Characteristics of the study population (one random observation per woman, n = 222,019) according to family history. Frequency and column percentage
| Characteristic | No family history n = 144,930 (65%) | Second degree only n = 40,253 (18%) | First degree only n = 24,028 (11%) | First and second degree n = 11,376 (5.1%) | Male relativean = 1,432 (0.6%) |
|---|---|---|---|---|---|
| Age group, y, n (%) | |||||
| 35–39 | 7,100 (4.9) | 3,270 (8.1) | 1,313 (5.5) | 931 (8.2) | 79 (5.5) |
| 40–44 | 22,043 (15) | 8,118 (20) | 2,835 (12) | 1,670 (15) | 193 (14) |
| 45–49 | 24,738 (17) | 7,654 (19) | 3,536 (15) | 1,878 (17) | 265 (19) |
| 50–54 | 26,259 (18) | 7,060 (18) | 3,933 (16) | 2,006 (18) | 233 (16) |
| 55–59 | 22,714 (16) | 5,478 (14) | 3,970 (17) | 1,788 (16) | 241 (17) |
| 60–64 | 18,603 (13) | 4,212 (11) | 3,572 (15) | 1,444 (13) | 173 (12) |
| 65–69 | 13,022 (9.0) | 2,769 (6.9) | 2,645 (11) | 973 (8.6) | 147 (10) |
| 70–74 | 10,451 (7.2) | 1,692 (4.2) | 2,224 (9.3) | 686 (6.0) | 101 (7.1) |
| BMI, n (%) | |||||
| BMI < 18.5 | 2,528 (1.9) | 559 (1.5) | 415 (1.8) | 162 (1.5) | 24 (1.9) |
| 18.5 ≤ BMI < 24.9 | 54,876 (41) | 14,968 (39) | 9,032 (40) | 4,162 (38) | 471 (36) |
| 25.0 ≤ BMI < 29.9 | 40,591 (30) | 11,154 (29) | 6,813 (30) | 3,265 (30) | 404 (31) |
| 30.0 ≤ BMI < 34.9 | 20,240 (15) | 6,175 (16) | 3,437 (15) | 1,740 (16) | 216 (17) |
| BMI ≥ 35.0 | 16,591 (12) | 5,569 (15) | 2,753 (12) | 1,586 (15) | 179 (14) |
| [Missing] | 10,104 | 1,828 | 1,578 | 461 | 138 |
| BI-RADS breast density, n (%) | |||||
| Almost entirely fat | 14,147 (9.8) | 3,339 (8.3) | 2,193 (9.1) | 908 (8.0) | 149 (10) |
| Scattered fibroglandular densities | 52,532 (36) | 13,960 (35) | 8,766 (37) | 3,987 (35) | 511 (36) |
| Heterogeneously dense | 60,666 (42) | 17,724 (44) | 10,157 (42) | 5,008 (44) | 616 (43) |
| Extremely dense | 17,585 (12) | 5,230 (13) | 2,912 (12) | 1,473 (13) | 156 (11) |
| Age at first birth, n (%) | |||||
| Nulliparous | 34,640 (25) | 10,240 (26) | 5,965 (26) | 2,848 (26) | 358 (26) |
| Age < 30 | 77,148 (55) | 20,363 (52) | 12,772 (55) | 6,029 (54) | 762 (55) |
| Age ≥ 30 | 29,552 (21) | 8,702 (22) | 4,682 (20) | 2,278 (20) | 264 (19) |
| [Missing] | 3,590 | 948 | 609 | 221 | 48 |
| Age at menopause, years, n (%) | |||||
| Premenopausal | 44,836 (36) | 15,616 (44) | 6,575 (32) | 3,660 (36) | 390 (32) |
| <40 | 10,407 (8.2) | 3,328 (9.3) | 1,831 (8.8) | 1,158 (12) | 138 (11) |
| 40–49 | 30,846 (24) | 7,376 (21) | 5,026 (24) | 2,311 (23) | 323 (26) |
| 50–54 | 32,125 (25) | 7,407 (21) | 5,775 (28) | 2,361 (23) | 305 (25) |
| ≥55 | 8,257 (6.5) | 1,950 (5.5) | 1,598 (7.7) | 598 (5.9) | 71 (5.8) |
| [Missing] | 18,459 | 4,576 | 3,223 | 1,288 | 205 |
| Postmenopausal hormones, n (%) | |||||
| Yes | 21,590 (15) | 6,187 (16) | 3,304 (14) | 1,632 (15) | 168 (12) |
| No | 117,952 (85) | 32,778 (84) | 19,789 (86) | 9,388 (85) | 1,193 (88) |
| [Missing] | 5,388 | 1,288 | 935 | 356 | 71 |
| Race/ethnicity, n (%) | |||||
| White, non-Hispanic | 94,056 (65) | 32,844 (82) | 17,893 (75) | 9,479 (84) | 912 (64) |
| Black, non-Hispanic | 6,009 (4.2) | 1,341 (3.3) | 990 (4.1) | 381 (3.4) | 89 (6.3) |
| Asian | 29,129 (20) | 2,591 (6.5) | 3,025 (13) | 580 (5.1) | 223 (16) |
| American Indian/Alaska Native | 567 (0.4) | 153 (0.4) | 110 (0.5) | 45 (0.4) | 8 (0.6) |
| Hispanic | 9,662 (6.7) | 1,781 (4.4) | 1,173 (4.9) | 444 (3.9) | 135 (9.5) |
| Other | 4,411 (3.1) | 1,328 (3.3) | 684 (2.9) | 398 (3.5) | 57 (4.0) |
| [Missing] | 1,096 | 215 | 153 | 49 | 8 |
| Ovarian cancer in family, n (%) | |||||
| Yes | 6,026 (5.4) | 2,393 (8.1) | 1,608 (8.9) | 999 (12) | 174 (15) |
| No | 106,024 (95) | 27,239 (92) | 16,411 (91) | 7,696 (89) | 980 (85) |
| [Missing] | 32,880 | 10,621 | 6,009 | 2,681 | 278 |
NOTE: Proportions may not add to 100% due to rounding.
↵aWomen with a male relative affected by breast cancer were placed in the male relative category regardless of breast cancer among female relatives.