-27.67 | 200 | 0.81 | (0.67, 0.98) |
| >27.67 | 235 | 0.91 | (0.75, 1.10) |
| p-value for trend | 0.060 | ||
| 20-year lag | |||
| 0 | 725 | 1.00 | (ref) |
| >0-12.8 | 516 | 1.03 | (0.89, 1.20) |
| >12.8-19.92 | 180 | 0.90 | (0.74, 1.10) |
| >19.92-27.67 | 179 | 0.90 | (0.74, 1.11) |
| >27.67 | 109 | 0.88 | (0.68, 1.14) |
| p-value for trend | 0.035 |
a
Hazard ratios (HR) and 95% Confidence Interval (CI) adjusted for age at the beginning of follow-up (as a continuous variable)
b
Exposure were categorized based on the distribution of the entire employment period of the exposed cases
*
Trend tests were restricted to the exposed subjects. Cutpoints were determined based on the median values of each quartile.