Table 3.
Adjusted Hazard Ratiosa of Premenopausal Breast Cancer Incidence (1985–2013) in Relation to Cumulative Exposure to Metalworking Fluid Size <3.5μm (20-Year Lag) in Female Autoworkers in the UAW-GM Cohort Using Multiple Age Cut Points for Premenopausal Definition.
| Age at Diagnosis | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
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| Age 55 or Younger N = 3,263 (72 Cases) | Age 54 or Younger N = 3,211 (65 Cases) | Age 53 or Younger N = 3,148 (60 Cases) | Age 52 or Younger N = 3,092 (49 Cases) | |||||||||||||
|
|
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| Cumulative Exposure (mg/m3-years) | No. of Cases | Person-years | HR | 95% CI | No. of Cases | Person-years | HR | 95% CI | No. of Cases | Person-years | HR | 95% CI | No. of Cases | Person-years | HR | 95% CI |
|
| ||||||||||||||||
| Categorical | ||||||||||||||||
| Straight | ||||||||||||||||
| 0 | 54 | 48,105 | 1.00 | Referent | 48 | 46,151 | 1.00 | Referent | 45 | 44,131 | 1.00 | Referent | 39 | 42,082 | 1.00 | Referent |
| 0.0001–0.0799 | 9 | 5,470 | 0.95 | 0.36, 2.52 | 8 | 4,968 | 1.08 | 0.37, 3.10 | 7 | 4,488 | 0.82 | 0.26, 2.52 | 5 | 4,022 | 0.88 | 0.23, 3.31 |
| ≥0.0800 | 9 | 4,208 | 1.08 | 0.44, 2.66 | 9 | 3,692 | 1.47 | 0.56, 3.82 | 8 | 3,196 | 1.23 | 0.45, 3.37 | 5 | 2,728 | 1.15 | 0.34, 3.91 |
| P for trend | 0.89 | 0.41 | 0.54 | 0.80 | ||||||||||||
| Soluble | ||||||||||||||||
| 0 | 42 | 39,347 | 1.00 | Referent | 39 | 38,184 | 1.00 | Referent | 36 | 36,963 | 1.00 | Referent | 33 | 35,675 | 1.00 | Referent |
| 0.0001–0.3319 | 15 | 11,070 | 0.79 | 0.37, 1.71 | 14 | 10,189 | 0.81 | 0.36, 1.85 | 13 | 9,324 | 0.81 | 0.35, 1.89 | 9 | 8,488 | 0.60 | 0.22, 1.63 |
| ≥0.3320 | 15 | 7,366 | 0.83 | 0.33, 2.09 | 12 | 6,437 | 0.72 | 0.26, 2.00 | 11 | 5,529 | 0.76 | 0.27, 2.19 | 7 | 4,669 | 0.55 | 0.16, 1.88 |
| P for trend | 0.81 | 0.61 | 0.72 | 0.47 | ||||||||||||
| Synthetic | ||||||||||||||||
| 0 | 56 | 50,721 | 1.00 | Referent | 50 | 48,481 | 1.00 | Referent | 46 | 46,207 | 1.00 | Referent | 39 | 43,914 | 1.00 | Referent |
| 0.0001–0.0899 | 8 | 5,059 | 1.04 | 0.37, 2.96 | 8 | 4,601 | 1.16 | 0.39, 3.48 | 8 | 4,155 | 1.42 | 0.46, 4.39 | 5 | 3,725 | 1.33 | 0.34, 5.28 |
| ≥0.0900 | 8 | 2,003 | 2.40 | 0.88, 6.54 | 7 | 1,729 | 2.71 | 0.92, 7.98 | 6 | 1,453 | 2.78 | 0.88, 8.73 | 5 | 1,193 | 3.76 | 1.04, 13.51 |
| P for trend | 0.07 | 0.05 | 0.09 | 0.04 | ||||||||||||
| Continuous b | ||||||||||||||||
| Straight | 0.81 | 0.51, 1.27 | 0.87 | 0.57, 1.35 | 0.87 | 0.54, 1.39 | 0.82 | 0.42, 1.58 | ||||||||
| Soluble | 0.90 | 0.64, 1.27 | 0.91 | 0.59, 1.39 | 0.84 | 0.51, 1.38 | 0.75 | 0.39, 1.44 | ||||||||
| Synthetic | 1.06 | 0.95, 1.17 | 1.13 | 0.99, 1.30 | 1.15 | 1.00, 1.32 | 1.17 | 1.01, 1.35 | ||||||||
|
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Abbreviations: UAW-GM, United Autoworkers-General Motors; CI, confidence interval; HR, hazard ratio.
a
Each Cox regression models included cumulative exposure to the three fluid types, used age as time scale, and adjusted for year of hire, calendar year, race, and manufacturing plant.
b
HR per increase of one interquartile range among exposed subjects age 55 or younger; for the three fluid types these are 0.157, 0.474, and 0.092 mg/m3-years, respectively.