Table 3.
Five-Year Cancer Risk Estimates After a Screening Mammography Examination by Breast Density, Age, Menopausal Status, and HT Use Assuming BMI = 25 kg/m2
| Age | BIRADS Breast Density* | |||||||
|---|---|---|---|---|---|---|---|---|
| 1 |
2 |
3 |
4 |
|||||
| 5 Year Risk %† | 95% CI | 5-Year Risk %† | 95% CI | 5-Year Risk %† | 95% CI | 5-Year Risk %† | 95% CI | |
| Premenopausal‡ | ||||||||
| 30-34 | 0.3 | 0.0 to 0.9 | 0.5 | 0.2 to 0.7 | 0.9 | 0.6 to 1.3 | 0.7 | 0.2 to 1.1 |
| 35-39 | 0.1 | 0.0 to 0.3 | 0.7 | 0.6 to 0.9 | 1.1 | 0.9 to 1.2 | 1.5 | 1.2 to 1.7 |
| 40-44 | 0.4 | 0.2 to 0.5 | 0.9 | 0.8 to 0.9 | 1.5 | 1.4 to 1.6 | 1.8 | 1.7 to 2.0 |
| 45-49 | 0.7 | 0.5 to 0.9 | 1.3 | 1.2 to 1.4 | 2.1 | 1.9 to 2.2 | 2.5 | 2.3 to 2.7 |
| 50-54 | 0.8 | 0.4 to 1.1 | 1.5 | 1.4 to 1.7 | 2.3 | 2.1 to 2.5 | 3.1 | 2.7 to 3.5 |
| Postmenopausal and no HT use‡ | ||||||||
| 30-45 | 0.2 | 0.1 to 0.5 | 0.7 | 0.5 to 1.0 | 1.1 | 0.7 to 1.4 | 1.2 | 0.5 to 1.9 |
| 45-49 | 0.5 | 0.2 to 0.7 | 0.8 | 0.7 to 1.0 | 1.6 | 1.3 to 1.8 | 2.2 | 1.6 to 2.7 |
| 50-54 | 0.6 | 0.5 to 0.8 | 1.3 | 1.2 to 1.4 | 1.8 | 1.6 to 1.9 | 2.2 | 1.8 to 2.6 |
| 55-59 | 0.8 | 0.6 to 0.9 | 1.7 | 1.6 to 1.8 | 2.4 | 2.3 to 2.6 | 2.4 | 2.0 to 2.8 |
| 60-64 | 1.1 | 1.0 to 1.3 | 2.0 | 1.9 to 2.1 | 2.7 | 2.5 to 2.9 | 2.8 | 2.2 to 3.4 |
| 65-69 | 1.2 | 1.1 to 1.4 | 2.3 | 2.2 to 2.5 | 3.2 | 3.0 to 3.4 | 3.4 | 2.7 to 4.2 |
| 70-79 | 1.7 | 1.5 to 1.9 | 2.6 | 2.5 to 2.7 | 3.4 | 3.0 to 3.6 | 3.4 | 2.8 to 4.1 |
| 80+ | 1.5 | 1.2 to 1.7 | 2.6 | 2.4 to 2.8 | 2.6 | 2.3 to 2.9 | 3.5 | 2.4 to 4.5 |
| Postmenopausal and HT use‡ | ||||||||
| 30-45 | 0.3 | 0.1 to 0.5 | 0.6 | 0.4 to 0.7 | 1.1 | 0.8 to 1.3 | 1.1 | 0.7 to 1.6 |
| 45-49 | 0.5 | 0.3 to 0.8 | 0.9 | 0.8 to 1.1 | 1.5 | 1.3 to 1.7 | 2.2 | 1.8 to 2.7 |
| 50-54 | 0.6 | 0.4 to 0.8 | 1.3 | 1.2 to 1.4 | 2.3 | 2.1 to 2.4 | 2.8 | 2.5 to 3.2 |
| 55-59 | 0.8 | 0.6 to 1.0 | 1.8 | 1.7 to 2.0 | 3.1 | 2.9 to 3.3 | 4.3 | 3.8 to 4.8 |
| 60-64 | 1.0 | 0.7 to 1.2 | 2.0 | 1.9 to 2.2 | 3.4 | 3.2 to 3.7 | 4.1 | 3.5 to 4.8 |
| 65-69 | 1.6 | 1.2 to 2.0 | 2.3 | 2.1 to 2.5 | 3.6 | 3.3 to 3.9 | 3.6 | 2.8 to 4.4 |
| 70-79 | 1.5 | 1.2 to 1.9 | 2.9 | 2.6 to 3.1 | 3.3 | 3.1 to 3.6 | 4.2 | 3.5 to 5.0 |
| 80+ | 1.3 | 0.5 to 2.2 | 2.5 | 2.0 to 3.0 | 4.3 | 3.6 to 5.0 | 4.4 | 2.5 to 6.2 |
Abbreviations: HT, hormone therapy; BMI, body mass index; BIRADS, Breast Imaging Reporting and Data System.
BIRADS density 1 = almost entirely fat (low breast density); 2 = scattered fibroglandular densities (average breast density); 3 = heterogeneously dense (high breast density); 4 = extremely dense (very high breast density).
Risk estimates come from the partly conditional Cox proportional hazards models assuming interactions between HT use, menopausal status, and breast density using robust sandwich variance estimates to account for multiple mammography estimations per woman adjusting for age category, BMI, BMI2, interactions between BMI and BMI2 with menopausal status (since they were significant P = .002 and P = .017, respectively), E, E + P, and registry. Interaction terms use a hierarchical algorithm in which all lower order main effects or interactions are included in the model regardless of statistical significance. Risk estimates were calculated for women with a BMI = 25 kg/m2 (approximate average BMI in population) and average registry (proportions of mammography examinations from each registry).
Premenopausal group with n = 3,856 breast cancers; postmenopausal no HT group with n = 5,700 breast cancers; postmenopausal HT group with n = 4,534 breast cancers.