Table 4.
Percent breast density according to estrogen and progesterone levels (N = 257), Madison, Wisconsin, 2008–2009
| Linear regression of square root percent breast density on progesterone levels | Mean percent densitya,b by progesterone quartile | ||||||
|---|---|---|---|---|---|---|---|
| β coefficientb | SE (β) | P | <33.0 pg/mL | 33.0–44.6 pg/mL | 44.7–59.1 pg/mL | ≥59.2 pg/mL | |
| Estradiol quartile | |||||||
| <6.0 pg/mL | 0.0055 | 0.0102 | 0.59 | 13.7 (11.7, 15.8) | 12.2 (10.2, 14.2) | 14.1 (11.8, 16.6) | 19.9 (16.3, 23.8) |
| 6.0–8.7 pg/mL | 0.0109 | 0.0073 | 0.14 | 11.7 (9.6, 14.0) | 13.8 (11.6, 16.1) | 14.3 (11.8, 17.2) | 15.5 (12.8, 18.5) |
| 8.8–12.3 pg/mL | 0.0083 | 0.0069 | 0.23 | 9.8 (7.8, 12.0) | 13.5 (10.2, 17.1) | 15.0 (13.0, 17.2) | 16.4 (14.0, 19.0) |
| ≥12.4 pg/mL | 0.0118 | 0.0054 | 0.03 | 10.6 (8.2, 13.4) | 9.2 (7.3, 11.4) | 12.0 (9.2, 15.3) | 12.6 (10.4, 14.9) |
| Pinteraction = 0.84 | |||||||
| Free estradiol quartile | |||||||
| <0.14 pg/mL | 0.0083 | 0.0080 | 0.30 | 14.5 (12.2, 16.9) | 14.5 (12.0, 17.1) | 15.3 (12.9, 17.8) | 20.2 (16.8, 23.8) |
| 0.14–0.22 pg/mL | 0.0102 | 0.0101 | 0.31 | 10.4 (8.6, 12.4) | 11.3 (9.4, 13.4) | 13.3 (10.8, 16.0) | 14.7 (12.0, 17.6) |
| 0.23–0.33 pg/mL | 0.0057 | 0.0083 | 0.49 | 11.0 (8.8, 13.4) | 12.9 (10.5, 15.6) | 14.2 (12.0, 16.5) | 15.6 (13.1, 18.2) |
| ≥0.33 pg/mL | 0.0104 | 0.0054 | 0.05 | 10.6 (8.3, 13.3) | 9.9 (7.9, 12.2) | 13.7 (11.0, 16.7) | 13.3 (11.1, 15.8) |
| Pinteraction = 0.85 | |||||||
aPercent density displayed is reverse transformed from model of square root density
bAdjusted for age (continuous), body mass index (continuous), parity (0, 1,2, 3+), vigorous physical activity (0–1.0, 1.1–4.0, >4.0 h/week), pack years of smoking (None, 1–15, >15), and family history of breast cancer (No, Yes)