Table 2. Associations of Cigarette Smoking With Mortality After First Breast Cancer in the Women’s Circle of Health Follow-up Study.
| Characteristic | All-cause mortality | Breast cancer–specific mortality | ||||
|---|---|---|---|---|---|---|
| Person-years | Total deaths | HR (95% CI) | Person-years | Breast cancer deaths | HR (95% CI) | |
| Smoking statusa | ||||||
| Never smokers | 7897.2 | 168 | 1 [Reference] | 7897.2 | 102 | 1 [Reference] |
| Former smokers | 3261.5 | 82 | 1.25 (0.95-1.65) | 3261.5 | 41 | 1.22 (0.82-1.81) |
| Current smokers | 2094.2 | 80 | 1.52 (1.15-2.02) | 2094.2 | 42 | 1.27 (0.87-1.85) |
| No. of pack-years of smokinga | ||||||
| Never smokers | 7897.2 | 168 | 1 [Reference] | 7897.2 | 102 | 1 [Reference] |
| Former smokers | ||||||
| <10 | 1951.2 | 49 | 1.19 (0.86-1.65) | 1951.2 | 27 | 1.21 (0.77-1.89) |
| ≥10 | 1310.3 | 33 | 1.39 (0.94-2.05) | 1310.3 | 14 | 1.24 (0.67-2.31) |
| Current smokers | ||||||
| <10 | 886.4 | 23 | 1.06 (0.67-1.66) | 886.4 | 15 | 1.06 (0.62-1.81) |
| ≥10 | 1207.8 | 57 | 1.84 (1.34-2.53) | 1207.8 | 27 | 1.41 (0.88-2.26) |
| Duration of smoking, ya | ||||||
| Never smokers | 7897.2 | 168 | 1 [Reference] | 7897.2 | 102 | 1 [Reference] |
| Former smokers | ||||||
| <25 | 2244.4 | 48 | 1.08 (0.78-1.50) | 2244.4 | 24 | 1.01 (0.63-1.64) |
| ≥25 | 1017.1 | 34 | 1.67 (1.13-2.47) | 1017.1 | 17 | 1.87 (1.06-3.29) |
| Current smokers | ||||||
| <25 | 448.2 | 17 | 1.43 (0.85-2.42) | 448.2 | 8 | 0.80 (0.39-1.65) |
| ≥25 | 1645.9 | 63 | 1.56 (1.15-2.11) | 1645.9 | 34 | 1.48 (0.97-2.25) |
| Intensity of smokinga | ||||||
| Never smokers | 7897.2 | 168 | 1 [Reference] | 7897.2 | 102 | 1 [Reference] |
| Former smokers, cigarettes/d | ||||||
| <8 | 1583.4 | 41 | 1.22 (0.86-1.74) | 1583.4 | 22 | 1.26 (0.78-2.03) |
| ≥8 | 1678.1 | 41 | 1.28 (0.90-1.82) | 1678.1 | 19 | 1.17 (0.68-2.03) |
| Current smokers, cigarettes/d | ||||||
| <8 | 982.1 | 31 | 1.35 (0.91-2.02) | 982.1 | 19 | 1.34 (0.82-2.21) |
| ≥8 | 1112.1 | 49 | 1.65 (1.18-2.30) | 1112.1 | 23 | 1.21 (0.74-2.00) |
| Recency of cessationb | ||||||
| Never smokers | 6889.7 | 136 | 1 [Reference] | 6889.7 | 81 | 1 [Reference] |
| Current smokers | 1830.3 | 65 | 1.55 (1.15-2.10) | 1830.3 | 32 | 1.21 (0.79-1.84) |
| Former smokers, y | ||||||
| ≤10 | 856.3 | 23 | 1.40 (0.89-2.20) | 856.3 | 11 | 1.26 (0.63-2.51) |
| >10 | 1878.6 | 44 | 1.19 (0.84-1.70) | 1878.6 | 23 | 1.22 (0.74-2.00) |
Abbreviation: HR, hazard ratio.
a
Cox proportional hazards regression models adjusted for age at diagnosis, tumor stage, body mass index, alcohol consumption, educational level, household income, marital status, menopausal status, and physical activity. Competing risk models (Fine-Gray subdistribution hazard model) were used for breast cancer–specific mortality.
b
Cox proportional hazards regression models adjusted for age at diagnosis, tumor stage, waist-to-hip ratio, history of diabetes, history of hypertension, educational level, household income, and physical activity. Competing risk models (Fine-Gray subdistribution hazard model) were used for breast cancer–specific mortality.