Table 2.
Association of alcohol and tobacco use with mammographic density phenotypes.
| Percent Density (%) | Dense Area (cm2) | Nondense Area (cm2) | ||||||
|---|---|---|---|---|---|---|---|---|
| N | % | β (95% CI) | p | β (95% CI) | p | β (95% CI) | p | |
| Alcohol use | ||||||||
| None | 9413 | 40.1 | Referent | |||||
| 1–4 DPW | 7238 | 30.9 | 0.08 (−0.58, 0.74) | 0.8073 | −0.30 (−1.29, 0.69) | 0.5542 | −1.94 (−3.41, −0.47) | 0.0098 |
| 5+ DPW | 6805 | 29.0 | 0.45 (0.07, 0.83) | 0.0195 | 0.28 (−0.41, 0.96) | 0.4250 | −3.71 (−7.06, −0.35) | 0.0314 |
| p for trend | 0.0149 | 0.2323 | 0.0189 | |||||
| Tobacco use | ||||||||
| Never | 14233 | 60.7 | Referent | |||||
| <1/2 PPD | 2943 | 12.6 | −0.02 (−0.48, 0.45) | 0.9436 | 0.69 (0.03, 1.34) | 0.0383 | 1.77 (−0.14, 3.69) | 0.0693 |
| 1/2–1 PPD | 3587 | 15.3 | −0.47 (−0.89, −0.04) | 0.0322 | 0.08 (−0.52, 0.68) | 0.7984 | 2.83 (0.64, 5.03) | 0.0110 |
| 1+ PPD | 2693 | 11.5 | −0.76 (−1.23, −0.28) | 0.0021 | −0.20 (−0.88, 0.49) | 0.5731 | 4.37 (2.33, 6.40) | <0.0001 |
| p for trend | 0.0008 | 0.9340 | <0.0001 | |||||
All models were adjusted for age, age2, BMI, BMI2, BMI3, late adolescent BMI, age at menarche, age at first birth, parity, menopausal status, menopausal hormone therapy (MHT) use, first-degree relative with breast cancer, physical activity, and image batch. Effects were estimated using separate linear regression models of the square-root transformed phenotype in the Hologic and GE cohorts, and combined using restricted maximum likelihood (REML) random effects meta-analysis. Coefficients (β) and 95% confidence intervals (CI) were back-transformed to the original scale. DPW = drinks per week; PPD = packs per day; BMI = body mass index.