Table 3. Distribution of variables related to the screening protocol and women's characteristics by screen-detected and interval cancer (overall and subtypes).
| SDC | IC | TI | FN | MS | OT | |
| N (%) | N (%) | N (%) | N (%) | N (%) | N (%) | |
| Total | 1,570 | 1,012 | 489 | 235 | 174 | 114 |
| Reading method | ||||||
| Double | 1,450 (92.4) | 889 (87.8)* | 424 (86.7) | 202 (86.0) | 162 (93.1) | 101 (88.6)+ |
| Single | 120 (7.6) | 123 (12.2) | 65 (13.3) | 33 (14.0) | 12 (6.9) | 13 (11.4) |
| Type of Mammogram | ||||||
| SFM | 1,470 (93.6) | 941 (93.0) | 446 (91.2) | 216 (91.9) | 168 (96.6) | 111 (97.4)+ |
| DM | 100 (6.4) | 71 (7.0) | 43 (8.8) | 19 (8.1) | 6 (3.4) | 3 (2.6) |
| Participation | ||||||
| Successive | 1,100 (70.1) | 742 (73.3) | 361 (73.8) | 176 (74.9) | 128 (73.6) | 77 (67.5) |
| Initial | 470 (29.9) | 270 (26.7) | 128 (26.2) | 59 (25.1) | 46 (26.4) | 37 (32.5) |
| Early Recall | ||||||
| No | 1,423 (90.6) | 985 (97.3)* | 474 (96.9) | 227 (96.6) | 170 (97.7) | 114 (100.0)+ |
| Yes | 147 (9.4) | 27 (2.7) | 15 (3.1) | 8(3.4) | 4 (2.3) | 0 (0.0) |
| Previous false-positive | ||||||
| No | 1,475 (93.9) | 904 (89.3)* | 444 (90.8) | 185 (78.7) | 163 (93.7) | 112 (98.2)+ |
| Yes | 95 (6.1) | 108 (10.7) | 45 (9.2) | 50 (21.3) | 11 (6.3) | 2 (1.8) |
| Age group (yrs) | ||||||
| 44–49 | 81 (5.2) | 61 (6.1)* | 32 (6.5) | 12 (5.1) | 8 (4.6) | 10 (8.8)+ |
| 50–54 | 421 (26.8) | 351 (34.7) | 170 (34.8) | 73 (31.1) | 54 (31.0) | 54 (47.4) |
| 55–59 | 438 (27.9) | 271 (26.8) | 136 (27.8) | 57 (24.3) | 55 (31.6) | 23 (20.2) |
| 60–64 | 460 (29.3) | 224 (22.1) | 103 (21.1) | 62 (26.4) | 39 (22.4) | 20 (17.5) |
| 65–70 | 170 (10.8) | 104 (10.3) | 48 (9.8) | 31 (13.2) | 18 (10.3) | 7 (6.1) |
| HRT use | ||||||
| No | 1,306 (91.5) | 771 (87.9)* | 366 (87.6) | 175 (88.8) | 139 (85.8) | 91 (91.0)+ |
| Yes | 122 (8.5) | 106 (12.1) | 52 (12.4) | 22 (11.2) | 23 (14.2) | 9 (9.0) |
| Menopausal status | ||||||
| Postmenopausal | 1,222 (85.5) | 725 (81.7)* | 346 (81.6) | 166 (83.0) | 138 (86.8) | 75 (72.1)+ |
| Premenopausal | 207 (14.5) | 162 (18.3) | 78 (18.4) | 34 (17.0) | 21 (13.2) | 29 (27.9) |
| Family history of breast cancer | ||||||
| No | 1,224 (87.5) | 760 (87.5) | 352 (85.6) | 175 (89.3) | 139 (88.5) | 94 (89.5) |
| Yes | 175 (12.5) | 109 (12.5) | 59 (14.4) | 21 (10.7) | 18 (11.5) | 11 (10.5) |
| Previous benign biopsy outside screening | ||||||
| No | 1,168 (88.1) | 717 (88.0) | 347 (89.4) | 158 (83.6) | 134 (88.1) | 78 (90.7) |
| Yes | 158 (11.9) | 98 (12,0) | 41 (10.6) | 31 (16.4) | 18 (11.8) | 8 (9.3) |
| Density | ||||||
| <25% | 607 (38.7) | 325 (32.1)* | 153 (31.3) | 86 (36.6) | 68 (39.1) | 18 (15.8)+ |
| 25–50% | 428 (27.3) | 169 (26.6) | 134 (27.4) | 64 (27.2) | 49 (28.2) | 22 (19.3) |
| 50–75% | 352 (22.4) | 252 (24.9) | 123 (25.2) | 47 (20.0) | 40 (23.0) | 42 (36.8) |
| >75% | 183 (11.7) | 166 (16.4) | 79 (16.2) | 38 (16.2) | 17 (9.8) | 32 (28.1) |
*P-value<0.05, Chi-squared test between screen-detected and interval cancer.
+P-value<0.05, Chi-squared test between screen-detected and interval cancer subtype.
Abbreviations: SDC: Screen-detected Cancer, IC: Interval Cancer, TI: True interval, FN: False-negative, MS: Minimal-signs, OT: Occult tumours, SFM: Screen-film mammography, DM: Digital mammography and HRT: Hormone Replacement Therapy.