Table 2.
Odds Ratios and PARP of Breast Cancer Risk Factors in Women Undergoing Screening or Diagnostic Mammographya
| Characteristic | Women With Breast Cancer | |||
|---|---|---|---|---|
| Premenopausal (n = 58 146) |
Postmenopausal (n = 144 600) |
|||
| OR (95% CI)b | PARP, % (95% CI)c | OR (95% CI)b | PARP, % (95% CI)c | |
| Family history of breast cancer | ||||
| No | 1 [Reference] | 8.7 (7.3–10.1) | 1 [Reference] | 8.2 (7.2–9.1) |
| Yes | 1.71 (1.59–1.84) | 1.53 (1.46–1.60) | ||
| BMId | ||||
| Underweight | 0.93 (0.76–1.15) | NA | 0.79 (0.67–0.93) | 22.8 (18.3–27.3)e |
| Normal | 1 [Reference] | 1 [Reference] | ||
| Overweight | 0.99 (0.93–1.07) | 1.23 (1.17–1.28) | ||
| Obesity class I | 1.00 (0.91–1.10) | 1.39 (1.31–1.47) | ||
| Obesity class II or III | 1.05 (0.94–1.18) | 1.54 (1.45–1.64) | ||
| History of benign breast biopsy | ||||
| No | 1 [Reference] | 6.9 (5.5–8.4) | 1 [Reference] | 8.6 (8.0–9.2) |
| Yes | 1.50 (1.40–1.62) | 1.41 (1.35–1.47) | ||
| Age at first live birth | ||||
| Nulliparous | 1.14 (1.05–1.22) | 8.7 (4.8–12.7) | 1.20 (1.14–1.26) | 5.2 (4.2–6.2) |
| ≤30 y | 1 [Reference] | 1 [Reference] | ||
| >30 y | 1.28 (1.19–1.37) | 1.23 (1.16–1.30) | ||
| BI-RADS breast densityf | ||||
| Almost entirely fat | 0.47 (0.38–0.58) | 39.3 (36.6–42.0)g | 0.62 (0.58–0.67) | 26.2 (24.4–28.0)g |
| Scattered fibroglandular densities | 1 [Reference] | 1 [Reference] | ||
| Heterogeneously dense | 1.57 (1.46–1.69) | 1.40 (1.34–1.45) | ||
| Extremely dense | 1.81 (1.65–1.99) | 1.58 (1.46–1.71) | ||
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); NA, not applicable; OR, odds ratio; PARP, population-attributable risk proportion.
Estimated by multivariable conditional logistic regression.
Odds ratios presented were adjusted for family history of breast cancer, BMI, history of benign breast biopsy, age at first live birth, and Breast Imaging Reporting and Data System (BI-RADS) breast density.
PARP calculated using multivariable adjusted ORs.
Underweight, BMI less than 18.5; normal, 18.5–24.9; overweight, 25.0–29.9; obesity class I, 30.0–34.9; and obesity class II or III, 35.0 or more.
PARP calculated for shifting everyone to normal weight and holding underweight constant.
BI-RADS classification system: a, almost entirely fat; b, scattered fibroglandular densities; c, heterogeneously dense; and d, extremely dense.22
PARP calculated for shifting the BI-RADS categories heterogeneously dense and extremely dense to scattered fibroglandular densities, and holding almost entirely fat constant.