Table 1. Demographics, tumor and clinical characteristics, and treatment of study population with IDC.
| Total (n = 6,180) No. (%) |
Chinese (a) (n = 4,738) No. (%) |
Malay (b) (n = 702) No. (%) |
Indian (c) (n = 335) No. (%) |
Others (d) (n = 405) No. (%) |
p-value | Pairwise comparisons | |
|---|---|---|---|---|---|---|---|
| Age at diagnosis (yr)* | 51 (19–93) | 51 (20–93) | 49 (19–85) | 52 (28–81) | 47 (22–84) | < 0.001 | ab: < 0.001, ac: 0.852 |
| ad: < 0.001, bc: < 0.001 | |||||||
| bd: 0.026, cd: < 0.001 | |||||||
| Menopause status | < 0.001 | ab: 0.003, ac: 0.990 | |||||
| Premenopause | 2,453 (43.8) | 1,789 (42.0) | 349(49.7) | 121 (38.8) | 222 (58.4) | ad: < 0.001, bc: 0.022 | |
| Postmenopause | 2,851 (50.9) | 2,244 (52.6) | 286 (44.4) | 174 (55.8) | 147 (38.7) | bd: 0.056, cd: < 0.001 | |
| Perimenopause | 295 (5.3) | 230 (5.4) | 37 (5.8) | 17 (5.5) | 11 (2.9) | ||
| Breastfed | < 0.001 | ab: < 0.001, ac: < 0.001 | |||||
| Yes | 1,348 (24.1) | 857 (20.2) | 243 (37.3) | 117 (38.2) | 131 (35.2) | ad: < 0.001, bc: 1.000 | |
| No | 4,235 (75.9) | 3,396 (79.9) | 409 (62.7) | 189 (61.8) | 241 (64.8) | bd: 0.986, cd: 0.961 | |
| Family history | 0.188† | - | |||||
| Yes | 803 (13.7) | 596 (13.3) | 96 (14.3) | 47 (14.9) | 64 (17.1) | ||
| No | 5,042 (86.3) | 3,887 (86.7) | 576 (85.7) | 268 (85.1) | 311 (82.9) | ||
| Presentation | 3,491 (77.5) | 2,620 (76.1) | 447 (84.0) | 187 (75.4) | 237 (84.3) | < 0.001 | ab: < 0.001, ac: 1.000 |
| Clinical | 1,012 (22.5) | 822 (23.9) | 85 (16.0) | 61 (24.6) | 44 (15.7) | ad: 0.010, bc: 0.024 | |
| Screening | bd: 1.000, cd: 0.059 | ||||||
| T stage | < 0.001 | ab: < 0.001, ac: 0.162 | |||||
| T1‡ | 3,010 (48.7) | 2,442 (51.5) | 262 (37.3) | 139 (41.5) | 167 (41.2) | ad: 0.016, bc: 0.924 | |
| T2 | 2,556 (41.4) | 1,870 (39.5) | 337 (48.1) | 163 (48.7) | 186 (45.9) | bd: 0.999, cd: 1.000 | |
| T3 | 549 (8.9) | 387 (8.2) | 88 (12.5) | 29 (8.7) | 45 (11.1) | ||
| T4 | 43 (0.7) | 23 (0.5) | 12 (1.7) | 3 (0.9) | 5 (1.2) | ||
| Nodal involvement | < 0.001 | ab: < 0.001, ac: 1.000 | |||||
| Yes | 686 (11.4) | 486 (10.5) | 115 (16.7) | 36 (10.9) | 49 (12.2) | ad: 0.874, bc: 0.083 | |
| No | 5,349 (88.6) | 4,131 (89.5) | 572 (83.3) | 294 (89.1) | 352 (87.8) | bd: 0.239, cd: 0.995 | |
| N stage | < 0.001 | ab: < 0.001, ac: 0.082 | |||||
| N0§ | 3,162 (51.2) | 2,528 (53.4) | 293 (41.7) | 151 (45.1) | 190 (46.9) | ad: 0.138, bc: 0.103 | |
| N1∥ | 1,551 (25.1) | 1,172 (24.7) | 172 (24.5) | 102 (30.5) | 105 (25.9) | bd: 0.610, cd: 0.994 | |
| N2 | 862 (13.9) | 626 (13.2) | 132 (18.8) | 44 (13.1) | 60 (14.8) | ||
| N3 | 605 (9.8) | 412 (8.7) | 105 (15) | 38 (11.3) | 50 (12.4) | ||
| Histologic grade | < 0.001 | ab: < 0.001, ac: 0.402 | |||||
| Grade 1 | 869 (14.8) | 699 (15.5) | 66 (10.1) | 41 (12.7) | 63 (16.6) | ad: 0.587, bc: 0.083 | |
| Grade 2 | 2,167 (37) | 1,742 (38.7) | 184 (28.1) | 114 (35.3) | 127 (33.5) | bd: 0.002, cd: 0.920 | |
| Grade 3 | 2,823 (48.2) | 2,062 (45.8) | 404 (61.8) | 168 (52) | 189 (49.9) | ||
| Histology subtype | < 0.001 | ab: 0.001, ac: 0.151 | |||||
| Endocrine+/HER2– | 4,503 (76.1) | 3,487 (77.2) | 480 (71.1) | 233 (71) | 303 (76.5) | ad: 1.000, bc: 0.320 | |
| Endocrine+/HER2+ | 554 (9.4) | 394 (8.7) | 93 (13.8) | 32 (9.8) | 35 (8.8) | bd: 0.464, cd: 0.834 | |
| Triple-negative | 700 (11.8) | 518 (11.5) | 80 (11.9) | 55 (16.8) | 47 (11.9) | ||
| Endocrine–/HER2+ | 159 (2.7) | 118 (2.6) | 22 (3.3) | 8 (2.4) | 11 (2.8) | ||
| Hormone sensitivity | 0.004 | ab: 0.010, ac: 0.182 | |||||
| Highly responsive | 3,442 (58.3) | 2,665 (59.1) | 358 (53.0) | 181 (55.4) | 238 (60.4) | ad: 0.994, bc: 0.996 | |
| Incompletely responsive | 1,053 (17.8) | 817 (18.1) | 122 (18.1) | 51 (15.6) | 63 (16) | bd: 0.310, cd: 0.810 | |
| Nonresponsive | 1,414 (23.9) | 1,031 (22.9) | 195 (28.9) | 95 (29.1) | 93 (23.6) | ab: 0.005, ac: 0.956 | |
| HER2 | 0.006 | ||||||
| Positive | 1,353 (24.4) | 1,006 (23.9) | 196 (30.7) | 65 (20.6) | 86 (22.8) | ad: 0.999, bc: 0.024 | |
| Negative | 3,783 (68.2) | 2,894 (68.6) | 396 (62.0) | 227 (72.1) | 266 (70.6) | bd: 0.098, cd: 1.000 | |
| Equivocal | 411 (7.4) | 316 (7.5) | 47 (7.4) | 23 (7.3) | 25 (6.6) |
IDC=invasive ductal carcinoma; HER2=human epidermal growth factor receptor 2.
*Median (range); †As the p-value is greater than 0.05, no pairwise comparisons were made; ‡Including T1mic; §Including N0 (i+); ∥Including N1mic.