Table 5.
Association of cumulative secondhand smoke (SHS) exposure and lifetime pack-years active smoking (pkyrs) with breast tumor DNA methylation, postmenopausal cases, WEB study
| Secondhand smoke | Active smoking | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| SHS | N | ORa | 95% CI | Pkyrs | N | ORa | 95% CI | ||
| >M | <M | >M | <M | ||||||
| SFN | |||||||||
| None | 10 | 8 | 1.00 | (referent) | None | 63 | 66 | 1.00 | (referent) |
| ≤30 | 24 | 28 | 0.67 | (0.23; 2.00) | ≤18.9 | 30 | 38 | 0.82 | (0.45; 1.49) |
| >30 | 29 | 30 | 0.78 | (0.27; 2.30) | >18.9 | 38 | 35 | 1.12 | (0.63; 1.99) |
| SCGB3A1 | |||||||||
| None | 10 | 6 | 1.00 | (referent) | None | 54 | 68 | 1.00 | (referent) |
| ≤30 | 20 | 33 | 0.33 | (0.10; 1.08) | ≤18.9 | 30 | 35 | 1.10 | (0.59; 2.05) |
| >30 | 24 | 29 | 0.46 | (0.14; 1.47) | >18.9 | 32 | 41 | 1.05 | (0.57; 1.91) |
| RARB | |||||||||
| None | 8 | 11 | 1.00 | (referent) | None | 59 | 80 | 1.00 | (referent) |
| ≤30 | 29 | 35 | 1.14 | (0.40; 3.20) | ≤18.9 | 34 | 44 | 1.04 | (0.59; 1.82) |
| >30 | 21 | 34 | 0.86 | (0.30; 2.48) | >18.9 | 37 | 49 | 1.01 | (0.59; 1.75) |
| GSTP1 | |||||||||
| None | 9 | 7 | 1.00 | (referent) | None | 63 | 75 | 1.00 | (referent) |
| ≤30 | 34 | 27 | 1.03 | (0.34; 3.14) | ≤18.9 | 36 | 38 | 1.16 | (0.65; 2.04) |
| >30 | 31 | 29 | 1.20 | (0.39; 3.65) | >18.9 | 42 | 36 | 1.42 | (0.81; 2.49) |
| CDKN2A | |||||||||
| None | 8 | 8 | 1.00 | (referent) | None | 49 | 70 | 1.00 | (referent) |
| ≤30 | 27 | 23 | 0.85 | (0.27; 2.62) | ≤18.9 | 34 | 32 | 1.52 | (0.83; 2.78) |
| >30 | 35 | 17 | 0.48 | (0.15; 1.51) | >18.9 | 41 | 31 | 1.95 | (1.07; 3.54) |
| CCND2 | |||||||||
| None | 41 | 36 | 1.00 | (referent) | |||||
| ≤18.9 | 22 | 22 | 0.87 | (0.41; 1.85) | |||||
| >18.9 | 22 | 28 | 0.71 | (0.34; 1.46) | |||||
| BRCA1 | |||||||||
| None | 14 | 5 | 1.00 | (referent) | None | 76 | 79 | 1.00 | (referent) |
| ≤30 | 32 | 34 | 0.33 | (0.11; 1.03) | ≤18.9 | 52 | 36 | 1.54 | (0.91; 2.63) |
| >30 | 30 | 39 | 0.27 | (0.09; 0.83) | >18.9 | 49 | 45 | 1.15 | (0.68; 1.92) |
| FHIT | |||||||||
| None | 41 | 36 | 1.00 | (referent) | |||||
| ≤18.9 | 26 | 17 | 1.45 | (0.67; 3.12) | |||||
| >18.9 | 21 | 22 | 0.89 | (0.42; 1.91) | |||||
| SYK | |||||||||
| None | 14 | 5 | 1.00 | (referent) | None | 79 | 86 | 1.00 | (referent) |
| ≤30 | 34 | 38 | 0.29 | (0.09; 0.92) | ≤18.9 | 41 | 52 | 0.89 | (0.53; 1.49) |
| >30 | 31 | 42 | 0.23 | (0.07; 0.73) | >18.9 | 43 | 52 | 0.90 | (0.54; 1.50) |
a
Odds ratios (OR) for methylation above the median value and 95% confidence intervals (CI) were estimated with unconditional logistic regression model adjusted for age in years and estrogen receptor status. Abbreviations: SHS, secondhand smoke; M, median; OR, odds ratio; SFN, stratifin; SCGB3A1, secretoglobin, family 3A, member 1; RARB, retinoic acid receptor, beta; GSTP1, glutathione S-transferase pi 1; CDKN2A, cyclin-dependent kinase inhibitor 2A; CCND2, cyclin D2; BRCA1, breast cancer gene 1; FHIT, fragile histidine triad; SYK, spleen tyrosine kinase