Invasive breast cancer HRs and 95% CIs, by menopausal status, associated with any exposure and intensity-years of passive smoke exposure in the CTS
| Menopausal status* | n | No. cases | HR (95% CI) | HR (95% CI) |
|---|---|---|---|---|
| Adjusted for age and race | Adjusted for age, race, and personal risk factors† | |||
| Premenopausal at baseline | ||||
| Any exposure | ||||
| Lifetime exposure | ||||
| Never | 4,030 | 59 | 1.00 | 1.00 |
| Ever | 21,510 | 404 | 1.04 (0.79-1.38) | 1.04 (0.79-1.38) |
| Age-specific exposure | ||||
| Never | 4,030 | 59 | 1.00 | 1.00 |
| Ever exposed <age 20 | 17,636 | 324 | 0.96 (0.77-1.18) | 0.95 (0.77-1.18) |
| Ever exposed ≥age 20 | 16,259 | 307 | 0.96 (0.77-1.19) | 0.95 (0.77-1.19) |
| Intensity-years | ||||
| Lifetime exposure | ||||
| None | 4,030 | 59 | 1.00 | 1.00 |
| Low (≤17.5) | 9,686 | 176 | 1.11 (0.83-1.50) | 1.11 (0.82-1.49) |
| Medium (17.6-42.0) | 6,587 | 130 | 1.06 (0.77-1.44) | 1.06 (0.77-1.44) |
| High (>42.0) | 4,808 | 90 | 0.92 (0.66-1.28) | 0.92 (0.66-1.29) |
| Age-specific exposure | ||||
| None | 4,030 | 59 | 1.00 | 1.00 |
| Age <20 exposure | ||||
| Low (≤17.5) | 10,390 | 186 | 0.97 (0.77-1.22) | 0.96 (0.76-1.21) |
| Medium (17.6-42.0) | 4,788 | 95 | 1.02 (0.77-1.34) | 1.02 (0.78-1.36) |
| High (>42.0) | 2,019 | 31 | 0.77 (0.51-1.16) | 0.77 (0.51-1.16) |
| Age ≥20 exposure | ||||
| Low (≤17.5) | 11,528 | 208 | 0.98 (0.78-1.23) | 0.97 (0.77-1.22) |
| Medium (17.6-42.0) | 2,975 | 62 | 0.96 (0.69-1.32) | 0.95 (0.69-1.31) |
| High (>42.0) | 1,257 | 30 | 0.98 (0.64-1.50) | 0.98 (0.64-1.51) |
| Premenopausal at baseline and age <50 at follow-up‡ | ||||
| Any exposure | ||||
| Lifetime exposure | ||||
| Never | 2,235 | 32 | 1.00 | 1.00 |
| Ever | 7,843 | 160 | 0.89 (0.60-1.33) | 0.93 (0.61-1.41) |
| Age-specific exposure | ||||
| Never | 2,235 | 32 | 1.00 | 1.00 |
| Ever exposed <age 20 | 6,550 | 129 | 0.93 (0.65-1.31) | 1.02 (0.71-1.48) |
| Ever exposed ≥age 20 | 5,366 | 119 | 0.94 (0.66-1.32) | 0.90 (0.63-1.29) |
| Intensity-years | ||||
| Lifetime exposure | ||||
| None | 2,235 | 32 | 1.00 | 1.00 |
| Low (≤17.5) | 4,313 | 79 | 0.90 (0.58-1.40) | 0.91 (0.58-1.43) |
| Medium (17.6-42.0) | 2,226 | 44 | 0.75 (0.46-1.22) | 0.80 (0.48-1.34) |
| High (>42.0) | 1,190 | 33 | 1.13 (0.68-1.89) | 1.20 (0.70-2.05) |
| Age-specific exposure | ||||
| None | 2,235 | 32 | 1.00 | 1.00 |
| Age <20 exposure | ||||
| Low (≤17.5) | 4,109 | 69 | 0.82 (0.55-1.21) | 0.87 (0.57-1.31) |
| Medium (17.6-42.0) | 1,656 | 40 | 1.07 (0.67-1.70) | 1.20 (0.74-1.95) |
| High (>42.0) | 649 | 14 | 1.10 (0.57-2.13) | 1.15 (0.58-2.28) |
| Age ≥20 exposure | ||||
| Low (≤17.5) | 4,501 | 90 | 0.87 (0.61-1.25) | 0.80 (0.55-1.17) |
| Medium (17.6-42.0) | 660 | 18 | 1.00 (0.55-1.81) | 1.12 (0.60-2.07) |
| High (>42.0) | 89 | 6 | 1.15 (0.43-3.05) | 0.98 (0.34-2.79) |
| Postmenopausal at baseline | ||||
| Any exposure | ||||
| Lifetime exposure | ||||
| Never | 2,545 | 84 | 1.00 | 1.00 |
| Ever | 23,002 | 989 | 1.25 (1.00-1.57) | 1.22 (0.97-1.52) |
| Age-specific exposure | ||||
| Never | 2,545 | 84 | 1.00 | 1.00 |
| Ever exposed <age 20 | 15,857 | 688 | 1.12 (0.96-1.30) | 1.12 (0.97-1.31) |
| Ever exposed ≥age 20 | 20,774 | 910 | 1.15 (0.95-1.39) | 1.11 (0.92-1.34) |
| Intensity-years | ||||
| Lifetime exposure | ||||
| None | 2,545 | 84 | 1.00 | 1.00 |
| Low (≤17.5) | 6,281 | 251 | 1.19 (0.93-1.52) | 1.17 (0.91-1.49) |
| Medium (17.6-42.0) | 6,270 | 264 | 1.23 (0.96-1.57) | 1.19 (0.93-1.53) |
| High (>42.0) | 9,393 | 430 | 1.31 (1.03-1.65) | 1.26 (0.99-1.60) |
| Age-specific exposure | ||||
| None | 2,545 | 84 | 1.00 | 1.00 |
| Age <20 exposure | ||||
| Low (≤17.5) | 8,900 | 411 | 1.16 (0.99-1.37) | 1.17 (0.99-1.37) |
| Medium (17.6-42.0) | 4,168 | 161 | 0.95 (0.77-1.16) | 0.96 (0.78-1.18) |
| High (>42.0) | 1,654 | 77 | 1.13 (0.86-1.48) | 1.14 (0.87-1.50) |
| Age ≥20 exposure | ||||
| Low (≤17.5) | 7,768 | 325 | 1.15 (0.93-1.41) | 1.12 (0.91-1.37) |
| Medium (17.6-42.0) | 5,211 | 205 | 1.06 (0.84-1.32) | 1.02 (0.81-1.28) |
| High (>42.0) | 6,563 | 327 | 1.31 (1.05-1.62) | 1.25 (1.01-1.56) |
↵*There were too few cases in the perimenopausal group at baseline to include in these analyses.
↵†Personal risk factors include family history of breast cancer, age at menarche, pregnancy history, lifetime duration of breast-feeding, BMI, physical activity, alcohol consumption, and use of hormone therapy.
↵‡Premenopausal at baseline and follow-up includes women who were premenopausal at baseline and either diagnosed or censored before the age of 50.