Table 2. Distribution (row percentages) of breast density by age, and distribution (column percentages) of BCSC 5-year risk by breast density.
| BI-RADS BREAST DENSITY* | |||||
|---|---|---|---|---|---|
| Almost entirely fat | Scattered fibroglandular densities | Heterogeneously dense | Extremely dense | ||
| Age (years) | Row Percentages | Total | |||
| 40-49 | 6.5 | 32.0 | 47.7 | 13.9 | 243,964 |
| 50-59 | 11.7 | 40.9 | 39.8 | 7.6 | 298,278 |
| 60-69 | 15.7 | 47.5 | 32.8 | 4.0 | 221,580 |
| 70-74 | 16.9 | 50.9 | 29.7 | 2.6 | 67,633 |
| BCSC 5-year risk† | Column Percentages | ||||
| 0-<1.00% | 67.1 | 37.6 | 22.7 | 18.7 | |
| 1.00-1.66% | 23.0 | 30.0 | 28.3 | 33.8 | |
| 1.67-2.49% | 8.7 | 21.2 | 29.4 | 21.7 | |
| 2.50-3.99% | 1.2 | 9.7 | 13.9 | 16.4 | |
| ≥4.00% | 0 | 1.5 | 5.6 | 9.4 | |
| Total | 96,822 | 339,966 | 327,746 | 66,921 | 831,455 |
*
Breast Imaging Reporting and Data System (BI-RADS)
†
Breast Cancer Surveillance Consortium (BCSC) 5-year risk calculated using age, race, first degree family history of breast cancer, history of breast biopsy, BI-RADS density. Risk categories are defined as low (0-<1.00%), average (1.00-1.66%), intermediate (1.67%-2.49%), high (2.5%-3.99%) and very high (>3.99%).