Table 1.
Distribution of sociodemographic and smoking characteristics in breast cancer cases and controls, multi-case-control study (MCC-Spain), 2008–2013, Spain (N=3636)
| Characteristics | Total | Pre-menopausal | Post-menopausal | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Cases n (%) | Controls n (%) | p | Cases n (%) | Controls n (%) | p | Cases n (%) | Controls n (%) | p | |
| (N=1733) | (N=1903) | (N=610) | (N=547) | (N=1122) | (N=1352) | ||||
| Sociodemographic | |||||||||
| Age (years), mean (SD) | 56.4 (12.6) | 59.1 (13.2) | <0.001 | 44.0 (6.4) | 43.5 (6.1) | 0.154 | 63.1 (9.7) | 65.4 (9.6) | <0.001 |
| Education level | |||||||||
| No education/primary studies | 831 (48.0) | 912 (47.9) | 149 (24.4) | 109 (19.9) | 682 (60.8) | 801 (59.2) | |||
| Secondary school | 573 (33.1) | 588 (30.9) | 282 (46.2) | 228 (41.7) | 290 (25.8) | 359 (26.6) | |||
| University graduate | 329 (19.0) | 403 (21.2) | 0.174 | 179 (29.3) | 210 (38.4) | 0.004 | 150 (13.4) | 192 (14.2) | 0.717 |
| Body mass index (kg/m²) | |||||||||
| <18.5 | 28 (1.8) | 37 (2.3) | 18 (3.2) | 21 (4.3) | 10 (1.0) | 16 (1.4) | |||
| 18.5–25.0 | 741 (46.3) | 809 (49.3) | 368 (65.8) | 299 (60.9) | 372 (35.8) | 510 (44.3) | |||
| 25.0–30.0 | 541 (33.8) | 509 (31.0) | 135 (24.2) | 113 (23.0) | 406 (39.0) | 396 (34.4) | |||
| ≥30.0 | 290 (18.1) | 287 (17.5) | 0.197 | 38 (6.8) | 58 (11.8) | 0.028 | 252 (24.2) | 229 (19.9) | <0.001 |
| Alcohol intake (g/day) | |||||||||
| Non-drinker | 530 (34.1) | 649 (30.6) | 171 (28.0) | 156 (28.5) | 359 (32.0) | 491 (36.3) | |||
| <7 | 544 (30.1) | 572 (31.4) | 242 (39.7) | 203 (37.1) | 302 (26.9) | 369 (27.3) | |||
| ≥7 | 439 (24.1) | 458 (25.3) | 130 (21.3) | 125 (22.9) | 308 (27.5) | 333 (24.6) | |||
| Amount unknown | 224 (11.8) | 220 (12.7) | 0.106 | 67 (11.0) | 63 (11.5) | 0.665 | 153 (13.6) | 159 (11.8) | 0.082 |
| Age at menarche, mean (SD) | 12.8 (1.6) | 12.9 (1.6) | 0.120 | 12.6 (1.4) | 12.7 (1.5) | 0.602 | 12.8 (1.6) | 12.9 (1.7) | 0.211 |
| Age at first birth, mean (SD) | 26.7 (5.0) | 26.5 (4.8) | 0.270 | 28.0 (5.6) | 28.0 (5.6) | 0.986 | 26.1 (4.5) | 26.0 (4.3) | 0.743 |
| Number of children | |||||||||
| None | 351 (20.3) | 355 (18.7) | 155 (25.5) | 153 (28.2) | 196 (17.5) | 202 (15.0) | |||
| 1–2 | 993 (57.5) | 1042 (55.0) | 392 (64.4) | 340 (62.6) | 601 (53.8) | 700 (51.9) | |||
| 3–4 | 336 (19.5) | 406 (21.4) | 58 (9.5) | 44 (8.1) | 278 (24.9) | 361 (26.8) | |||
| >4 | 47 (2.7) | 92 (4.9) | 0.002 | 4 (0.7) | 6 (1.1) | 0.521 | 43 (3.8) | 86 (6.4) | 0.011 |
| Oral contraceptive use (years) | |||||||||
| Never | 914 (52.9) | 971 (51.1) | 211 (34.7) | 163 (29.9) | 703 (62.8) | 808 (59.9) | |||
| ≤5 | 370 (21.4) | 375 (19.7) | 162 (26.6) | 149 (27.3) | 208 (18.6) | 224 (16.6) | |||
| >5 | 216 (12.5) | 284 (15.0) | 119 (19.6) | 127 (23.3) | 97 (8.7) | 156 (11.6) | |||
| Duration unknown | 227 (13.1) | 269 (14.2) | 0.060 | 116 (19.1) | 107 (19.6) | 0.138 | 111 (9.9) | 162 (12.0) | 0.031 |
| Age at menopause, mean (SD) | - | - | - | - | - | - | 49.1 (5.3) | 48.4 (5.3) | 0.005 |
| Hormone replacement therapy (years) | |||||||||
| Never | - | - | - | - | - | - | 965 (89.3) | 1147 (89.4) | |
| ≤5 | - | - | - | - | - | - | 74 (6.8) | 89 (6.9) | |
| >5 | - | - | - | - | - | - | 31 (2.9) | 37 (2.9) | |
| Duration unknown | - | - | - | - | - | - | 11 (1.0) | 10 (0.8) | 0.997 |
| Previous biopsies | |||||||||
| None | 1571 (92.5) | 1797 (98.0) | 566 (94.8) | 534 (98.2) | 1005 (91.3) | 1263 (97.9) | |||
| Yes | 127 (7.5) | 37 (2.0) | <0.001 | 31 (5.2) | 10 (1.8) | 0.002 | 96 (8.7) | 27 (2.1) | <0.001 |
| Family history of breast cancer | |||||||||
| None | 1303 (75.2) | 1631 (85.7) | 432 (70.8) | 470 (85.9) | 870 (77.5) | 1157 (85.6) | |||
| Second degree only | 174 (10.0) | 106 (5.6) | 88 (14.4) | 48 (8.8) | 86 (7.7) | 58 (4.3) | |||
| 1 First degree | 224 (12.9) | 155 (8.1) | 81 (13.3) | 29 (5.3) | 143 (12.7) | 126 (9.3) | |||
| First degree | 32 (1.8) | 11 (0.6) | <0.001 | 9 (1.5) | 0 (0.0) | <0.001 | 23 (2.0) | 11 (0.8) | <0.001 |
| Smoking | |||||||||
| Smoking status 1 year before the interview | |||||||||
| Never smoker | 972 (56.4) | 1142 (60.1) | 242 (40.0) | 237 (43.5) | 730 (65.4) | 904 (66.9) | |||
| Former smoker ≥10 | 170 (9.9) | 180 (9.5) | 61 (10.1) | 53 (9.7) | 109 (9.8) | 126 (9.3) | |||
| Former smoker <10 | 168 (9.8) | 189 (9.9) | 83 (13.7) | 80 (14.7) | 85 (7.6) | 109 (8.1) | |||
| Active smoker | 413 (24.0) | 390 (20.5) | 0.068 | 219 (36.2) | 175 (32.1) | 0.483 | 193 (17.3) | 213 (15.8) | 0.715 |
| Duration of tobacco use (years) | |||||||||
| Never smoker | 972 (56.5) | 1142 (60.2) | 242 (40.1) | 237 (43.5) | 730 (65.5) | 904 (67.0) | |||
| <20 | 247 (14.4) | 229 (12.1) | 151 (25.0) | 130 (23.9) | 96 (8.6) | 98 (7.3) | |||
| 20–30 | 249 (14.5) | 228 (12.0) | 150 (24.8) | 138 (25.3) | 99 (8.9) | 89 (6.6) | |||
| >30 | 251 (14.6) | 299 (15.8) | 0.014 | 61 (10.1) | 40 (7.3) | 0.325 | 189 (17.0) | 258 (19.1) | 0.061 |
| Intensity (cigarettes/day) | |||||||||
| Never smoker | 972 (56.8) | 1142 (60.9) | 242 (40.2) | 237 (44.0) | 730 (65.8) | 904 (67.8) | |||
| <15 | 356 (20.8) | 363 (19.3) | 180 (29.9) | 153 (28.4) | 175 (15.8) | 209 (15.7) | |||
| ≥15 | 384 (22.4) | 371 (19.8) | 0.039 | 180 (29.9) | 149 (27.6) | 0.430 | 204 (18.4) | 220 (16.5) | 0.447 |
| Years smoking before first birth | |||||||||
| Never smoker | 801 (61.2) | 939 (64.7) | 177 (40.0) | 162 (42.5) | 624 (72.1) | 776 (72.7) | |||
| <10 | 255 (19.5) | 253 (17.4) | 118 (26.6) | 87 (22.8) | 137 (15.8) | 165 (15.4) | |||
| ≥10 | 253 (19.3) | 260 (17.9) | 0.161 | 148 (33.4) | 132 (34.6) | 0.447 | 105 (12.1) | 127 (11.9) | 0.957 |
| Cigarettes per day before first birth | |||||||||
| Never smoker | 801 (65.8) | 939 (68.2) | 177 (44.3) | 162 (47.0) | -801 | 776 (75.4) | |||
| <15 | 211 (17.3) | 226 (16.4) | 117 (29.3) | 95 (27.5) | 94 (11.5) | 130 (12.6) | |||
| ≥15 | 206 (16.9) | 212 (15.4) | 0.404 | 106 (26.5) | 88 (25.5) | 0.756 | 100 (12.2) | 123 (12.0) | 0.754 |
Chi-squared test or Student’s t-test were used to assess differences between cases and controls for each variable.