TABLE 2.
Selected reproductive characteristics of women with breast cancer, women with proliferative and nonproliferative extratumoral tissue, women with proliferative and nonproliferative fibrocystic changes alone, and control subjects in Shanghai, China1
| Breast cancer cases |
Fibrocystic changes |
||||||
| Characteristic | All cases2 (n = 241) | Proliferative2 (n = 114) | Nonproliferative2 (n = 127) | All fibrocystic disease2 (n = 340) | Proliferative2 (n = 185) | Nonproliferative2 (n = 155) | Control subjects (n = 1030) |
| n (%) | n (%) | n (%) | |||||
| Age at menarche | |||||||
| ≤13 y | 42 (18.5) | 15 (12.2) | 27 (24.5)3 | 61 (14.4) | 29 (14.5) | 32 (15.1) | 167 (16.2) |
| 14 y | 42 (19.5) | 25 (24.4) | 17 (13.3)3 | 84 (24.1) | 52 (25.2) | 32 (22.8) | 199 (19.3) |
| 15 y | 58 (24.0) | 23 (21.4) | 35 (27.0)3 | 69 (20.4) | 36 (18.3) | 33 (20.8) | 201 (19.5) |
| 16 y | 46 (17.9) | 21 (14.9) | 25 (20.5)3 | 61 (16.8) | 30 (17.7) | 31 (16.1) | 214 (20.8) |
| ≥17 y | 53 (20.3) | 30 (27.8) | 23 (13.8)3 | 65 (24.5) | 38 (24.5) | 27 (25.5) | 248 (24.1) |
| Missing | 1 (0.10) | ||||||
| Number of live births | |||||||
| None | 13 (4.8)3 | 7 (5.9)3 | 6 (4.2) | 15 (4.0) | 9 (4.0)3 | 6 (3.5) | 37 (3.6) |
| 1 | 135 (65.8)3 | 73 (70.9)3 | 62 (61.7) | 269 (67.3) | 149 (68.6)3 | 120 (65.5) | 696 (67.6) |
| 2 | 41 (13.8)3 | 9 (6.6)3 | 32 (19.4) | 26 (11.4) | 13 (13.3)3 | 13 (8.6) | 118 (11.5) |
| ≥3 | 52 (15.9)3 | 25 (16.8)3 | 27 (15.0) | 28 (17.1)) | 14 (14.3)3 | 14 (21.6) | 175 (17.0) |
| Missing | 0 (0.0) | 0 (0.0) | 0 (0.0) | 2 (0.4) | 0 (0.0) | 2 (1.0) | 4 (0.4) |
| Age at first live birth | |||||||
| No live births | 15 (5.4) | 7 (5.9) | 8 (5.3) | 17 (4.4) | 9 (4.0) | 8 (4.5) | 41 (3.6) |
| ≤24 y | 63 (20.2) | 28 (20.2) | 35 (19.7) | 56 (27.3) | 29 (24.2) | 27 (12.5) | 260 (25.2) |
| 25–29 y | 116 (53.6) | 53 (50.1) | 63 (56.8) | 212 (57.9) | 115 (58.1) | 97 (57.5) | 582 (56.5) |
| ≥30 y | 47 (21.1) | 26 (24.1) | 21 (18.5) | 55 (13.6) | 32 (14.0) | 23 (12.8) | 147 (14.3) |
| Duration of breastfeeding | |||||||
| Never breastfed | 51 (22.8)3 | 24 (22.65) | 27 (24.1) | 90 (23.7) | 52 (23.4)3 | 38 (22.2) | 221 (21.5) |
| ≤6 mo | 46 (20.2)3 | 23 (20.3) | 23 (20.4 | 93 (25.1) | 53 (26.0)3 | 40 (25.5) | 205 (19.9) |
| 7–12 mo | 68 (32.3)3 | 39 (38.2) | 29 (25.9) | 106 (26.3) | 52 (25.8)3 | 54 (26.0) | 354 (34.4) |
| 13–24 mo | 34 (12.2)3 | 5 (3.6) | 29 (19.2) | 26 (10.9) | 13 (11.0)3 | 13 (11.7) | 109 (10.6) |
| ≥25 mo | 42 (12.8)3 | 23 (15.5) | 19 (10.6) | 25 (14.3) | 15 (14.1)3 | 10 (14.9) | 141 (13.7) |
| Duration of oral contraceptive use | |||||||
| Never used | 213 (89.1) | 101 (89.2) | 112 (88.6) | 301 (86.4) | 168 (89.2) | 133 (84.5) | 941 (91.4) |
| ≤1 y | 15 (6.6) | 7 (6.4) | 8 (6.6) | 19 (6.3) | 9 (4.4) | 10 (8.3) | 33 (3.2) |
| >1 y | 13 (4.5) | 6 (4.6) | 7 (5.0) | 20 (7.5) | 8 (6.6) | 12 (14.3) | 55 (5.3) |
| Missing | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (0.1) |
| Number of induced abortions | |||||||
| 0 | 100 (39.9) | 46 (40.6) | 54 (39.7) | 118 (31.9) | 70 (35.7) | 48 (28.6) | 416 (40.4) |
| 1 | 94 (39.5) | 46 (38.2) | 48 (39.8) | 148 (46.6) | 80 (46.7) | 68 (48.1) | 417 (40.5) |
| 2 | 34 (16.1) | 15 (15.5) | 19 (16.5) | 61 (18.1) | 29 (16.5) | 32 (19.8) | 162 (15.7) |
| Missing | 13 (4.8) | 7 (5.9) | 6 (4.2) | 13 (3.5) | 6 (3.0) | 7 (3.7) | 35 (3.4) |
| Number of breast lumps evaluated by medical worker | |||||||
| 0 | 312 (93.0)34 | 105 (92.6) | 120 (93.7) | 299 (89.1) | 158 (86.4)3 | 141 (92.9) | 999 (97.0) |
| 1 | 13 (4.8)34 | 8 (6.9) | 3 (3.0) | 26 (7.2) | 17 (9.1)3 | 9 (4.5) | 21 (2.0) |
| ≥2 | 5 (2.3)34 | 1 (0.7) | 4 (3.5) | 15 (3.9) | 10 (4.8)3 | 5 (2.8) | 10 (1.0) |
| Menopause | |||||||
| No | 131 (64.7) | 69 (67.8) | 62 (61.8)5 | 275 (66.8) | 147 (65.6) | 128 (68.8) | 669 (65.0) |
| Yes | 110 (35.5) | 45 (32.4) | 65 (38.3)5 | 65 (33.4) | 38 (34.6) | 27 (31.4) | 361 (35.1) |
1
P values for age-adjusted model were stratified by year of interview (1995–1996, 1997, 1998–1999, and 2000–2001) by conditional logistic regression.
2
Indirect age-adjusted percentages based on age distribution of controls.
3
Significantly different from control subjects, P < 0.05.
4
Significantly different from subjects with proliferative fibrocystic changes, P < 0.05.
5
Significantly different from subjects with nonproliferative fibrocystic changes, P < 0.05.