Table 2. Subgroup analyses regarding smoking and mortality in breast cancer survivors between whole studied.
| Subgroup | BC Specific Mortality | All-Cause Mortality | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| N | HR (95% CI) | I2 (%) | Pheterogeneity | Pinteraction | N | HR (95% CI) | I2 (%) | Pheterogeneity | Pinteraction | |
| Sample sizea | ||||||||||
| > 2000 [12–19] | ||||||||||
| Intensity(cigarettes/day)b | 4 | 1.10 (1.04,1.17) | 0 | 0.90 | 0.96 | 4 | 1.15 (1.10,1.21) | 0 | 0.44 | 0.78 |
| Cumulative amount (pack-years)c | 6 | 1.09 (1.06,1.13) | 0 | 0.72 | 0.91 | 7 | 1.16 (1.11,1.21) | 78 | 0.00 | 0.57 |
| Duration (years)d | 4 | 1.03 (1.02,1.05) | 0 | 0.79 | 0.88 | 4 | 1.05 (1.04,1.07) | 58 | 0.07 | 0.92 |
| < 2000 [14–15] | ||||||||||
| Intensity(cigarettes/day)b | 3 | 1.09 (0.96,1.22) | 0 | 0.73 | - | 3 | 1.11 (1.00,1.23) | 0 | 0.46 | - |
| Cumulative amount (pack-years)c | 3 | 1.02 (0.89,1.17) | 54 | 0.12 | - | 2 | 1.01 (0.77,1.32) | 64 | 0.10 | - |
| Duration (years)d | 2 | 0.98 (0.94,1.03) | 0 | 0.84 | - | 2 | 1.01 (0.95,1.08) | 62 | 0.11 | - |
| Followed- up duration (years) | ||||||||||
| > 10 [12–16, 18, 20] | ||||||||||
| Intensity(cigarettes/day)b | 2 | 1.11 (1.03,1.20) | 0 | 0.33 | 0.88 | 2 | 1.11 (1.03,1.20) | 0 | 0.33 | 0.88 |
| Cumulative amount (pack-years)c | 4 | 1.09 (1.06,1.13) | 0 | 0.54 | 0.87 | 4 | 1.15 (1.08,1.24) | 88 | 0.00 | 1.00 |
| Duration (years)d | 2 | 1.04 (1.02,1.07) | 0 | 0.71 | 0.76 | 2 | 1.06 (1.03,1.09) | 77 | 0.04 | 0.66 |
| < 10 [17, 11–14, 21, 15] | ||||||||||
| Intensity(cigarettes /day)b | 5 | 1.16 (1.11,1.22) | 0 | 0.55 | - | 5 | 1.16 (1.11,1.22) | 0 | 0.55 | - |
| Cumulative amount (pack-years)c | 5 | 1.07 (1.01,1.14) | 23 | 0.27 | - | 5 | 1.15 (1.10,1.21) | 21 | 0.29 | - |
| Duration (years)d | 4 | 1.02 (1.01,1.04) | 18 | 0.30 | - | 4 | 1.04 (1.02,1.06) | 56 | 0.08 | - |
| Smoking status | ||||||||||
| Current [12, 16, 17, 15, 20–15] | ||||||||||
| Intensity(cigarettes/day)b | 5 | 1.10 (1.03,1.16) | 0 | 0.88 | 0.90 | 4 | 1.16 (1.10,1.23) | 0 | 0.47 | 0.42 |
| Cumulative amount (pack-years)c | 5 | 1.11 (1.07,1.15) | 0 | 0.80 | 0.30 | 3 | 1.20 (1.11,1.30) | 80 | 0.01 | 0.09 |
| Duration (years)d | 3 | 1.03 (1.02,1.05) | 0 | 0.61 | 0.30 | 2 | 1.05 (1.03,1.08) | 82 | 0.02 | 0.53 |
| Intensity(cigarettes/day)e | 5 | 1.21 (1.07,1.36) | 0 | 0.88 | 0.94 | 4 | 1.35 (1.21,1.51) | 0 | 0.45 | 0.44 |
| Cumulative amount (pack-years)f | 5 | 1.23 (1.14,1.33) | 0 | 0.79 | 0.32 | 3 | 1.44 (1.23,1.69) | 77 | 0.01 | 0.11 |
| Duration (years)g | 3 | 1.05 (1.03,1.08) | 0 | 0.50 | 0.56 | 2 | 1.09 (1.05,1.14) | 84 | 0.01 | 0.41 |
| Ever or former [13, 16, 18, 19, 8, 21] | ||||||||||
| Intensity(cigarettes/day)b | 2 | 1.11 (0.99,1.23) | 0 | 0.78 | - | 3 | 1.12 (1.05,1.20) | 0.0 | 0.48 | - |
| Cumulative amount (pack-years)c | 4 | 1.06 (0.99,1.14) | 35 | 0.20 | - | 6 | 1.12 (1.08,1.15) | 25 | 0.24 | - |
| Duration (years)d | 3 | 1.01 (0.98,1.05) | 30 | 0.24 | - | 4 | 1.04 (1.01,1.07) | 55 | 0.08 | - |
| Intensity(cigarettes/day)e | 2 | 1.22 (0.98,1.51) | 0 | 0.78 | - | 3 | 1.26 (1.11,1.43) | 0 | 0.48 | - |
| Cumulative amount (pack-years)f | 4 | 1.13 (0.98,1.31) | 33 | 0.21 | - | 6 | 1.25 (1.18,1.33) | 24 | 0.25 | - |
| Duration (years)g | 3 | 1.02 (0.96,1.09) | 39 | 0.19 | - | 4 | 1.06 (1.02,1.11) | 47 | 0.13 | - |
| Tumor stage | ||||||||||
| I–III [12, 5, 19] | ||||||||||
| Intensity(cigarettes/day)b | 1 | 1.11 (0.99,1.24) | / | / | 0.97 | 1 | 1.17 (1.06,1.29) | / | / | 0.88 |
| Cumulative amount (pack-years)c | 3 | 1.09 (1.06,1.13) | 1.2 | 0.36 | 0.99 | 4 | 1.18 (1.09,1.27) | 89 | 0.00 | 0.79 |
| Duration (years)d | 2 | 1.03 (1.01,1.06) | 0 | 0.67 | 0.94 | 2 | 1.07 (1.05,1.08) | 0 | 0.54 | 0.57 |
| IV [16, 17, 19–20, 15] | ||||||||||
| Intensity(cigarettes/day)b | 4 | 1.12 (1.01,125) | 0 | 0.90 | - | 3 | 1.13 (1.05,1.21) | 0.0 | 0.44 | - |
| Cumulative amount (pack-years)c | 4 | 1.09 (1.02,1.17) | 8 | 0.35 | - | 3 | 1.10 (1.01,1.20) | 41 | 0.19 | - |
| Duration (years)d | 2 | 1.02 (0.95,1.09) | 75 | 0.05 | - | 2 | 1.02 (0.96,1.08) | 74 | 0.05 | - |
| adjustment for alcohol | ||||||||||
| Yes [12, 16, 17, 19, 21] | ||||||||||
| Intensity cigarettes/day)b | 3 | 1.12 (1.02,1.22) | 0 | 0.80 | 0.68 | 3 | 1.14 (1.07,1.22) | 14 | 0.31 | 0.80 |
| Cumulative amount (pack-years)c | 4 | 1.13 (1.06,1.20) | 0 | 0.69 | 0.30 | 5 | 1.18 (1.10,1.25) | 78 | 0.00 | 0.27 |
| Duration (years)d | 3 | 1.04 (1.02,1.06) | 0.0 | 0.73 | 0.34 | 3 | 1.06 (1.04,1.08) | 54.8 | 0.11 | 0.24 |
| No [18, 11, 14–15] | ||||||||||
| Intensity (cigarettes/day)b | 4 | 1.09 (1.02,1.16) | 0.0 | 0.89 | - | 4 | 1.15 (1.09,1.22) | 0.0 | 0.50 | - |
| Cumulative amount (pack-years)c | 5 | 1.08 (1.05,1.20) | 15.8 | 0.31 | - | 4 | 1.12 (1.06,1.18) | 56.8 | 0.07 | - |
| Duration (years)d | 3 | 1.01 (0.98,1.05) | 44.5 | 0.17 | - | 3 | 1.03 (0.99,1.06) | 52.8 | 0.12 | - |
| adjustment for therapies | ||||||||||
| Yes [12, 13, 17, 15–14, 21] | ||||||||||
| Intensity (cigarettes/day)b | 5 | 1.09 (1.03,1.15) | 0.0 | 0.97 | 0.84 | 5 | 1.16 (1.11,1.22) | 0.0 | 0.55 | 0.83 |
| Cumulative amount (pack-years)c | 7 | 1.10 (1.05,1.14) | 9.5 | 0.36 | 0.90 | 7 | 1.17 (1.11,1.23) | 69.4 | 0 | 0.40 |
| Duration (years)d | 5 | 1.03 (1.02,1.04) | 4.3 | 0.38 | 0.80 | 5 | 1.05 (1.03,1.07) | 66.9 | 0.02 | 0.67 |
| No [16, 18, 20] | ||||||||||
| Intensity (cigarettes/day)b | 2 | 1.15 (1.02,1.30) | 0.0 | 0.89 | - | 2 | 1.11 (1.03,1.20) | 0.0 | 0.33 | - |
| Cumulative amount (pack-years)c | 2 | 1.08 (1.05,1.12) | 0.0 | 0.43 | - | 2 | 1.10 (1.07,1.13) | 0.0 | 0.79 | - |
| Duration (years)d | 1 | 1.05 (1.01,1.09) | / | / | - | 1 | 1.04 (1.02,1.06) | / | / | - |
| Adjustment for menopausal status | ||||||||||
| Yes [12, 13, 15–14] | ||||||||||
| Intensity (cigarettes/day)b | 3 | 1.10 (1.03,1.17) | 0.0 | 0.94 | 0.97 | 3 | 1.17 (1.11,1.23) | 0.0 | 0.72 | 0.97 |
| Cumulative amount (pack-years)c | 4 | 1.11 (1.05,1.18) | 15 | 0.32 | 0.81 | 5 | 1.18 (1.10,1.26) | 78.6 | 0.00 | 0.81 |
| Duration (years)d | 4 | 1.03 (1.02,1.04) | 9.8 | 0.34 | 0.90 | 4 | 1.05 (1.02,1.07) | 75.2 | 0.00 | 0.90 |
| No [16–18, 19, 20] | ||||||||||
| Intensity (cigarettes/day)b | 4 | 1.11 (1.01,1.21) | 0.0 | 0.77 | - | 4 | 1.12 (1.05,1.19) | 2.5 | 0.38 | - |
| Cumulative amount (pack-years)c | 5 | 1.08 (1.05,1.12) | 0.0 | 0.55 | - | 4 | 1.10 (1.07,1.13) | 0.0 | 0.88 | - |
| Duration (years)d | 2 | 1.03 (0.98,1.09) | 40 | 0.20 | - | 2 | 1.04 (1.02,1.06) | 0.0 | 0.77 | - |
Abbreviations: N, number of studies; CI, confidence interval; HR, hazard ratio.
a
number of BC patients.
b
for every 10 cigarettes/day increment.
c
for every 10 pack-years increment.
d
for every 10 years increment.
e
for every 20 cigarettes/day increment.
f
for every 20 pack-years increment.
g
for every 20 years increment.
-P for interaction is duplicated with corresponding subgroup.