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Table. 1.

Table. 1.

Characteristics of case and controls by selected reproductive risk factors

Risk factor Total P-value BI-RADS 1 and 2 (< 50%) BI-RADS 3 (50%–75%) BI-RADS 4 (≥ 75%) P-value




Case Control Case Control Case Control Case Control
Age (yr) 46.86 ± 9.35 48.51 ± 9.93 < 0.0001 < 0.0001
 < 30 39 (1.8) 85 (4.0) < 0.0001 3 (1.4) 0 (0) 8 (0.8) 2 (0.2) 25 (4.0) 14 (3.3)
 30–39 436 (20.5) 213 (10.0) 27 (12.5) 3 (1.1) 175 (18.3) 33 (3.8) 175 (27.7) 55 (12.8)
 40–49 864 (40.7) 864 (40.7) 49 (22.7) 43 (15.9) 377 (39.4) 353 (41.0) 312 (49.4) 251 (58.4)
 50–59 572 (26.9) 640 (30.2) 74 (34.3) 97 (35.9) 308 (32.2) 348 (40.4) 106 (16.8) 91 (21.2)
 60–69 182 (8.6) 260 (12.3) 53 (24.5) 107 (39.6) 79 (8.3) 111 (12.9) 13 (2.1) 13 (3.0)
 ≥ 70 28 (1.3) 36 (1.7) 10 (4.6) 20 (7.4) 9 (0.9) 10 (1.2) 0 (0) 1 (0.2)
Age at menarche (yr) < 0.0001 0.0016
 < 15 1,520 (71.6) 1,212 (57.1) 118 (54.6) 99 (36.7) 658 (68.8) 442 (51.3) 502 (79.6) 276 (64.2)
 ≥ 15 574 (27.0) 706 (33.3) 93 (43.1) 136 (50.4) 281 (29.4) 322 (37.4) 123 (19.5) 120 (27.9)
 Unknown 29 (1.4) 184 (8.7) 5 (2.3) 35 (13.0) 17 (1.8) 97 (11.3) 6 (1.0) 34 (7.9)
Age at menopause (yr) 0.0518 < 0.0001
 Premenopausal 1,320 (62.2) 1,130 (53.9) 59 (27.3) 42 (15.6) 548 (57.3) 376 (43.9) 511 (81.0) 305 (71.8)
 < 50 390 (18.4) 475 (22.6) 65 (30.1) 93 (34.4) 199 (20.8) 233 (27.2) 69 (10.9) 65 (15.3)
 ≥ 50 411 (19.4) 493 (23.5) 92 (42.6) 135 (50.0) 209 (21.9) 248 (28.9) 51 (8.1) 55 (12.9)
Number of children 0.8015 < 0.0001
 0 358 (16.9) 285 (13.4) 10 (4.6) 10 (3.7) 146 (15.3) 61 (7.08) 143 (22.66) 72 (16.7)
 1 420 (19.8) 352 (16.6) 30 (13.9) 32 (11.9) 175 (18.3) 130 (15.10) 162 (25.67) 76 (17.7)
 ≥ 2 1,317 (62.0) 1,286 (60.6) 172 (79.6) 200 (74.1) 618 (64.6) 573 (66.55) 320 (50.71) 237 (55.1)
 Unknown 28 (1.3) 198 (9.3) 4 (1.9) 28 (10.4) 17 (1.8) 97 (11.27) 6 (0.95) 45 (10.5)
Age at first birth (yr) < 0.0001 < 0.0001
 < 28 822 (38.7) 871 (41.1) 133 (61.6) 144 (53.3) 394 (41.2) 387 (44.9) 164 (26.0) 153 (35.6)
 ≥ 28 910 (42.9) 734 (34.6) 69 (31.9) 79 (29.3) 398 (41.6) 298 (34.6) 315 (49.9) 155 (36.0)
 Nulliparous 358 (16.9) 285 (13.4) 10 (4.6) 10 (3.7) 146 (15.3) 61 (7.1) 143 (22.7) 72 (16.7)
 Unknown 33 (1.6) 231 (10.9) 4 (1.9) 37 (13.7) 18 (1.9) 115 (13.4) 9 (1.4) 50 (11.6)
Breast cancer in first-degree relatives 0.0100 0.0173
 0 1,597 (75.2) 1,633 (77.0) 163 (75.5) 212 (78.5) 719 (75.2) 667 (77.8) 473 (75.0) 345 (81.2)
 ≥ 1 317 (14.9) 228 (10.7) 37 (17.1) 24 (8.9) 143 (15.0) 80 (9.3) 85 (13.5) 29 (6.8)
 Unknown 209 (9.8) 240 (11.3) 16 (7.4) 34 (12.6) 94 (9.8) 110 (12.8) 73 (11.6) 51 (12.0)
Body mass index (kg/m2) 0.0001 0.4964
 < 25 1,572 (74.0) 1,581 (74.5) 114 (52.8) 159 (58.9) 664 (69.5) 620 (72.3) 560 (88.7) 369 (86.8)
 ≥ 25 484 (23.5) 355 (16.7) 91 (42.1) 81 (30.0) 259 (27.1) 153 (1.9) 57 (9.0) 28 (6.6)
 Unknown 65 (2.5) 162 (7.6) 11 (5.1) 30 (11.1) 33 (3.5) 84 (1.1) 14 (2.2) 28 (6.6)

Values are presented as Mean ± SD or number (%). BI-RADS, Breast Imaging-Reporting and Data System.

J Cancer Prev 2019;24:26-32 https://doi.org/10.15430/JCP.2019.24.1.26
© 2019 J Cancer Prev