Table 1 Characteristics (mean (SD), or number (percentage)) of patients (cases) and controls, by mode of detection (screen-detected or interval breast cancer)
| Â | Interval cancer | Screen-detected cancer | ||||
|---|---|---|---|---|---|---|
Cases (n = 168) Mean (SD) | Controls (n = 498) Mean (SD) | P a | Cases (n = 422) Mean (SD) | Controls (n = 1197) Mean (SD) | P a | |
Age at mammogram (years) | 56.0 (6.8) | 56.2 (6.8) | 0.2 | 58.8 (7.5) | 58.4 (7.6) | 0.007 |
Body mass index (kg/m2) | 26.7 (5.3) | 26.5 (4.9) | 0.8 | 27.3 (5.0) | 26.5 (4.8) | 0.002 |
Number of live births | 2.6 (0.9) | 2.7 (0.9) | 0.2 | 2.8 (1.0) | 2.7 (0.9) | 0.96 |
| Â | N (%) | N (%) | P | N (%) | N (%) | P |
Parity | ||||||
 Yes | 139 (83) | 425 (85) | 0.4 | 359 (85) | 1046 (87) | 0.3 |
 No | 29 (17) | 73 (15) |  | 63 (15) | 151 (13) |  |
Menopausal status | ||||||
 Premenopausal | 67 (40) | 197 (40) | 0.6 | 127 (30) | 359 (30) | 0.3 |
 Postmenopausal | 101 (60) | 301 (60) |  | 295 (70) | 838 (70) |  |
Breast feeding | ||||||
 Yes | 123 (73) | 380 (76) | 0.5 | 327 (77) | 937 (78) | 0.7 |
 No | 41 (25) | 110 (22) |  | 88 (21) | 240 (20) |  |
 Missing | 4 (2) | 8 (2) |  | 7 (2) | 20 (2) |  |
Family history of breast cancer | ||||||
 Yes | 44 (26) | 75 (15) | 0.001 | 91 (22) | 165 (14) | < 0.001 |
 No | 124 (74) | 423 (85) |  | 331 (78) | 1032 (86) |  |
Ever alcohol consumption | ||||||
 Yes | 119 (71) | 318 (64) | 0.08 | 248 (59) | 759 (63) | 0.2 |
 Never | 49 (29) | 180 (36) |  | 174 (41) | 438 (37) |  |
Ever use of oral contraceptive | ||||||
 Yes | 102 (61) | 324 (65) | 0.2 | 247 (59) | 711 (59) | 0.8 |
 Never | 66 (39) | 172 (35) |  | 174 (41) | 492 (40) |  |
 Missing | 0 (0) | 2 (0) |  | 1 (0) | 4 (1) |  |
Ever use of hormonal therapy | ||||||
 Yes | 54 (32) | 141 (28) | 0.3 | 134 (32) | 333 (28) | 0.1 |
 Never | 113 (67) | 355 (71) |  | 284 (67) | 859 (72) |  |
 Missing | 1 (1) | 2 (1) |  | 4 (1) | 5 (0) |  |