Table 5.
Survival model results for the relation between mammographic density and risk of breast cancer death, stratified by BMI*
| BMI, kg/m2 | BI-RADS breast density | No. of breast cancer deaths | HR (95% CI)† | P‡ |
|---|---|---|---|---|
| 18.5 – <25 | Almost entirely fat | 16 | 1.27 (0.74 to 2.17) | .24 |
| Scattered | 107 | 1 (referent) | ||
| Heterogeneous | 166 | 1.05 (0.80 to 1.38) | ||
| Extremely dense | 43 | 0.75 (0.50 to 1.12) | ||
| 25 – <30 | Almost entirely fat | 16 | 0.70 (0.40 to 1.23) | .24 |
| Scattered | 104 | 1 (referent) | ||
| Heterogeneous | 122 | 1.04 (0.79 to 1.37) | ||
| Extremely dense | 28 | 1.39 (0.89 to 2.17) | ||
| ≥30 | Almost entirely fat | 40 | 2.02 (1.37 to 2.97) | .003 |
| Scattered | 135 | 1 (referent) | ||
| Heterogeneous | 99 | 1.05 (0.79 to 1.38) | ||
| Extremely dense | 13 | 0.87 (0.48 to 1.58) |
* BI-RADS, Breast Imaging Reporting and Data System; BMI, body mass index; CI, confidence interval; HR, hazard ratio. N = 96 women excluded from cause-specific models. All tumors: BMI × density interaction, P = .007.
† Fully adjusted model includes covariates for American Joint Committee on Cancer stage (I, IIA, IIB, III, IV), registry (five sites), age at diagnosis (30–44, 45–49, 50–54, 55–59, 60–64, 65–69, 70–74, 75–79, ≥80 years), year of diagnosis (1996–1998, 1999–2001, 2002–2003, 2004–2005), mode of detection (screen-detected, interval-detected, other screen, clinically detected, other), surgery/radiation (no breast surgery, breast conserving therapy without radiation, breast conserving therapy with radiation, other surgery), chemotherapy (yes/no), and annual median income (<$42 000, $42 000 – <$52 000, $52 000 – <$66 000, ≥$66 000). Women with missing covariate information were excluded.
‡ P value from Wald statistic to test for an overall effect of categorical BI-RADS density. All statistical tests were two-sided.