Table 1.
Baseline characteristics of the benign breast disease (BBD) patients, overall and by breast cancer case-control status, Kaiser Permanente Northwest Center for Health Research, 1970-2015
| Overall, No. (%) | Controls, No. (%) | Cases, No. (%) | P a | |
|---|---|---|---|---|
| Characteristic | (n = 1028) | (n = 514) | (n = 514) | |
| Median age at BBD (range), y | 51.5 (18.7-86.6) | 51.4 (21.7-86.2) | 51.5 (18.7-86.6) | .97 |
| Median follow-up time (range), y | 9 (0.6-37.5) | 9 (0.6-37.3) | 9 (1.0-37.5) | 1.00 |
| Age at menarche, y | ||||
| ≤12 | 368 (45.5) | 185 (44.6) | 183 (46.4) | .62 |
| 13 | 245 (30.3) | 132 (31.8) | 113 (28.7) | |
| ≥ 14 | 198 (24.2) | 98 (23.6) | 98 (24.9) | |
| Parity and age at first live birth | ||||
| Nulliparous/AFLB ≥30 y | 225 (25.9) | 98 (22.1) | 127 (30.0) | .008 |
| Parous/AFLB <30 y | 643 (74.1) | 346 (77.9) | 297 (70.0) | |
| Body mass index, kg/m2 | ||||
| <25 | 425 (45.8) | 213 (45.8) | 212 (45.7) | .72 |
| 25-30 | 281 (30.2) | 136 (29.2) | 145 (31.2) | |
| >30 | 223 (24.0) | 116 (25.0) | 107 (23.1) | |
| Family history | ||||
| Absent | 791 (82.2) | 408 (84.6) | 383 (79.8) | .04 |
| Present | 171 (17.8) | 74 (15.4) | 97 (20.2) | |
| Menopause and MHT use | ||||
| Premenopausal | 412 (43.4) | 203 (41.9) | 209 (45.0) | .12 |
| Postmenopausal MHT use | 393 (41.4) | 211 (43.5) | 182 (39.2) | |
| Postmenopausal no MHT | 20 (2.1) | 14 (2.9) | 6 (1.3) | |
| Postmenopausal unknown MHT | 124 (13.1) | 57 (11.7) | 67 (14.5) | |
| Bilateral oophorectomy | ||||
| No | 805 (86.3) | 394 (83.8) | 411 (88.8) | .02 |
| Yes | 128 (13.7) | 76 (16.2) | 52 (11.2) | |
| BBD histology | ||||
| Nonproliferative | 708 (68.9) | 384 (74.7) | 324 (63.0) | <.001 |
| Proliferative, no atypia | 287 (27.9) | 124 (24.1) | 163 (31.7) | |
| Atypical hyperplasia | 33 (3.2) | 6 (1.2) | 27 (5.3) | |
| Sclerosing adenosis | ||||
| Absent | 942 (91.6) | 478 (93.0) | 464 (90.3) | .11 |
| Present | 86 (8.4) | 36 (7.0) | 50 (9.7) | |
| Radial scar present | ||||
| Absent | 977 (95.0) | 497 (96.7) | 480 (93.4) | .01 |
| Present | 51 (5.0) | 17 (3.3) | 34 (6.6) | |
| Fibroadenoma | ||||
| Absent | 878 (85.4) | 439 (85.4) | 439 (85.4) | .74 |
| Simple | 133 (12.9) | 68 (13.2) | 65 (12.6) | |
| Complex | 17 (1.7) | 7 (1.4) | 10 (2.0) | |
| Columnar cell hyperplasia | ||||
| Absent | 875 (85.5) | 450 (87.9) | 425 (83.0) | .03 |
| Present | 149 (14.5) | 62 (12.1) | 87 (17.0) | |
| Lobular involution | ||||
| Absent | 475 (52.5) | 235 (52.8) | 240 (52.2) | .09 |
| Partial | 176 (19.5) | 75 (16.9) | 101 (22.0) | |
| Complete | 254 (28.0) | 135 (30.3) | 119 (25.8) |
a
P values comparing cases and controls were obtained from χ2 tests (for categorical variables) and Kruskal-Wallis test (for continuous variables). AFLB = age at first live birth; MHT = menopausal hormone therapy use.